Structural covariance, topological organization, and volumetric features of amygdala subnuclei in posttraumatic stress disorder

The amygdala is divided into functional subnuclei which have been challenging to investigate due to functional magnetic resonance imaging (MRI) limitations in mapping small neural structures. Hence their role in the neurobiology of posttraumatic stress disorder (PTSD) remains poorly understood. Examination of covariance of structural MRI measures could be an alternate approach to circumvent this issue. T1-weighted anatomical scans from a 3 T scanner from non-trauma-exposed controls (NEC; n = 71, 75 % female) and PTSD participants (n = 67, 69 % female) were parcellated into 105 brain regions. Pearson's r partial correlations were computed for three and nine bilateral amygdala subnuclei and every other brain region, corrected for age, sex, and total brain volume. Pairwise correlation comparisons were performed to examine subnuclei covariance profiles between-groups. Graph theory was employed to investigate subnuclei network topology. Volumetric measures were compared to investigate structural changes. We found differences between amygdala subnuclei in covariance with the hippocampus for both groups, and additionally with temporal brain regions for the PTSD group. Network topology demonstrated the importance of the right basal nucleus in facilitating network communication only in PTSD. There were no between-group differences for any of the three structural metrics. These findings are in line with previous work that has failed to find structural differences for amygdala subnuclei between PTSD and controls. However, differences between amygdala subnuclei covariance profiles observed in our study highlight the need to investigate amygdala subnuclei functional connectivity in PTSD using higher field strength fMRI for better spatial resolution.

Functional Magnetic Resonance Imaging of the Amygdala and Subregions at 3 Tesla: A Scoping Review

The amygdalae are a pair of small brain structures, each of which is composed of three main subregions and whose function is implicated in neuropsychiatric conditions. Functional Magnetic Resonance Imaging (fMRI) has been utilized extensively in investigation of amygdala activation and functional connectivity (FC) with most clinical research sites now utilizing 3 Tesla (3T) MR systems. However, accurate imaging and analysis remains challenging not just due to the small size of the amygdala, but also its location deep in the temporal lobe. Selection of imaging parameters can significantly impact data quality with implications for the accuracy of study results and validity of conclusions. Wide variation exists in acquisition protocols with spatial resolution of some protocols suboptimal for accurate assessment of the amygdala as a whole, and for measuring activation and FC of the three main subregions, each of which contains multiple nuclei with specialized roles. The primary objective of this scoping review is to provide a broad overview of 3T fMRI protocols in use to image the activation and FC of the amygdala with particular reference to spatial resolution. The secondary objective is to provide context for a discussion culminating in recommendations for a standardized protocol for imaging activation of the amygdala and its subregions. As the advantages of big data and protocol harmonization in imaging become more apparent so, too, do the disadvantages of data heterogeneity. EVIDENCE LEVEL: 3 TECHNICAL EFFICACY: Stage 2.

Functional Connectivity Mechanisms Underlying Symptom Reduction Following Lisdexamfetamine Treatment in Binge-Eating Disorder: A Clinical Trial

Background

Speculation exists as to whether lisdexamfetamine dimesylate (LDX) acts on the functional connectivity (FC) of brain networks that modulate appetite, reward, or inhibitory control in binge-eating disorder (BED). Better insights into its action may help guide the development of more targeted therapeutics and identify who will benefit most from this medication. Here, we use a comprehensive data-driven approach to investigate the brain FC changes that underlie the therapeutic action of LDX in patients with BED.

Methods

Forty-six participants with moderate to severe BED received LDX titrated to 50 or 70 mg for an 8-week period. Twenty age-matched healthy control participants were also recruited. Resting-state functional magnetic resonance imaging was used to probe changes in brain FC pre- and post treatment and correlated with change in clinical measures.

Results

Ninety-seven percent of trial completers (n = 31) experienced remission or a reduction to mild BED during the 8-week LDX trial. Widespread neural FC changes occurred, with changes in default mode to limbic, executive control to subcortical, and default mode to executive control networks associated with improvements in clinical outcomes. These connections were not distinct from control participants at pretreatment but were different from control participants following LDX treatment. Pretreatment connectivity did not predict treatment response.

Conclusions

FC between networks associated with self-referential processing, executive function, and reward seem to underlie the therapeutic effect of LDX in BED. This suggests that LDX activates change via multiple systems, with most changes in compensatory networks rather than in those characterizing the BED diagnosis.

Neuroimaging-based classification of PTSD using data-driven computational approaches: A multisite big data study from the ENIGMA-PGC PTSD consortium

BACKGROUND

Recent advances in data-driven computational approaches have been helpful in devising tools to objectively diagnose psychiatric disorders. However, current machine learning studies limited to small homogeneous samples, different methodologies, and different imaging collection protocols, limit the ability to directly compare and generalize their results. Here we aimed to classify individuals with PTSD versus controls and assess the generalizability using a large heterogeneous brain datasets from the ENIGMA-PGC PTSD Working group.

METHODS

We analyzed brain MRI data from 3,477 structural-MRI; 2,495 resting state-fMRI; and 1,952 diffusion-MRI. First, we identified the brain features that best distinguish individuals with PTSD from controls using traditional machine learning methods. Second, we assessed the utility of the denoising variational autoencoder (DVAE) and evaluated its classification performance. Third, we assessed the generalizability and reproducibility of both models using leave-one-site-out cross-validation procedure for each modality.

RESULTS

We found lower performance in classifying PTSD vs. controls with data from over 20 sites (60 % test AUC for s-MRI, 59 % for rs-fMRI and 56 % for d-MRI), as compared to other studies run on single-site data. The performance increased when classifying PTSD from HC without trauma history in each modality (75 % AUC). The classification performance remained intact when applying the DVAE framework, which reduced the number of features. Finally, we found that the DVAE framework achieved better generalization to unseen datasets compared with the traditional machine learning frameworks, albeit performance was slightly above chance.

CONCLUSION

These results have the potential to provide a baseline classification performance for PTSD when using large scale neuroimaging datasets. Our findings show that the control group used can heavily affect classification performance. The DVAE framework provided better generalizability for the multi-site data. This may be more significant in clinical practice since the neuroimaging-based diagnostic DVAE classification models are much less site-specific, rendering them more generalizable.

Functional connectivity of amygdala subnuclei in PTSD: a narrative review

While the amygdala is often implicated in the neurobiology of posttraumatic stress disorder (PTSD), the pattern of results remains mixed. One reason for this may be the heterogeneity of amygdala subnuclei and their functional connections. This review used PRISMA guidelines to synthesize research exploring the functional connectivity of three primary amygdala subnuclei, basolateral (BLA), centromedial (CMA), and superficial nuclei (SFA), in PTSD (N = 331) relative to trauma-exposed (N = 155) and non-trauma-exposed controls (N = 210). Although studies were limited (N = 11), preliminary evidence suggests that in PTSD compared to trauma-exposed controls, the BLA shows greater connectivity with the dorsal anterior cingulate, an area involved in salience detection. In PTSD compared to non-trauma-exposed controls, the BLA shows greater connectivity with the middle frontal gