The cingulum bundle: Anatomy, function, and dysfunction

Multi-modal risk factors differentiate suicide attempters from ideators in military veterans with major depressive disorder

BACKGROUND

The suicide rate for United States military veterans is 1.5× higher than that of non-veterans. To meaningfully advance suicide prevention efforts, research is needed to delineate factors that differentiate veterans with suicide attempt/s, particularly in high-risk groups, e.g., major depressive disorder (MDD), from those with suicidal ideation (no history of attempt/s). The current study aimed to identify clinical, neurocognitive, and neuroimaging variables that differentiate suicide-severity groups in veterans with MDD.

METHODS

Sixty-eight veterans with a DSM-5 diagnosis of MDD, including those with no ideation or suicide attempt (N = 21; MDD-SI/SA), ideation-only (N = 17; MDD + SI), and one-or-more suicide attempts (N = 30; MDD + SA; aborted, interrupted, actual attempts), participated in this study. Participants underwent a structured diagnostic interview, neurocognitive assessment, and 3 T-structural/diffusion tensor magnetic-resonance-imaging (MRI). Multinomial logistic regression models were conducted to identify variables that differentiated groups with respect to the severity of suicidal behavior.

RESULTS

Relative to veterans with MDD-SI/SA, those with MDD + SA had significantly higher left cingulum fractional anisotropy, decreased attentional control on emotional-Stroop, and faster response time with intact accuracy on Go/No-Go. Relative to MDD + SI, MDD + SA had higher left cingulum fractional anisotropy and faster response time with intact accuracy on Go/No-Go.

LIMITATIONS

Findings are based on retrospective, cross-sectional data and cannot identify causal relationships. Also, a healthy control group was not included given the study's focus on differentiating suicide profiles in MDD.

CONCLUSIONS

This study suggests that MRI and neurocognition differentiate veterans with MDD along the suicide-risk spectrum and could inform suicide-risk stratification and prevention efforts in veterans and other vulnerable populations.

Understanding structural-functional connectivity coupling in patients with major depressive disorder: A white matter perspective

PURPOSE

To elucidate the structural-functional connectivity (SC-FC) coupling in white matter (WM) tracts in patients with major depressive disorder (MDD).

METHODS

A total of 178 individuals diagnosed with MDD and 173 healthy controls (HCs) were recruited for this study. The Euclidean distance was calculated to assess SC-FC coupling. The primary analyses focused on investigating alterations in SC-FC coupling in WM tracts of individuals with MDD. Additionally, we explored the association between coupling and clinical symptoms. Secondary analyses examined differences among three subgroups of MDD: those with suicidal ideation (SI), those with a history of suicidal attempts (SA), and those non-suicidal (NS).

RESULTS

The study revealed increased SC-FC coupling mainly in the middle cerebellar peduncle and bilateral corticospinal tract (PFDR < 0.05) in patients with MDD compared with HCs. Additionally, right cerebral peduncle coupling strength exhibited a significant positive correlation with Hamilton Anxiety Scale scores (r = 0.269, PFDR = 0.041), while right cingulum (hippocampus) coupling strength showed a significant negative correlation with Nurses' Global Assessment of Suicide Risk scores (r = -0.159, PFDR = 0.036). An increase in left anterior limb of internal capsule (PBonferroni < 0.01) and left corticospinal tract (PBonferroni < 0.05) coupling has been observed in MDD with SI. Additionally, a decrease in right posterior limb of internal capsule coupling has been found in MDD with SA (PBonferroni < 0.05).

CONCLUSIONS

This study emphasizes the variations in SC-FC coupling in WM tracts in individuals with MDD and its subgroups, highlighting the crucial role of WM networks in the pathophysiology of MDD.

Higher skeletal muscle mitochondrial oxidative capacity is associated with preserved brain structure up to over a decade

Impaired muscle mitochondrial oxidative capacity is associated with future cognitive impairment, and higher levels of PET and blood biomarkers of Alzheimer's disease and neurodegeneration. Here, we examine its associations with up to over a decade-long changes in brain atrophy and microstructure. Higher in vivo skeletal muscle oxidative capacity via MR spectroscopy (post-exercise recovery rate, kPCr) is associated with less ventricular enlargement and brain aging progression, and less atrophy in specific regions, notably primary sensorimotor cortex, temporal white and gray matter, thalamus, occipital areas, cingulate cortex, and cerebellum white matter. Higher kPCr is also associated with less microstructural integrity decline in white matter around cingulate, including superior longitudinal fasciculus, corpus callosum, and cingulum. Higher in vivo muscle oxidative capacity is associated with preserved brain structure up to over a decade, particularly in areas important for cognition, motor function, and sensorimotor integration.

Advances in the fMRI analysis of the default mode network: a review

The default mode network (DMN) is a singular pattern of synchronization between brain regions, usually observed using resting-state functional magnetic resonance imaging (rs-fMRI) and functional connectivity analyses. In comparison to other brain networks that are primarily involved in attentional-demanding tasks (such as the frontoparietal network), the DMN is linked with self-referential activities, and alterations in its pattern of connectivity have been related to a wide range of disorders. Structural connectivity analyses have highlighted the vital role of the posterior cingulate cortex and the precuneus as integrative hubs, and advanced parcellation methods have further contributed to elucidate the DMN's regions, enriching its explanatory potential across cognitive functions and dysfunctions. Interestingly, the study of its temporal characteristics - the specific frequency spectrum of BOLD signal oscillations -, its developmental trajectory over the course of life, and its interaction with other networks, provides new insight into the DMN's defining features. In this context, this review aims to synthesize the state of the art in the study of the DMN to provide the most updated findings to anyone interested in its research. Finally, some weaknesses in the current state of knowledge and some interesting lines of work for further progress in the study of the DMN are presented.

Emergence of multiple spontaneous coherent subnetworks from a single configuration of human connectome coupled oscillators model

Multi-state metastability in neuroimaging signals reflects the brain's flexibility to transition between network configurations in response to changing environments or tasks. We modeled these dynamics with a Kuramoto network of 90 nodes oscillating at an intrinsic frequency of 40 Hz, interconnected using human brain structural connectivity strengths and delays. We simulated this model for 30 min to generate multi-state metastability. We identified global coupling and delay parameters that maximize spectral entropy, a proxy for multi-state metastability. At this operational point, multiple frequency-specific coherent sub-networks spontaneously emerge across oscillatory modes, persisting for periods between 140 and 4300 ms, reflecting flexible and sustained dynamic states. The topography of these sub-networks aligns with empirical resting-state neuroimaging data. Additionally, periodic components of the EEG spectra from young healthy participants correlate with maximal multi-state metastability, while dynamics away from this point correlate with sleep and anesthesia spectra. Our findings suggest that multi-state metastable functional dynamics observed in empirical data emerge from specific interactions of structural topography and connection delays, providing a platform to study mechanisms underlying flexible dynamics of cognition.

White matter lipidome alterations in the schizophrenia brain

Numerous brain imaging studies have reported white matter alterations in schizophrenia, but the lipidome analysis of the corresponding tissue remains incomplete. In this study, we investigated the lipidome composition of six subcortical white matter regions corresponding to major axonal tracks in both control subjects and schizophrenia patients. All six regions exhibited a consistent pattern of quantitative lipidome alterations in schizophrenia, involving myelin-forming and mitochondria associated lipid classes. While alteration levels of myelin-forming lipids, particularly sphingolipids, aligned with the extent of the myelin changes reported in structural brain imaging studies, a significant decrease of mitochondria in the white matter, indicated by the lipidome alterations, was not previously investigated. To verify this effect, we performed lipidome analysis in a larger set of individuals and in the mitochondria-enriched membrane fraction, as well as directly quantified mitochondrial content. Our results suggest a substantial reduction of the mitochondrial quotient accompanied by the imbalance in myelin lipids in schizophrenia white matter.

Lifetime depression, sleep disruption and brain structure in the UK Biobank cohort

Whether depression and poor sleep interact or have statistically independent associations with brain structure and its change over time is not known. Within a subset of UK Biobank participants with neuroimaging and subjective and/or objective sleep data (n = 28,351), we examined associations between lifetime depression and sleep disruption and their interaction with structural neuroimaging measures, both cross-sectionally and longitudinally. Sleep variables were: self-reported insomnia and difficulty getting up; actigraphy-derived short sleep (<7 h); sustained inactivity bouts during daytime (SIBD); and sleep efficiency. Imaging measures were white matter microstructure, subcortical volumes, and volume, cortical thickness and surface area of 24 cortical regions of interest. Individuals with lifetime depression (self-reported, mental health questionnaire or health records) were contrasted with healthy controls. Interactions between depression and difficulty getting up for i) right nucleus accumbens volume and ii) mean diffusivity of forceps minor reflected a larger negative association of poor sleep in the presence vs. absence of depression. Depression was associated with widespread reductions in white matter integrity. Depression, higher SIBD and difficulty getting up were individually associated with smaller cortical volumes and surface area, particularly in the frontal and parietal lobes. Many regions showed age-related decline, but this was not exacerbated by either depression or sleep disturbance. Overall, we identified widespread cross-sectional associations of both lifetime depression and sleep measures with brain structure. Findings were more consistent with additive rather than synergistic effects - although in some regions we observed greater magnitude of deleterious associations from poor sleep phenotypes in the presence of depression.

Decision-making using the Iowa gambling test in unaffected first-degree relatives of obsessive-compulsive disorder: Comparison with healthy controls and patients with obsessive-compulsive disorder

Decision-making has been suggested as an endophenotype candidate for obsessive-compulsive disorder (OCD). However, few studies have examined whether decision-making under ambiguity is an endophenotype of OCD. This study aimed to investigate decision-making under ambiguity, as assessed by the Iowa Gambling Task (IGT), in patients with OCD and unaffected first-degree relatives (UFDR). Forty-seven non-medicated, non-co-morbid patients with OCD, 30 UFDR, and 47 healthy controls (HC) were compared in terms of decision-making using the IGT. The correlation between obsessive-compulsive symptoms and IGT performance was also investigated. Patients with OCD and UFDR performed worse than HC on the IGT. No correlation was found between obsessive-compulsive symptoms and IGT performance. A deficit in decision-making under ambiguity may be a trait and an endophenotype candidate for OCD.

LMX1B missense-perturbation of regulatory element footprints disrupts serotonergic forebrain axon arborization

Pathogenic coding mutations are prevalent in human neuronal transcription factors (TFs) but how they disrupt development is poorly understood. Lmx1b is a master transcriptional regulator of postmitotic Pet1 neurons that give rise to mature serotonin (5-HT) neurons; over two hundred pathogenic heterozygous mutations have been discovered in human LMX1B, yet their impact on brain development has not been investigated. Here, we developed mouse models with different LMX1B DNA-binding missense mutations. Missense heterozygosity broadly altered Pet1 neuron transcriptomes, but expression changes converged on axon and synapse genes. Missense heterozygosity effected highly specific deficits in the postnatal maturation of forebrain serotonin axon arbors, primarily in the hippocampus and motor cortex, which was associated with spatial memory defects. Digital genomic footprinting (DGF) revealed that missense heterozygosity caused complete loss of Lmx1b motif protection and chromatin accessibility at sites enriched for a distal active enhancer/active promoter histone signature and homeodomain binding motifs; at other bound Lmx1b motifs, varying levels of losses, gains or no change in motif binding and accessibility were found. The spectrum of footprint changes was strongly associated with synapse and axon genes. Further, Lmx1b missense heterozygosity caused wide disruption of Lmx1b-dependent GRNs comprising diverse TFs expressed in Pet1 neurons. These findings reveal an unanticipated continuum of Lmx1b missense-forced perturbations on Pet1 neuron regulatory element TF binding and accessibility. Our work illustrates the power of DGF for gaining unique insight into how TF missense mutations interfere with developing neuronal GRNs.

Significance Statement

We modeled human LMX1B missense mutations in mice to explore how they disrupt brain serotonin neuron development. Missense heterozygosity selectively impaired postnatal formation of serotonin axon arbors throughout the forebrain, notably in the hippocampus and motor cortex. DGF revealed that Lmx1b missense heterozygosity exerted a continuum of footprint changes associated with synapse and axon gene expression. Footprint changes ranged from total eliminations to partial losses and gains within the Pet1 neuronal epigenome. LMX1B missense mutations may cause human brain pathogenesis by selectively disrupting cis regulatory elements controlling 5-HT axon arbor formation thus impairing 5-HT delivery to presynaptic release sites.

Wider and faster degeneration of white matter in Parkinson's disease with possible REM sleep behaviour disorder

BACKGROUND

In Parkinson's disease (PD), rapid eye movement (REM) sleep behaviour disorder (RBD) signifies a poorer prognosis, yet its impact on white matter (WM) degeneration remains unclear. The study examined the effect of RBD on WM alterations in PD progression.

METHODS

The study included 45 PD patients with possible RBD (PD-pRBD), 38 PD patients without possible RBD (PD-npRBD), and 79 healthy controls (HC). All patients underwent clinical assessments and diffusion MRI scans at least once a year for up to 4 visits. 79 HC underwent the same protocol at baseline. WM metrics, including fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD), were calculated using tract-based spatial statistics. Linear mixed-effects models were conducted to examine the changes in clinical features and WM fibers.

RESULTS

At baseline, PD-npRBD showed increased RD in several regions, predominantly in bilateral uncinate fasciculus (UF) and inferior longitudinal fasciculus (ILF), compared to HC (PFDR<0.05). During follow-up, PD-npRBD had further FA decrease in left UF and ILF (PFDR<0.05). PD-pRBD showed reduced FA in several regions relative to HC at baseline (PFDR<0.05), and faster FA decline in left UF and ILF than PD-npRBD during follow-up, with more extensive FA decrease in other regions such as anterior thalamic radiation and inferior fronto-occipital fasciculus (PFDR<0.05). Moreover, increased RD in the left corticospinal tract correlated with motor symptoms (p = 0.045) in PD-pRBD.

CONCLUSIONS

PD patients with pRBD demonstrated more extensive WM degeneration and accelerated degeneration in the left ILF and UF during the disease course. However, due to the lack of PSG verification, these results should be interpreted cautiously while directly relating to RBD. These findings provide new insights into the neural structural basis associated with the potential impact of RBD on PD progression.

White matter microstructure damage measured by automated fiber quantification correlates with pain symptoms in lung cancer patients

To investigative the white matter (WM) alterations in lung cancer patients with cancer pain (CP+), and explore the correlations between damaged WM fiber tracts and clinical indicators. Twenty-six CP+, 26 lung cancer patients without CP (CP-), and 31 healthy controls (HC) were recruited. All participants underwent diffusion tensor imaging (DTI) and clinical assessments. Automated fiber quantification (AFQ) technique was performed to identify the 20 WM fiber bundles, and the fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were extracted. Intergroup comparisons of these diffusion metrics were conducted based on the entire fiber bundle level and 100 node levels along each tract. The associations between altered diffusion metrics and the numeric rating scale (NRS) scores, as well as the pain duration, were analyzed. At the entire level, the CP + group showed impaired WM structure in the right cingulum hippocampus (CH_R). At the pointwise level, the CP + group exhibited extensive nodal FA reduction or MD, RD, and AD elevation. In addition, the AD of the posterior portion of the right inferior longitudinal fasciculus (ILF_R, nodes 71-75) in the CP + group was positively correlated with the pain duration, and the FA of CH_R (nodes 22-38) was negatively correlated with NRS score. Extensive WM microstructural damage may be a pattern of brain abnormalities in lung cancer patients with CP, and in particular, specific nodal disruption along pain-related fiber tracts may be a sensitive imaging biomarker to characterize the severity and duration of CP.

Transcortical resection of a giant bilobed falcine meningioma

INTRODUCTION

Falcine meningiomas present significant surgical challenges because they often involve the falx bilaterally, are concealed by a significant amount of normal brain parenchyma and are frequently deep in location and in close proximity to the anterior cerebral arteries. Many prefer the interhemispheric approach for these lesions, but this operative corridor is not without risk as venous infarctions and cortical injury can occur.

CLINICAL PRESENTATION

We present an alternative technique utilizing a transcortical approach to resect a giant, bilobed falcine meningioma in a 68-year-old female who presented with progressive abulia, urinary incontinence, and bilateral lower extremity weakness over 2 years. A unilateral right frontal craniotomy and a corticectomy through the right superior frontal gyrus was used to safely resect the entire tumor. The patient tolerated the procedure well and was discharged home without issue. Pathology demonstrated that the lesion was an atypical meningioma and she subsequently received adjuvant fractionated radiotherapy. At 2-year follow-up, she has no neurologic deficits, never developed any postoperative seizures and has not had any evidence of tumor recurrence.

CONCLUSION

The transcortical approach can be used as a safe alternative for resecting falcine meningiomas without adding significant undue risk to the patient.

White matter correlates of impulsive behavior in healthy individuals: A diffusion magnetic resonance imaging study

Aim

To explore white matter (WM) tracts linked to impulsivity using the diffusion magnetic resonance imaging (DMRI) connectometry method.

Methods

We analyzed 218 healthy participants from the Leipzig Study for Mind-Body-Emotion Interactions database. Impulsivity correlations with DMRI-derived WM changes were assessed using Urgency-Premeditation-Perseverance-Sensation (UPPS) Impulsive Behavior Scale subscales: lack of perseverance (PE), lack of premeditation (PM), sensation seeking (SS), and negative urgency. DMRI data were processed using connectometry, adjusting for sex and age, to examine WM tract integrity via quantitative anisotropy (QA). Also, two additional interaction analyses were conducted to separately examine the interaction effect between WM QA, and sex and age in predicting impulsive behavior scores. The significance level in our statistical analyses was set at a false discovery rate (FDR) below 0.05.

Results

QA in the bilateral cerebellum and middle cerebellar peduncle showed a negative association with PE and PM severity (FDR = 0.0004). QA in the middle cerebellar peduncle, corpus callosum body, and forceps major demonstrated a positive association with SS (FDR = 0.0001). Conversely, QA in forceps minor had a positive association with PM (FDR = 0.004), and QA in forceps minor and bilateral cingulum showed a positive association with SS (FDR = 0.0005). Age and sex had no significant effects on the association between WM QA and UPPS subscale scores.

Conclusion

Impulsivity is linked to distinct WM integrity changes in various tracts, including the corpus callosum, cerebellum, and cingulum, offering insights into the pathophysiology of impulsivity and guiding future research.

Segmental abnormalities of white matter microstructure in multiple sclerosis and neuromyelitis optica spectrum disorder identified by automated fiber quantification

BACKGROUND

Multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD) are different in pathogenesis, but both could lead to white matter (WM) microstructural damage. The aim of this study was to explore the differences in the patterns of WM fiber tract damage in relapsing-remitting MS (RRMS) and NMOSD by automated fiber quantification (AFQ).

MATERIALS AND METHODS

Forty-one RRMS patients, 30 NMOSD patients and 30 healthy controls (HC) underwent MRI examination. AFQ was applied to identify and quantify 100 equally spaced nodes of specific WM fiber tracts for each participant. Measurements of fractional anisotropy (FA), mean diffusion (MD), axial diffusivity (AD) and radial diffusivity (RD) for each segment of a specific fiber tract were compared between RRMS, NMOSD and HC.

RESULTS

The decrease in FA was found in 7 fiber tracts in entire tract comparison and 9 fiber tracts in pointwise comparison in RRMS patients. However, the FA in left thalamic radiation (TR) and right uncinate fasciculus showed significant differences between RRMS and HC only in the pointwise comparison, but not in the entire tract comparison. The MD, AD and RD of WM fiber tracts in RRMS patients were extensively increased both in the entire level and in the pointwise level. NMOSD patients showed significant FA decrease in left TR and callosum forceps minor (CF_minor), and significant RD increase in CF_minor in the pointwise level. In the pointwise comparison between RRMS and NMOSD, significant FA decrease was found in right inferior fronto-occipital fasciculus and bilateral inferior longitudinal fasciculus in RRMS patients, focal or widespread MD, AD and RD increase was found in multiple fiber tracts.

CONCLUSION

The AFQ approach is a more sensitive way to reflect WM microstructural abnormalities, revealing extensive WM microstructural damage in RRMS and limited WM fiber tract damage in NMOSD.

Neurite Orientation Dispersion and Density Imaging (NODDI) reveals white matter microstructural changes in Obstructive Sleep Apnea Hypopnea Syndrome (OSAHS) patients with cognitive impairment

PURPOSE

This study aimed to assess changes in white matter microstructure among patients undergoing obstructive sleep apnea hypopnea syndrome (OSAHS) complicated by cognitive impairment through neurite orientation dispersion and density imaging (NODDI), and evaluate the relationship to cognitive impairment as well as the diagnostic performance in early intervention.

METHODS

Totally 23 OSAHS patients, 43 OSAHS patients complicated by cognitive impairment, and 15 healthy controls were enrolled in OSA, OSACI and HC groups of this work. NODDI toolbox and FMRIB's Software Library (FSL) were used to calculate neurite density index (NDI), Fractional anisotropy (FA), volume fraction of isotropic water molecules (Viso), and orientation dispersion index (ODI). Tract-based spatial statistics (TBSS) were carried out to examine the above metrics with one-way ANOVA. This study explored the correlations of the above metrics with mini-mental state examination (MMSE), and montreal cognitive assessment (MoCA) scores. Furthermore, receiver operating characteristic (ROC) curves were plotted. Meanwhile, area under curve (AUC) values were calculated to evaluate the diagnostic performance of the above metrics.

RESULTS

NDI, ODI, Viso, and FA were significantly different among different brain white matter regions, among which, difference in NDI showed the greatest statistical significance. In comparison with HC group, OSA group had reduced NDI and ODI, whereas elevated Viso levels. Conversely, compared to the OSA group, the OSACI group displayed a slight increase in NDI and ODI values, which remained lower than HC group, viso values continued to rise. Post-hoc analysis highlighted significant differences in these metrics, except for FA, which showed no notable changes or correlations with neuropsychological tests. ROC analysis confirmed the diagnostic efficacy of NDI, ODI, and Viso with AUCs of 0.6908, 0.6626, and 0.6363, respectively, whereas FA's AUC of 0.5042, indicating insufficient diagnostic efficacy.

CONCLUSIONS

This study confirmed that NODDI effectively reveals microstructural changes in white matter of OSAHS patients with cognitive impairment, providing neuroimaging evidence for early clinical diagnosis and intervention.

Evaluation of White Matter Integrity by Using Diffusion Tensor Imaging in Patients with Presbycusis

RATIONALE AND OBJECTIVES

This study aims to evaluate white matter microstructure integrity in patients diagnosed with presbycusis (age-related hearing loss) using diffusion tensor imaging (DTI) and to investigate the relationship between DTI parameters and hearing loss severity.

MATERIALS AND METHODS

Patients aged 50 and above with presbycusis (pure-tone average [PTA] ≥20dB) were categorized as mild (PTA 20-34dB), moderate (PTA 35-49dB), or severe (PTA ≥50dB). Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were measured in 16 white matter regions. The relationship between DTI parameters and speech discrimination scores was assessed using multiple linear regression, adjusting for age, sex, and vascular risk profile.

RESULTS

The study included 148 patients (mild=32, moderate=84, severe=32). DTI analysis showed significantly lower FA in the left cingulum (p = 0.001) and right IFOF (p = 0.003) in the severe group compared to the mild and moderate groups, while RD in the left cingulum was higher in the severe group (p = 0.006). The mild group exhibited significantly lower left IFOF RD (p < 0.001) compared to the moderate and severe groups, and significantly lower left cingulum body MD (p = 0.004) compared to the severe group. Significant associations were found between speech discrimination scores and DTI parameters, including right hippocampal cingulum MD (p = 0.030), left IFOF RD (p = 0.033), right Heschl's gyrus MD (p = 0.018), and AD (p = 0.008).

CONCLUSION

This study demonstrated significant alterations in white matter microstructure across different severities of presbycusis. Further research is needed to fully understand the cognitive and central auditory dysfunctions associated with presbycusis.

Social Buffering of PTSD: Longitudinal Effects and Neural Mediators

BACKGROUND

Post-traumatic stress disorder (PTSD) is a well characterized psychiatric disorder featuring changes in mood and arousal following traumatic events. Prior animal and human studies on social support in the peri-traumatic window demonstrate a buffering effect with regards to acute biological and psychological stress symptoms. Fewer studies have explored the magnitude and mechanism on how early, post-trauma social support can reduce longitudinal PTSD severity.

METHODS

In this study we investigated the beneficial impact of social support on longitudinal PTSD symptoms, and probed brain regions sensitive to this buffering phenomenon, such as the amygdala and ventromedial prefrontal cortex. In the multi-site AURORA study, n=315 participants reported PTSD symptoms (PCL-5) and perceived emotional support (PROMIS) at 2-weeks, 8-weeks, 3-months, and 6-months post-ED visit. Additionally, neuroimaging data was collected at 2 weeks post trauma.

RESULTS

We hypothesized that early, post-trauma social support would be linked with greater fractional anisotropic (FA) values in white matter tracts that have known connectivity between the amygdala and prefrontal cortex and would predict reduced neural reactivity to social threat cues in the amygdala. Interestingly, while we observed greater FA in the bilateral cingulum and bilateral uncinate fasciculus as a function of early post-trauma emotional support, we also identified greater threat reactivity in the precuneus/posterior cingulate, a component of the default mode network.

CONCLUSION

Our findings suggest that the neurocircuitry underlying the response to social threat cues are facilitated through broader pathways that involve the posterior hub of the default mode network.

The Impact of Insufficient Sleep on White Matter Development in Late Childhood and Early Adolescence

PURPOSE

Sleep is vital for brain development. Animal models have suggested that insufficient sleep affects axons and dendrites (known as neurites). However, the effects of insufficient sleep on neurites during brain development in humans remain understudied. Deriving neurite density index and orientation dispersion index (ODI) in a large sample (N = 1,016; 47.44% girls), we aimed to identify the effects of insufficient sleep on white matter development between late childhood (mean age [standard deviation] = 9.96 [0.62] years) and early adolescence (mean age [standard deviation] = 11.94 [0.64] years).

METHODS

Longitudinal Latent Class Analysis was used to derive longitudinal classes based on sleep duration from the Sleep Disturbance Scale for Children. The Child Behavior Checklist characterized behavioral (internalizing: anxious/depressed, withdrawn/depressed, somatic; externalizing: social, thought, attention, rule-breaking, and aggressive) problems. Regression analyses evaluated the effects of sleep classes on neurite density index, ODI, and standard tensor-based metrics (Fractional Anisotropy) changes over time, the focal or widespread effects along the tracts, and whether these effects were associated with behavioral problems.

RESULTS

Insufficient (<9 hours; N = 569) and sufficient sleep (>9 hours; N = 447) groups were identified. Insufficient sleep was associated with worsening fiber coherence (greater ODI) in most tracts, including cingulum bundle (F(1,982) = 9.22, p = .002, Q = 0.009), forceps minor (F(1,982) = 5.30, p = .021, Q = 0.026), and superior longitudinal fasciculus (F(1,982) = 7.41, p = .007, Q = 0.015). These effects were focal, particularly in the frontal portions of the tracts. No other metric was affected (p > .050). In addition, greater ODI in the cingulum bundle was associated with more anxious/depressed problems (β = 0.10, p = .012, Q = 0.036).

DISCUSSION

Our findings suggest that insufficient sleep during this sensitive period affects white matter development, which in turn affects internalizing problems. Our findings support the importance of promoting sufficient sleep during early adolescence.

Breakthroughs and challenges for generating brain network-based biomarkers of treatment response in depression

Treatment outcomes widely vary for individuals diagnosed with major depressive disorder, implicating a need for deeper understanding of the biological mechanisms conferring a greater likelihood of response to a particular treatment. Our improved understanding of intrinsic brain networks underlying depression psychopathology via magnetic resonance imaging and other neuroimaging modalities has helped reveal novel and potentially clinically meaningful biological markers of response. And while we have made considerable progress in identifying such biomarkers over the last decade, particularly with larger, multisite trials, there are significant methodological and practical obstacles that need to be overcome to translate these markers into the clinic. The aim of this review is to review current literature on brain network structural and functional biomarkers of treatment response or selection in depression, with a specific focus on recent large, multisite trials reporting predictive accuracy of candidate biomarkers. Regarding pharmaco- and psychotherapy, we discuss candidate biomarkers, reporting that while we have identified candidate biomarkers of response to a single intervention, we need more trials that distinguish biomarkers between first-line treatments. Further, we discuss the ways prognostic neuroimaging may help to improve treatment outcomes to neuromodulation-based therapies, such as transcranial magnetic stimulation and deep brain stimulation. Lastly, we highlight obstacles and technical developments that may help to address the knowledge gaps in this area of research. Ultimately, integrating neuroimaging-derived biomarkers into clinical practice holds promise for enhancing treatment outcomes and advancing precision psychiatry strategies for depression management. By elucidating the neural predictors of treatment response and selection, we can move towards more individualized and effective depression interventions, ultimately improving patient outcomes and quality of life.

Temporopolar blurring signifies abnormalities of white matter in mesial temporal lobe epilepsy

OBJECTIVE

The single-center retrospective cohort study investigated underlying pathogenic mechanisms and clinical significance of patients with temporal lobe epilepsy and hippocampal sclerosis (TLE-HS), in the presence/absence of gray-white matter abnormalities (usually called "blurring"; GMB) in ipsilateral temporopolar region (TPR) on MRI.

METHODS

The study involved 105 patients with unilateral TLE-HS (60 GMB+ and 45 GMB-) who underwent standard anterior temporal lobectomy, along with 61 healthy controls. Resected specimens were examined under light microscope. With combined T1-weighted and DTI data, we quantitatively compared large-scale morphometric features and exacted diffusion parameters of ipsilateral TPR-related superficial and deep white matter (WM) by atlas-based segmentation. Along-tract analysis was added to detect heterogeneous microstructural alterations at various points along deep WM tracts, which were categorized into inferior longitudinal fasciculus (ILF), uncinate fasciculus (UF), and temporal cingulum.

RESULTS

Comparable seizure semiology and postoperative seizure outcome were found, while the GMB+ group had significantly higher rate of HS Type 1 and history of febrile seizures, contrasting with significantly lower proportion of interictal contralateral epileptiform discharges, HS Type 2, and increased wasteosomes in hippocampal specimens. Similar morphometric features but greater WM atrophy with more diffusion abnormalities of superficial WM was observed adjacent to ipsilateral TPR in the GMB+ group. Moreover, microstructural alterations resulting from temporopolar GMB were more localized in temporal cingulum while evenly and widely distributed along ILF and UF.

INTERPRETATION

Temporopolar GMB could signify more severe and widespread microstructural damage of white matter rather than a focal cortical lesion in TLE-HS, affecting selection of surgical procedures.

Development of white matter in young adulthood: The speed of brain aging and its relationship with changes in fractional anisotropy

White matter (WM) development has been studied extensively, but most studies used cross-sectional data, and to the best of our knowledge, none of them considered the possible effects of biological (vs. chronological) age. Therefore, we conducted a longitudinal multimodal study of WM development and studied changes in fractional anisotropy (FA) in the different WM tracts and their relationship with cortical thickness-based measures of brain aging in young adulthood. A total of 105 participants from the European Longitudinal Study of Pregnancy and Childhood (ELSPAC) prenatal birth cohort underwent magnetic resonance imaging (MRI) at the age of 23-24, and the age of 28-30 years. At both time points, FA in the different WM tracts was extracted using the JHU atlas, and brain age gap estimate (BrainAGE) was calculated using the Neuroanatomical Age Prediction using R (NAPR) model based on cortical thickness maps. Changes in FA and the speed of cortical brain aging were calculated as the difference between the respective variables in the late vs. early 20s. We demonstrated tract-specific increases as well as decreases in FA, which indicate that the WM microstructure continues to develop in the third decade of life. Moreover, the significant interaction between the speed of cortical brain aging, tract, and sex on mean FA revealed that a greater speed of cortical brain aging in young adulthood predicted greater decreases in FA in the bilateral cingulum and left superior longitudinal fasciculus in young adult men. Overall, these changes in FA in the WM tracts in young adulthood point out the protracted development of WM microstructure, particularly in men.

Association between prenatal maternal sleep quality, neonatal uncinate fasciculus white matter, and infant negative emotionality

BACKGROUND

Poor prenatal maternal sleep is a pervasive, yet modifiable, health concern affecting maternal and foetal wellbeing. Experimental rodent studies demonstrate that prenatal maternal sleep deprivation affects offspring brain development and leads to adverse outcomes, including increased anxiety-like behaviour. We examined the relation between prenatal maternal sleep quality and neonatal white matter development and subsequent infant negative emotionality.

METHODS

Participants included 116 mother-infant (53% female) dyads. Prenatal sleep quality was prospectively assessed three times during gestation (16, 29, and 35 gestational weeks) using the Pittsburgh Sleep Quality Index. Neonatal white matter, as indexed by fractional anisotropy (FA), was assessed via diffusion weighted magnetic resonance imaging. Negative emotionality was measured via behavioural observation and maternal report when the infant was 6-months of age.

FINDINGS

More prenatal sleep problems across pregnancy were associated with higher neonatal FA in the uncinate fasciculus (left: b = 0.20, p = .004; right: b = 0.15, p = .027). Higher neonatal uncinate FA was linked to infant negative emotionality, and uncinate FA partially mediated the association between prenatal maternal sleep and behavioural observation of infant negative emotionality.

INTERPRETATION

Findings highlight prenatal sleep as an environmental signal that affects the developing neonatal brain and later infant negative emotionality.

FUNDING

National Institutes of Health (R01MH109662, R01HL155744, P50HD103573, K12AR084226, F32 Training fellowships MH125572, HL165844, MH106440, and diversity supplement R01HL155744-01S1).

Brain structural associations of syntactic complexity and diversity across schizophrenia spectrum and major depressive disorders, and healthy controls

Deviations in syntax production have been well documented in schizophrenia spectrum disorders (SSD). Recently, we have shown evidence for transdiagnostic subtypes of syntactic complexity and diversity. However, there is a lack of studies exploring brain structural correlates of syntax across diagnoses. We assessed syntactic complexity and diversity of oral language production using four Thematic Apperception Test pictures in a sample of N = 87 subjects (n = 24 major depressive disorder (MDD), n = 30 SSD patients both diagnosed according to DSM-IV-TR, and n = 33 healthy controls (HC)). General linear models were used to investigate the association of syntax with gray matter volume (GMV), fractional anisotropy (FA), axial (AD), radial (RD), and mean diffusivity (MD). Age, sex, total intracranial volume, group, interaction of group and syntax were covariates of no interest. Syntactic diversity was positively correlated with the GMV of the right medial pre- and postcentral gyri and with the FA of the left superior-longitudinal fasciculus (temporal part). Conversely, the AD of the left cingulum bundle and the forceps minor were negatively correlated with syntactic diversity. The AD of the right inferior-longitudinal fasciculus was positively correlated with syntactic complexity. Negative associations were observed between syntactic complexity and the FA of the left cingulum bundle, the right superior-longitudinal fasciculus, and the AD of the forceps minor and the left uncinate fasciculus. Our study showed brain structural correlates of syntactic complexity and diversity across diagnoses and HC. This contributes to a comprehensive understanding of the interplay between linguistic and neural substrates in syntax production in psychiatric disorders and HC.

Structural and functional alterations in different types of delusions across schizophrenia spectrum: A systematic review

BACKGROUND

Despite the high clinical role of delusions as a transnosological psychopathological phenomenon, the number of experimental studies on the different types of delusions across schizophrenia spectrum is still relatively small, and their results are somehow inconsistent. We aimed to understand the current state of knowledge regarding the structural and functional brain alterations in delusions to determine whether particular types of delusions are associated with specific brain changes and to identify common alterations underlying the formation and persistence of delusions regardless of their content.

METHODS

For this systematic review, we followed PRISMA guidelines to search in PubMed for English papers published between 1953 and September 30, 2023. The initial inclusion criteria for screening purposes were articles that investigated delusions or subclinical delusional beliefs in schizophrenia spectrum disorders, high clinical or genetic risk for schizophrenia using fMRI, sMRI or/and dwMRI methods. Exclusion criteria during the screening phase were articles that investigated lesion-induced or substance-induced delusions, delusions in Alzheimer's disease and other neurocognitive disorders, single case studies and non-human studies. The publication metadata were uploaded to the web-tool for working on systematic reviews, Rayyan. For each of the studies, a table was filled out with detailed information.

RESULTS

We found 1752 records, of which 95 full-text documents were reviewed and included in the current paper. Both nonspecific and particular types of delusions were associated with widespread structural and functional alterations. The most prominent areas affected across all types of delusions were the superior temporal cortex (predominantly left language processing areas), anterior cingulate/medial prefrontal cortex and insula. The most reproducible findings in paranoia may be alterations in the functioning of the amygdala and its interactions with other regions. Somatic delusions and delusional infestation were mostly characterized by alterations in the insula and thalamus.

DISCUSSION

The data are ambiguous; however, in general the predictive processing framework seems to be the most widely accepted approach to explaining different types of delusions. Aberrant prediction errors signaling during processing of social, self-generated and sensory information may lead to inaccuracies in assessing the intentions of others, self-relevancy of ambiguous stimuli, misattribution of self-generated actions and unusual sensations, which could provoke delusional ideation with persecutory, reference, control and somatic content correspondingly. However, currently available data are still insufficient to draw conclusions about the specific biological mechanisms of predictive coding account of delusions. Thus, further studies exploring more homogeneous groups and interaction of diagnoses by types of delusions are needed. There are also some limitations in this review. Studies that investigate delusions induced by lesions, substance abuse or neurodegeneration and studies using modalities other than fMRI, sMRI or dwMRI were not included in the review. Due to the relatively small number of publications, we systematized them based on a certain type of delusions, while the results could also be affected by the diagnosis of patients, the presence and type of therapy, illness duration etc.

The brain topological alterations in the structural connectome and correlations with clinical characteristics in type 1 narcolepsy

OBJECTIVE

To explore topological alterations of white matter (WM) structural connectome, and their associations with clinical characteristics in type 1 narcolepsy (NT1).

METHODS

46 NT1 patients and 34 age- and sex-matched healthy controls were recruited for clinical data and diffusion tensor imaging collection. Using graph theory analysis, the topology metrics of structural connectome, rich club organization, and connectivity properties were compared between two groups. Furthermore, partial correlation analysis was performed between the network characteristics of 90 nodes or weakened edges and clinical data using Pearson or Spearman correlation, controlling by age and sex.

RESULTS

Between-group comparison reflected that NT1 patients exhibited sleep disorders with comorbidities of impaired cognition and psychological problems. In patients, the global efficiency, local efficiency, and average clustering coefficient were significantly lower, whereas characteristic path length was larger compared to healthy control. Pertinently, nodal path length of left middle frontal gyrus was positively correlated with Pittsburgh Sleep Quality Index scores. The rich club analysis identified six affected nodes: bilateral dorsolateral superior frontal gyrus, bilateral supplementary motor area, left hippocampus, and left pallidum. Furthermore, six significantly weakened structural connections seeding from these rich club nodes have shown significant correlations with clinical index or polysomnography parameters.

CONCLUSION

In NT1 patients, WM structural connectome has shown to be disrupted, which were primarily distributed in frontal-parietal cortex, subcortical regions, and particularly cingulate, potentially affecting their clinical manifestations.

White matter integrity upon progesterone antagonism in individuals with premenstrual dysphoric disorder: A randomized placebo-controlled diffusion tensor imaging study

BACKGROUND

Premenstrual dysphoric disorder (PMDD) is a depressive disorder triggered by fluctuations of progesterone and estradiol during the luteal phase of the menstrual cycle. Selective progesterone receptor modulation (SPRM), while exerting an antagonistic effect on progesterone and maintaining estradiol on moderate levels, has shown beneficial effects on the mental symptoms of PMDD. Progesterone is also known for its neuroprotective effects, while synthetic progestins have been suggested to promote myelination. However, the impact of SPRM treatment on white matter microstructure is unexplored.

METHODS

Diffusion tensor imaging was employed to collect data on white matter integrity in patients with PMDD, before and after treatment with ulipristal acetate (an SPRM) or placebo, as part of a double-blind randomized controlled-trial. Tract based spatial statistics were performed to investigate SPRM treatment vs. placebo longitudinal effects on fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD), on the whole white matter skeleton.

RESULTS

Voxel-wise analyses indicated no change over time in any white matter microstructure metrics in individuals treated with SPRM versus placebo. Improvement in PMDD symptoms did not correlate with changes in white matter microstructure. In secondary, exploratory, cross-sectional comparisons during treatment, the SPRM group displayed lower FA and higher MD, RD, and AD than the placebo group in several tracts.

CONCLUSION

The main findings suggest that SPRM treatment did not impact white matter microstructure compared with placebo. However, secondary exploratory analyses yielded between-group differences after treatment, which call for further investigation on the tracts potentially impacted by progesterone antagonism.

CLINICAL TRIAL REGISTRATION

EUDRA-CT 2016-001719-19; "Selective progesterone receptor modulators for treatment of premenstrual dysphoric disorder. A randomized, double-blind, placebo-controlled study."; https://www.clinicaltrialsregister.eu/ctr-search/trial/2016-001719-19/SE.

Long-term cognitive training enhances fluid cognition and brain connectivity in individuals with MCI

Amnestic mild cognitive impairment (aMCI) is a risk factor for Alzheimer's disease (AD). Multi-domain cognitive training (CT) may slow cognitive decline and delay AD onset. However, most work involves short interventions, targeting single cognitive domains or lacking active controls. We conducted a single-blind randomized controlled trial to investigate the effect of a 6-month, multi-domain CT on Fluid Cognition, functional connectivity in memory and executive functioning networks (primary outcomes), and white matter microstructural properties (secondary outcome) in aMCI. Sixty participants were randomly assigned to either a multi-domain CT or crossword training (CW) group, and thirty-four participants completed the intervention. We found a significant group-by-time interaction in Fluid Cognition (p = 0.007, F (1,28) = 8.26, Cohen's d = 0.38, 95% confidence interval [CI]: 2.45-14.4), with 90% of CT patients showing post-intervention improvements (p < 0.01, Cohen's d = 0.7). The CT group also showed better post-intervention Fluid Cognition than healthy controls (HCs, N = 45, p = 0.045). Functional connectivity analyses showed a significant group-by-time interaction (Cohen's d ≥ 0.8) in the dorsolateral prefrontal cortex (DLPFC) and inferior parietal cortex (IPC) networks. Specifically, CT displayed post-intervention increases whereas CW displayed decreases in functional connectivity. Moreover, increased connectivity strength between the left DLPFC and medial PFC was associated with improved Fluid Cognition. At a microstructural level, we observed a decline in fiber density (FD) for both groups, but the CT group declined less steeply (1.3 vs. 2%). The slower decline in FD for the CT group in several tracts, including the cingulum-hippocampus tract, was associated with better working memory. Finally, we identified regions in cognitive control and memory networks for which baseline functional connectivity and microstructural properties were associated with changes in Fluid Cognition. Long-term, multi-domain CT improves cognitive functioning and functional connectivity and delays structural brain decline in aMCI (ClinicalTrials.gov number: NCT03883308).

The cingulum: a central hotspot for the battle against chronic intractable pain?

Chronic pain causes a major burden on patient's lives, in part due to its profound socioeconomic impact. Despite the development of various pharmacological approaches and (minor) invasive treatments, a subset of patients remain refractory, hence why alternative targeted neurosurgical interventions like cingulotomy and deep brain stimulation of the anterior cingulate cortex should be considered in the last resort. Despite clinical evidence supporting the potential of these treatments in the management of chronic intractable pain, physicians remain reluctant on its clinical implementation. This can be partially attributed to the lack of clear overviews summarizing existent data. Hence, this article aims to evaluate the current status of cingulotomy and deep brain stimulation of the anterior cingulate cortex in the treatment of chronic intractable pain, to provide insight in whether these neurosurgical approaches and its target should be reconsidered in the current era. In the current study, a literature searches was performed using the PubMed database. Additional articles were searched manually through reviews or references cited within the articles. After exclusion, 24 and 5 articles remained included in the analysis of cingulotomy and deep brain stimulation of the anterior cingulate cortex, respectively. Results indicate that various surgical techniques have been described for cingulotomy and deep brain stimulation of the anterior cingulate cortex. Cingulotomy is shown to be effective 51-53% and 43-64% of patients with neoplastic and non-neoplastic pain at ≤6 months follow-up, and 82% (9/11) and 76% (90/118) at ≥ 12months follow-up, respectively. With regard to deep brain stimulation of the anterior cingulate cortex, no data on neoplastic pain was reported, however, 59% (10/17) and 57% (8/14) of patients with non-neoplastic pain were considered responders at ≤ 6 months and ≥ 12months follow-up, respectively. The most reported adverse events include change in affect (>6.9%, >29/420) and confusion (>4.8%, >20/420) for cingulotomy, and infection (12.8%, 6/47), seizures (8.5%, 4/47) and decline in semantic fluency (6.4%, 3/47) for deep brain stimulation of the anterior cingulate cortex. It can be concluded that cingulotomy and deep brain stimulation of the anterior cingulate cortex are effective last resort strategies for patients with refractory non-neoplastic and neoplastic pain, especially in case of an affective emotional component. Future research should be performed on the cingulum as a neurosurgical target as it allows for further exploration of promising treatment options for chronic intractable pain.

Gray matter and cognitive alteration related to chronic obstructive pulmonary disease patients: combining ALE meta-analysis and MACM analysis

Chronic obstructive pulmonary disease (COPD) is frequently comorbid with cognitive impairment, but it has not been paid enough attention, and its neuroanatomical characteristics have not been fully identified. Voxel-based morphometric (VBM) studies comparing gray matter (GM) abnormalities in COPD patients with healthy controls (HCs) were searched using 8 electronic databases from the inception to March 2023. Stereotactic data were extracted and tested for convergence and differences using the activation likelihood estimation (ALE) method. Moreover, based on the ALE results, a structural meta-analytic connectivity modeling (MACM) was conducted to explore the co-atrophy pattern in patients with COPD. Last, behavioral analysis was performed to assess the functional roles of the regions affected by COPD. In total, 11 studies on COPD with 949 participants were included. Voxel-based meta-analysis revealed significant GM abnormalities in the right postcentral gyrus (including inferior parietal lobule), left precentral gyrus, and left cingulate gyrus (including paracentral lobule) in patients with COPD compared with HCs. Further MACM analysis revealed a deeper co-atrophy pattern between the brain regions with abnormal GM structure and the insula in COPD patients. Behavioral analysis showed that the abnormal GM structure in the left cingulate gyrus (including paracentral lobule) was strongly associated with cognitive function, especially executive function. COPD comorbid with cognitive impairment has a specific neurostructural basis of GM structural abnormalities, which may also involve a deeper co-atrophy pattern between the insula. These findings enhance our understanding of the underlying neuropathogenesis and suggest potential imaging markers for cognitive impairment in COPD patients. PROSPERO registration number: CRD42022298722.

Role of diffusion tensor imaging in the evaluation of white matter integrity in idiopathic intracranial hypertension

OBJECTIVES

To determine whether idiopathic intracranial hypertension (IIH) may affect white matter integrity and optic pathways by using diffusion tensor imaging (DTI) and to correlate the DTI metrics with intracranial pressure (ICP).

METHODS

This study is a retrospective case-control study. A total of 42 patients who underwent lumbar puncture and those with elevated ICP, meeting the diagnostic criteria for IIH, were included in the study. All patients had supportive magnetic resonance imaging findings for the diagnosis of IIH. The headache control group comprised 36 patients who presented to the Neurology Department with infrequent episodic tension-type headache, had a normal neurologic examination, and had clinical and radiological findings suggestive of normal ICP. For each patient with IIH, clinical findings and ophthalmological measurements were recorded. The apparent diffusion coefficient (ADC), fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD) values were calculated using a region of interest-based method in different white matter tracts and optic pathways and compared.

RESULTS

A total of 42 patients diagnosed with IIH (three males, 39 females), with a mean (standard deviation [SD] age of 38.1 (8.9) years), and 36 headache controls (10 males, 26 females, mean [SD] age; 38.1 [9.4] years) were included in the study. The mean (SD) body mass index (BMI) of the patients with IIH was 25.2 (1.9) kg/m2, and the mean (SD) BMI of the headache controls was 23.3 (1.5) kg/m2 (p < 0.001). Decreased FA values and increased RD values in the cingulum were detected in patients with IIH compared to the headache controls (p = 0.003, Cohen's d = 0.681; p = 0.002 Cohen's d = -0.710). Decreased AD values in the left and right superior cerebellar peduncle and increased ADC values in the middle cerebellar peduncle were detected in patients with IIH compared to the headache controls (p < 0.001, Cohen's d = 0.961; p = 0.009, Cohen's d = 0.607; p = 0.015, Cohen's d = -0.564). Increased ADC and RD values and decreased FA values in optic nerve were detected in patients with IIH (p = 0.010, Cohen's d = -0.603; p = 0.004, Cohen's d = -0.676; p = 0.015 Cohen's d = 0.568). A positive correlation was found between the cerebrospinal fluid pressure and ADC values of the left and right superior and left inferior longitudinal fasciculus, genu of the corpus callosum, and right optic radiation (r = 0.43, p = 0.005; r = 0.31, p = 0.044; r = 0.39, p = 0.010; r = 0.35, p = 0.024; r = 0,41, p = 0.007). There was a positive correlation between the retinal nerve fiber layer thickness and the ADC values of the optic nerve (r = 0.32, p = 0.039).

CONCLUSIONS

Intracranial hypertension can be associated with deteriorated DTI values, which might be interpreted as a sign of impaired white matter microstructural integrity in many brain regions beyond the periventricular white matter. Pressure-induced edema and axonal degeneration may be the potential underlying mechanisms of this microstructural damage.

Cross-sectional and longitudinal evaluation of white matter microstructure damage and cognitive correlations by automated fibre quantification in relapsing-remitting multiple sclerosis patients

The purpose of this study was to characterize whole-brain white matter (WM) fibre tracts by automated fibre quantification (AFQ), capture subtle changes cross-sectionally and longitudinally in relapsing-remitting multiple sclerosis (RRMS) patients and explore correlations between these changes and cognitive performance A total of 114 RRMS patients and 71 healthy controls (HCs) were enrolled and follow-up investigations were conducted on 46 RRMS patients. Fractional anisotropy (FA), mean diffusion (MD), axial diffusivity (AD), and radial diffusivity (RD) at each node along the 20 WM fibre tracts identified by AFQ were investigated cross-sectionally and longitudinally in entire and pointwise manners. Partial correlation analyses were performed between the abnormal metrics and cognitive performance. At baseline, compared with HCs, patients with RRMS showed a widespread decrease in FA and increases in MD, AD, and RD among tracts. In the pointwise comparisons, more detailed abnormalities were localized to specific positions. At follow-up, although there was no significant difference in the entire WM fibre tract, there was a reduction in FA in the posterior portion of the right superior longitudinal fasciculus (R_SLF) and elevations in MD and AD in the anterior and posterior portions of the right arcuate fasciculus (R_AF) in the pointwise analysis. Furthermore, the altered metrics were widely correlated with cognitive performance in RRMS patients. RRMS patients exhibited widespread WM microstructure alterations at baseline and alterations in certain regions at follow-up, and the altered metrics were widely correlated with cognitive performance in RRMS patients, which will enhance our understanding of WM microstructure damage and its cognitive correlation in RRMS patients.

Altered associations between white matter structure and psychopathology in previously institutionalized adolescents

Previously institutionalized adolescents show increased risk for psychopathology, though placement into high-quality foster care can partially mitigate this risk. White matter (WM) structure is associated with early institutional rearing and psychopathology in youth. Here we investigate associations between WM structure and psychopathology in previously institutionalized youth. Adolescent psychopathology data were collected using the MacArthur Health and Behavior Questionnaire. Participants underwent diffusion MRI, and data were processed using fixel-based analyses. General linear models investigated interactions between institutionalization groups and psychopathology on fixel metrics. Supplementary analyses also examined the main effects of psychopathology and institutionalization group on fixel metrics. Ever-Institutionalized children included 41 randomized to foster care (Mage=16.6), and 40 to care-as-usual (Mage=16.7)). In addition, 33 participants without a history of institutionalization were included as a reference group (Mage=16.9). Ever-Institutionalized adolescents displayed altered general psychopathology-fixel associations within the cerebellar peduncles, inferior longitudinal fasciculi, corticospinal tract, and corpus callosum, and altered externalizing-fixel associations within the cingulum and fornix. Our findings indicate brain-behavior associations reported in the literature may not be generalizable to all populations. Previously institutionalized youth may develop differential brain development, which in turn leads to altered neural correlates of psychopathology that are still apparent in adolescence.

Cerebral white matter injury in haemodialysis patients: a cross-sectional tract-based spatial statistics and fixel-based analysis

Background

End-stage renal disease (ESRD) patients on maintenance haemodialysis (HD) often have damage to brain white matter (WM) and cognitive impairment. However, whether this damage is caused by maintenance HD or renal dysfunction is unclear. Herein we investigate the natural progression of WM damage in patients with ESRD and the effects of HD on WM using tract-based spatial statistics (TBSS) and fixel-based analysis (FBA).

Methods

Eighty-one ESRD patients, including 41 with no dialysis (ND) and 40 on HD, and 46 healthy controls (HCs) were enrolled in this study. The differences in WM among the three groups [ESRD patients with HD (ESRD-HD), ESRD patients without HD (ESRD-ND) and HCs] were analysed using TBSS and FBA. Pairwise comparison was then used to compare the differences in WM between two groups. The relationships between WM and neurocognitive assessments/clinical data were analysed in ESRD patients with and without HD.

Results

The damage to WM in ESRD-ND and ESRD-HD appeared around the lateral ventricles in TBSS, while FBA reflected that the changes had extended to adjacent WM in the anterior hemisphere, with a larger region in ESRD-HD compared with ESRD-ND and the brainstem was also widely affected in ESRD-HD. The Montreal Cognitive Assessment (MoCA) scores were lower in the ESRD-HD group. RD in the body of the corpus callosum were negatively correlated with MoCA scores in both groups. Fiber density and cross-section (FDC) in the left thalamo-prefrontal projection (T_PREFL) and left and right cingulum (CGL and CGR) were positively correlated with MoCA scores in both groups. Creatinine (Cr) was positively correlated with FDC in some frontal projection fibres in the striatum and thalamus, CG and fronto-pontine tract and was positively correlated with FD mainly in premotor projection fibres in the striatum and thalamus in the ESRD-HD group. Cr was negatively correlated with mean and radial diffusivity in regions of the corona radiata in the ESRD-ND group.

Conclusions

FBA is more sensitive in detecting differences between ESRD patients and HCs. When ESRD patients receive maintenance HD, the degree of WM damage may not be aggravated, but the range of damaged WM may be expanded, especially in the anterior hemisphere and brainstem. Some of these changes in the anterior hemisphere may contribute to cognitive decline.

Brain white matter microstructural alterations in Behcet's syndrome correlate with cognitive impairment and disease severity: A diffusion tensor imaging study

OBJECTIVES

To evaluate the microstructural integrity of brain white matter tracts in patients with Neuro-Behcet's syndrome (NBS) and Behcet's syndrome (BS) without neurological manifestations using diffusion tensor imaging (DTI) and to investigate potential utility of DTI as a surrogate biomarker of neurocognitive functioning and disease severity.

METHODS

This cross-sectional study comprised 34 NBS patients and 32 BS patients without neurological involvement, identified based on the International Study Group of the Behcet's disease (ISGBD) and the International Consensus Recommendation (ICR) criteria, as well as 33 healthy controls. Cognitive functions, including attention, memory, language, abstraction, executive control, visuospatial skills, and sensorimotor performance were assessed using standardized questionnaires. DTI data were analyzed using tract-based spatial statistics (TBSS) and automated probabilistic tractography to investigate inter-group differences. Subsequently, correlations between tensor-derived parameters of white matter tracts, neurocognitive test scores, and disease severity measures were examined.

RESULTS

DTI revealed decreased fractional anisotropy and increased radial diffusivity, mean diffusivity, and axial diffusivity in both supratentorial and infratentorial white matter in NBS patients, indicating widespread loss of microstructural integrity. Moreover, this loss of integrity was also observed in BS patients without neurological manifestations, albeit to a lesser extent. In NBS patients, certain white matter tracts, including cingulum bundle, were associated with poor cognitive performance across multiple domains and disease severity.

DISCUSSION

DTI findings might potentially serve as a neuroimaging marker to predict the extent of neurocognitive impairment and disease severity associated with central nervous system involvement in BS.

How fiber bundle alterations differ in presumed LATE and amnestic Alzheimer's disease

INTRODUCTION

Typical Alzheimer's disease (AD) and limbic-predominant age-related TAR DNA-binding protein 43 (TDP-43) encephalopathy (LATE) are two neurodegenerative diseases that present with a similar initial amnestic clinical phenotype but are associated with distinct proteinopathies.

METHODS

We investigated white matter (WM) fiber bundle alterations, using fixel-based analysis, a state-of-the-art diffusion magnetic resonance imaging model, in early AD, presumed LATE, and controls. We also investigated regional cortical atrophy.

RESULTS

Both amnestic AD and presumed LATE patients exhibited WM alterations in tracts of the temporal and limbic lobes and in callosal fibers connecting superior frontal gyri. In addition, presumed LATE patients showed alterations in callosal fibers connecting the middle frontal gyri and in the cerebello-thalamo-cortical tract. Cortical thickness was reduced in regions connected by the most altered tracts.

DISCUSSION

These findings, the first to describe WM fiber bundle alterations in presumed LATE, are consistent with results on cortical atrophy and with the staging system of tau or TDP-43 accumulation.

HIGHLIGHTS

Fixel-based analysis revealed white matter (WM) fiber bundle alterations in presumed limbic-predominant age-related TAR DNA-binding protein 43 encephalopathy (LATE) patients identified by isolated episodic/limbic amnesia, the absence of positive Alzheimer's disease (AD) biomarkers, and no other neurological diagnosis after 2 years of follow-up. Presumed LATE and amnestic AD shared similar patterns of WM alterations in fiber bundles of the limbic and temporal lobes, in congruence with their similar limbic cognitive phenotype. Presumed LATE differed from AD by the alteration of the callosal fibers connecting the middle frontal gyri and of the cerebello-thalamo-cortical tract. WM fiber bundle alterations were consistent with results on regional cortical atrophy. The different anatomical patterns of WM degeneration could provide information on the propagation pathways of distinct proteinopathies.

Exploration of the white matter bundles connected to the pineal gland: A DTI study

PURPOSE

Pineal gland (PG) is a structure located in the midline of the brain, and is considered as a main part of the epithalamus. There are reports on the role of this area for brain function by hormone secretion, as well as few reports on its role in brain cognition. However, little knowledge is available on the PG, and in particular on the structural connectivity of this region with the other brain structures.

METHODS

Using diffusion-weighted images collected by a 3T MRI scanner, and using a sample of 61 (29 F) mentally and physically healthy young individuals in the age range of 20-30 years old, we tried to extract the white matter bundles connected to the PG. Based on prior knowledge, seven target bundles were suggested to be between the PG body and the PG roots, Pons, Periventricular region, thalamus, caudate, lentiform, suprachiasmatic nuclei, and the supercervical ganglia.

RESULTS

Nearly all the target bundles were successfully extracted, with the exception of the lentiform. Rate of identification of the tracts was different, with the bundle between the PG body and roots having the highest identification rate (97%); then it was with the Pons (70%), Periventricular region (57%), SCN (55%), left thalamus (52%), right thalamus (47%), left caudate (27%) and right caudate (22%).

CONCLUSION

This study is an attempt to expand our knowledge on the neuroanatomy of the PG, which might help for identifying further roles for it in brain functionality, and also be a help for the treatment of some disorders in the future.

Free water-corrected fractional anisotropy of the fornix and parahippocampal cingulum predicts longitudinal memory change in cognitively healthy older adults

Prior studies have reported inconsistent results regarding the relationships between the integrity of the fornix and parahippocampal cingulum and both memory performance and longitudinal change in performance. In the present study, we examined associations in a sample of cognitively healthy older adults between free water-corrected fractional anisotropy (FA) metrics derived from the fornix and cingulum, baseline memory performance, and 3-year memory change. Neither fornix nor cingulum FA correlated with memory performance at baseline. By contrast, FA of each tract was predictive of memory change, such that greater FA was associated with less longitudinal decline. These associations remained significant after controlling for FA of other white matter tracts and for performance in other cognitive domains. Furthermore, fornix and cingulum FA explained unique variance in memory change. These results suggest that free water-corrected measures of fornix and parahippocampal cingulum integrity are reliable predictors of future memory change in cognitively healthy older adults. The findings for the fornix in particular highlight the utility of correcting for free water when estimating diffusion tensor imaging metrics of white matter integrity.

Neural correlates of treatment response to ketamine for treatment-resistant depression: A systematic review of MRI-based studies

Treatment-resistant depression (TRD) is defined as patients diagnosed with depression having a history of failure with different antidepressants with an adequate dosage and treatment duration. The NMDA receptor antagonist ketamine rapidly reduces depressive symptoms in TRD. We examined neural correlates of treatment response to ketamine in TRD through a systematic review of brain magnetic resonance imaging (MRI) studies. A comprehensive search in PubMed was performed using "ketamine AND depression AND magnetic resonance." The time span for the database queries was "Start date: 2018/01/01; End date: 2024/05/31." Total 41 original articles comprising 1,396 TRD and 587 healthy controls (HC) were included. Diagnosis of depression was made using the Structured Clinical Interview for DSM Disorders (SCID), the Mini-International Neuropsychiatric Interview (MINI), and/or the clinical assessment by psychiatrists. Patients with affective psychotic disorders were excluded. Most studies applied ketamine [0.5mg/kg racemic ketamine and/or 0.25mg/kg S-ketamine] diluted in 60cc of normal saline via intravenous infusion over 40 min one time, four times, or six times spaced 2-3 days apart over 2 weeks. Clinical outcome was defined as either remission, response, and/or percentage changes of depressive symptoms. Brain MRI of the T2*-weighted imaging (resting-state or task performance), arterial spin labeling, diffusion weighted imaging, and T1-weighted imaging were acquired at baseline and mainly 1-3days after the ketamine administration. Only the study results replicated by ≥ 2 studies and were included in the default-mode, salience, fronto-parietal, subcortical, and limbic networks were regarded as meaningful. Putative brain-based markers of treatment response to ketamine in TRD were found in the structural/functional features of limbic (subgenual ACC, hippocampus, cingulum bundle-hippocampal portion; anhedonia/suicidal ideation), salience (dorsal ACC, insula, cingulum bundle-cingulate gyrus portion; thought rumination/suicidal ideation), fronto-parietal (dorsolateral prefrontal cortex, superior longitudinal fasciculus; anhedonia/suicidal ideation), default-mode (posterior cingulate cortex; thought rumination), and subcortical (striatum; anhedonia/thought rumination) networks. Brain features of limbic, salience, and fronto-parietal networks could be useful in predicting the TRD with better response to ketamine in relief of anhedonia, thought rumination, and suicidal ideation.

Structure-function coupling in macroscale human brain networks

Precisely how the anatomical structure of the brain gives rise to a repertoire of complex functions remains incompletely understood. A promising manifestation of this mapping from structure to function is the dependency of the functional activity of a brain region on the underlying white matter architecture. Here, we review the literature examining the macroscale coupling between structural and functional connectivity, and we establish how this structure-function coupling (SFC) can provide more information about the underlying workings of the brain than either feature alone. We begin by defining SFC and describing the computational methods used to quantify it. We then review empirical studies that examine the heterogeneous expression of SFC across different brain regions, among individuals, in the context of the cognitive task being performed, and over time, as well as its role in fostering flexible cognition. Last, we investigate how the coupling between structure and function is affected in neurological and psychiatric conditions, and we report how aberrant SFC is associated with disease duration and disease-specific cognitive impairment. By elucidating how the dynamic relationship between the structure and function of the brain is altered in the presence of neurological and psychiatric conditions, we aim to not only further our understanding of their aetiology but also establish SFC as a new and sensitive marker of disease symptomatology and cognitive performance. Overall, this Review collates the current knowledge regarding the regional interdependency between the macroscale structure and function of the human brain in both neurotypical and neuroatypical individuals.

Darts fast-learning reduces theta power but is not affected by Hf-tRNS: A behavioral and electrophysiological investigation

Sports trainers have recently shown increasing interest in innovative methods, including transcranial electric stimulation, to enhance motor performance and boost the acquisition of new skills during training. However, studies on the effectiveness of these tools on fast visuomotor learning and brain activity are still limited. In this randomized single-blind, sham-controlled, between-subjects study, we investigated whether a single training session, either coupled or not with 2 mA online high-frequency transcranial random noise stimulation (hf-tRNS) over the bilateral primary motor cortex (M1), would affect dart-throwing performance (i.e., radial error, arm range of motion, and movement variability) in 37 healthy volunteers. In addition, potential neurophysiological correlates were monitored before and after the training through a 32-electrode portable electroencephalogram (EEG). Results revealed that a single training session improved radial error and arm range of motion during the dart-throwing task, but not movement variability. Furthermore, after the training, resting state-EEG data showed a decrease in theta power. Radial error, arm movement, and EEG were not further modulated by hf-tRNS. This indicates that a single training session, regardless of hf-tRNS administration, improves dart-throwing precision and movement accuracy. However, it does not improve movement variability, which might require multiple training sessions (expertise resulting in slow learning). Theta power decrease could describe a more efficient use of cognitive resources (i.e., attention and visuomotor skills) due to the fast dart-throwing learning. Further research could explore different sports by applying longer stimulation protocols and evaluating other EEG variables to enhance our understanding of the lasting impacts of multi-session hf-tRNS on the sensorimotor cortex within the framework of slow learning and training assistance.

Shared and Distinct White Matter Alterations in Major Depression and Bipolar Disorder: A Systematic Review and Meta-Analysis

BACKGROUND

Identifying white matter (WM) microstructural similarities and differences between major depressive disorder (MDD) and bipolar disorder (BD) is an important way to understand the potential neuropathological mechanism in emotional disorders. Numerous diffusion tensor imaging (DTI) studies over recent decades have confirmed the presence of WM anomalies in these two affective disorders, but the results were inconsistent. This study aimed to determine the statistical consistency of DTI findings for BD and MDD by using the coordinate-based meta-analysis (CBMA) approach.

METHODS

We performed a systematic search of tract-based spatial statistics (TBSS) studies comparing MDD or BD with healthy controls (HC) as of June 30, 2024. The seed-based d-mapping (SDM) was applied to investigate fractional anisotropy (FA) changes. Meta-regression was then used to analyze the potential correlations between demographics and neuroimaging alterations.

RESULTS

Regional FA reductions in the body of the corpus callosum (CC) were identified in both of these two diseases. Besides, MDD patients also exhibited decreased FA in the genu and splenium of the CC, as well as the left anterior thalamic projections (ATP), while BD patients showed FA reduction in the left median network, and cingulum in addition to the CC.

CONCLUSIONS

The results highlighted that altered integrity in the body of CC served as the shared basis of MDD and BD, and distinct microstructural WM abnormalities also existed, which might induce the various clinical manifestations of these two affective disorders. The study was registered on PROSPERO (http://www.crd.york.ac.uk/PROSPERO), registration number: CRD42022301929.

Neuroplasticity of the white matter tracts underlying recovery of diarrhea-predominant irritable bowel syndrome following acupuncture treatment

Irritable bowel syndrome (IBS) is a functional bowel disorder frequently associated with other pain syndromes and psychiatric conditions, including depression and anxiety. These abnormalities coincide with alterations in the brain's structure, particularly in the thalamus and cingulate system. Acupuncture has been demonstrated to be highly effective in treating IBS. However, it remains unclear how white matter (WM) tracts change after acupuncture treatment, and whether the neuroplasticity of these tracts can serve as a neural marker to assist in the development of novel treatments. In this study, we aim to answer these questions by investigating longitudinal changes in the WM of the thalamus and cingulate system in a group of diarrhea-predominant irritable bowel syndrome (IBS-D) patients before and after acupuncture treatment. We found that after acupuncture treatment, as IBS symptoms improved, there were significant changes in the microstructure of the right thalamus radiation (TR) (p < 0.05) and the right cingulum hippocampus (CH) (p < 0.05). At the same time, patients with reduced IBS symptom severity scores (SSSs) were associated with the change of the right CH (p = 0.015, r = -0.491), while reduced depressive conditions correlated with the change of the left TR (p = 0.019, r = 0.418). In addition, the consequences for the quality of life (QOL) showed a correlation with the right cingulum [cingulate cortex (CC)] (p = 0.012, r = 0.504) and left TR (p = 0.027, r = -0.397). Our study highlighted the potential implications of neuroplasticity in WM tracts for IBS. Furthermore, these findings suggested that the right CH, TR, and right CC can serve as potential "biomarkers" of IBS-D recovery under acupuncture treatments.

Prefrontal-Limbic Circuitry Is Associated With Reward Sensitivity in Nonhuman Primates

BACKGROUND

Abnormal reward sensitivity is a risk factor for psychiatric disorders, including eating disorders such as overeating and binge-eating disorder, but the brain structural mechanisms that underlie it are not completely understood. Here, we sought to investigate the relationship between multimodal whole-brain structural features and reward sensitivity in nonhuman primates.

METHODS

Reward sensitivity was evaluated through behavioral economic analysis in which monkeys (adult rhesus macaques; 7 female, 5 male) responded for sweetened condensed milk (10%, 30%, 56%), Gatorade, or water using an operant procedure in which the response requirement increased incrementally across sessions (i.e., fixed ratio 1, 3, 10). Animals were divided into high (n = 6) or low (n = 6) reward sensitivity groups based on essential value for 30% milk. Multimodal magnetic resonance imaging was used to measure gray matter volume and white matter microstructure. Brain structural features were compared between groups, and their correlations with reward sensitivity for various stimuli was investigated.

RESULTS

Animals in the high sensitivity group had greater dorsolateral prefrontal cortex, centromedial amygdaloid complex, and middle cingulate cortex volumes than animals in the low sensitivity group. Furthermore, compared with monkeys in the low sensitivity group, high sensitivity monkeys had lower fractional anisotropy in the left dorsal cingulate bundle connecting the centromedial amygdaloid complex and middle cingulate cortex to the dorsolateral prefrontal cortex, and in the left superior longitudinal fasciculus 1 connecting the middle cingulate cortex to the dorsolateral prefrontal cortex.

CONCLUSIONS

These results suggest that neuroanatomical variation in prefrontal-limbic circuitry is associated with reward sensitivity. These brain structural features may serve as predictive biomarkers for vulnerability to food-based and other reward-related disorders.

Pretreatment Brain White Matter Integrity Associated With Neuropathic Pain Relief and Changes in Temporal Summation of Pain Following Ketamine

Neuropathic pain (NP) is a prevalent condition often associated with heightened pain responsiveness suggestive of central sensitization. Neuroimaging biomarkers of treatment outcomes may help develop personalized treatment strategies, but white matter (WM) properties have been underexplored for this purpose. Here we assessed whether WM pathways of the default mode network (DMN: medial prefrontal cortex [mPFC], posterior cingulate cortex, and precuneus) and descending pain modulation system (periaqueductal gray [PAG]) are associated with ketamine analgesia and attenuated temporal summation of pain (TSP, reflecting central sensitization) in NP. We used a fixel-based analysis of diffusion-weighted imaging data to evaluate WM microstructure (fiber density [FD]) and macrostructure (fiber bundle cross-section) within the DMN and mPFC-PAG pathways in 70 individuals who underwent magnetic resonance imaging and TSP testing; 35 with NP who underwent ketamine treatment and 35 age- and sex-matched pain-free individuals. Individuals with NP were assessed before and 1 month after treatment; those with ≥30% pain relief were considered responders (n = 18), or otherwise as nonresponders (n = 17). We found that WM structure within the DMN and mPFC-PAG pathways did not differentiate responders from nonresponders. However, pretreatment FD in the anterior limb of the internal capsule correlated with pain relief (r=.48). Moreover, pretreatment FD in the DMN (left mPFC-precuneus/posterior cingulate cortex; r=.52) and mPFC-PAG (r=.42) negatively correlated with changes in TSP. This suggests that WM microstructure in the DMN and mPFC-PAG pathway is associated with the degree to which ketamine reduces central sensitization. Thus, fixel metrics of WM structure may hold promise to predict ketamine NP treatment outcomes. PERSPECTIVE: We used advanced fixel-based analyses of MRI diffusion-weighted imaging data to identify pretreatment WM microstructure associated with ketamine outcomes, including analgesia and markers of attenuated central sensitization. Exploring associations between brain structure and treatment outcomes could contribute to a personalized approach to treatment for individuals with NP.

Glymphatic function assessment with diffusion tensor imaging along the perivascular space in patients with major depressive disorder and its relation to cerebral white-matter alteration

Background

The link between glymphatic system function in the brain and alterations in white-matter microstructure among individuals with major depressive disorder (MDD) remains unclear. This study aimed to examine the assessment of glymphatic system function in patients with MDD using the diffusion tensor imaging along the perivascular space (DTI-ALPS) index and to evaluate its association with cerebral-white-matter abnormalities and neuropsychological scores.

Methods

From February 2023 to November 2023, this cross-sectional study recruited 35 patients with MDD from the Psychosomatic Diseases Department of the First Affiliated Hospital of Dalian Medical University. In this time period, 23 healthy controls (HCs) were enlisted from the community and matched with the MDD cohort in terms of years of education, gender, and age. All participants underwent magnetic resonance imaging, depression, anxiety, and cognitive assessments. The tract-based spatial statistics (TBSS) analyzed DTI parameters and identified significant clusters. Automated fiber quantification (AFQ) was used to automatically identify fiber bundles with statistical differences. Mann-Whitney tests or two-sample t-tests were used for comparisons. Interobserver consistency of the DTI-ALPS measurements was evaluated using the interclass correlation coefficient (ICC). Partial correlation analyses and linear regression analyses were used to examine relationships. A comparison of the DTI-ALPS index was made between the two groups. Correlations among diffusion characteristics, neuropsychological scores, and the DTI-ALPS index were analyzed.

Results

Compared to HCs, patients with MDD exhibited a lower DTI-ALPS score (P=0.001). According to using linear regression analysis, the ALPS index was found to be an independent predictor of the Hamilton Depression Rating Scale [B=-25.32; P=0.001; 95% confidence interval (CI): -40.35 to -11.55], Hamilton Anxiety Rating Scale (B=-33.48; P=0.003; 95% CI: -55.38 to -11.24), and Montreal Cognitive Assessment total score (B=8.59; P=0.008; 95% CI: 2.38 to 14.79). According to the TBSS analysis, there were clusters of increased axial diffusivity (AD), mean diffusivity (MD), and radial diffusivity (RD) in patients with MDD as compared to HCs (all P values <0.05). A lower DTI-ALPS score was correlated with higher AD (r=-0.592; P<0.001), MD (cluster 1: r=-0.567, P=0.001; cluster 2: r=-0.581, P<0.001), and RD (r=-0.491; P=0.004) values. AFQ analysis identified the significantly different diffusion indicators in the left cingulum bundle (CB_L), left inferior longitudinal fasciculus (ILF_L), and left uncinate fasciculus (UF_L) between the two groups (all false discovery rate P values <0.05). DTI-ALPS score was negatively correlated with the AD value of CB_L (r=-0.304; P=0.024), ILF_L (r=-0.35; P=0.008), and UF_L (r=-0.354; P=0.008) in AFQ tract-level analysis. In point-wise analysis, the MD value of CB_L at nodes 33 to 36 was negatively correlated with DTI-ALPS score (r ranging from -0.504 to -0.535; P<0.01).

Conclusions

Our results indicated a decrease in DTI-ALPS index score in patients with MDD. DTI-ALPS score was associated with depression, anxiety, declined cognitive ability, and white-matter microstructural abnormalities and may thus be a promising biomarker for the partial evaluation of glymphatic system function in patients with MDD.

Impact of Sleeve Gastrectomy on Brain Structural Integrity

INTRODUCTION

Potential brain structural differences in people with obesity (PwO) who achieve over or less than 50% excess weight loss (EWL) after sleeve gastrectomy (SG) are currently unknown. We compared measures of gray matter volume (GMV) and white matter (WM) microstructural integrity of PwO who achieved over or less than 50% EWL after SG with a group of controls with obesity (CwO) without a past history of metabolic bariatric surgery.

METHODS

Sixty-two PwO underwent 1.5 T MRI scanning: 24 who achieved more than 50% of EWL after SG ("group a"), 18 who achieved less than 50% EWL after SG ("group b"), and 20 CwO ("group c"). Voxel-based morphometry and tract-based spatial Statistics analyses were performed to investigate GMV and WM differences among groups. Multiple regression analyses were performed to investigate relationships between structural and psychological measures.

RESULTS

Group a demonstrated significantly lower GMV loss and higher WM microstructural integrity with respect to group b and c in some cortical regions and several WM tracts. Positive correlations were observed in group a between WM integrity and several psychological measures; the lower the WM integrity, the higher the mental distress, emotional dysregulation, and binge eating behavior.

CONCLUSION

The present results gain a new understanding of the neural mechanisms of outcome in patients who undergo SG. We found limited GMV changes and extensive WM microstructural differences between PwO who achieved over or less than 50% EWL after SG, which may be due to higher vulnerability of WM to the metabolic dysfunction present in PwO.

Intra- and Inter-Network connectivity of the default mode network differentiates Treatment-Resistant depression from Treatment-Sensitive depression

Understanding why some patients with depression remain resistant to antidepressant medication could be elucidated by investigating their associated neural features. Although research has consistently demonstrated abnormalities in the anterior cingulate cortex (ACC) - a region that is part of the default mode network (DMN) - in treatment-resistant depression (TRD), a considerable research gap exists in discerning how these neural networks distinguish TRD from treatment-sensitive depression (TSD). We aimed to evaluate the resting-state functional connectivity (rsFC) of the ACC with other regions of the DMN to better understand the role of this structure in the pathophysiology of TRD. 35 TRD patients, 35 TSD patients, and 38 healthy controls (HC) underwent a resting-state functional MRI protocol. Seed-based functional connectivity analyses were performed, comparing the three groups for the connectivity between two subregions of the ACC (the subgenual ACC (sgACC) and the rostral ACC (rACC)) and the DMN (p < 0.05 FWE corrected). Furthermore, inter-network connectivity of the DMN with other neural networks was explored by independent component (ICA) analyses (p < 0.01, FDR corrected). The results demonstrated hyperconnectivity between the rACC and the posterior cingulate cortex in TRD relative to TSD and HC (F(2,105) = 5.335, p < 0.05). ICA found DMN connectivity to regions of the visual network (TRDTSD), differentiating the two clinical groups. These results provide confirmatory evidence of DMN hyperconnectivity and preliminary evidence for its interactions with other neural networks as key neural mechanisms underlying treatment non-responsiveness.

Advanced neuroimaging of the trigeminal nerve and the whole brain in trigeminal neuralgia: a systematic review

ABSTRACT

For trigeminal neuralgia (TN), a major role of imaging is to identify the causes, but recent studies demonstrated structural and microstructural changes in the affected nerve. Moreover, an increasing number of studies have reported central nervous system involvement in TN. In this systematic review, recent quantitative magnetic resonance imaging (MRI) studies of the trigeminal nerve and the brain in patients with TN were compiled, organized, and discussed, particularly emphasizing the possible background mechanisms and the interpretation of the results. A systematic search of quantitative MRI studies of the trigeminal nerve and the brain in patients with TN was conducted using PubMed. We included the studies of the primary TN published during 2013 to 2023, conducted for the assessment of the structural and microstructural analysis of the trigeminal nerve, and the structural, diffusion, and functional MRI analysis of the brain. Quantitative MRI studies of the affected trigeminal nerves and the trigeminal pathway demonstrated structural/microstructural alterations and treatment-related changes, which differentiated responders from nonresponders. Quantitative analysis of the brain revealed changes in the brain areas associated with pain processing/modulation and emotional networks. Studies of the affected nerve demonstrated evidence of demyelination and axonal damage, compatible with pathological findings, and have shown its potential value as a tool to assess treatment outcomes. Quantitative MRI has also revealed the possibility of dynamic microstructural, structural, and functional neuronal plasticity of the brain. Further studies are needed to understand these complex mechanisms of neuronal plasticity and to achieve a consensus on the clinical use of quantitative MRI in TN.

The relationship between blast-related mild traumatic brain injury and executive function is moderated by white matter integrity

Blast-related mild traumatic brain injury (BR mTBI) is a critical research area in recent combat veterans due to increased prevalence of survived blasts. Post-BR mTBI outcomes are highly heterogeneous and defining neurological differences may help in discrimination and prediction of cognitive outcomes. This study investigates whether white matter integrity, measured with diffusion tensor imaging (DTI), could influence how remote BR mTBI history is associated with executive control. The sample included 151 Veterans from the Minneapolis Veterans Affairs Medical Center who were administered a clinical/TBI assessment, neuropsychological battery, and DTI scan as part of a larger battery. From previous research, six white matter tracts were identified as having a putative relationship with blast severity: the cingulum, hippocampal cingulum, corticospinal tract, inferior fronto-occipital fasciculus, superior longitudinal fasciculus and uncinate. Fractional anisotropy (FA) of the a priori selected white matter tracts and report of BR mTBI were used as predictors of Trail-Making Test B (TMT-B) performance in a multiple linear regression model. Statistical analysis revealed that FA of the hippocampal cingulum moderated the association between report of at least one BR mTBI and poorer TMT-B performance (p < 0.008), such that lower FA value was associated with worse TMT-B outcomes in individuals with BR mTBI. No significant moderation existed for other selected tracts, and the effect was not observed with predictors aside from history of BR mTBI. Investigation at the individual-tract level may lead to a deeper understanding of neurological differences between blast-related and non-blast related injuries.

Decomposed FDG PET-based phenotypic heterogeneity predicting clinical prognosis and decision-making in temporal lobe epilepsy patients

OBJECTIVE

This study utilized a data-driven Bayesian model to automatically identify distinct latent disease factors represented by overlapping glucose metabolism patterns from 18F-Fluorodeoxyglucose PET (18F-FDG PET) to analyze heterogeneity among patients with TLE.

METHODS

We employed unsupervised machine learning to estimate latent disease factors from 18F-FDG PET scans, representing whole-brain glucose metabolism patterns in seventy patients with TLE. We estimated the extent to which multiple distinct factors were expressed within each participant and analyzed their relevance to epilepsy burden, including seizure onset, duration, and frequency. Additionally, we established a predictive model for clinical prognosis and decision-making.

RESULTS

We identified three latent disease factors: hypometabolism in the unilateral temporal lobe and hippocampus (factor 1), hypometabolism in bilateral prefrontal lobes (factor 2), and hypometabolism in bilateral temporal lobes (factor 3), variably co-expressed within each patient. Factor 3 demonstrated the strongest negative correlation with the age of onset and duration (r =  - 0.33, - 0.38 respectively, P < 0.05). The supervised classifier, trained on latent disease factors for predicting patient-specific antiepileptic drug (AED) responses, achieved an area under the curve (AUC) of 0.655. For post-surgical seizure outcomes, the AUC was 0.857, and for clinical decision-making, it was 0.965.

CONCLUSIONS

Decomposing 18F-FDG PET-based phenotypic heterogeneity facilitates individual-level predictions relevant to disease monitoring and personalized therapeutic strategies.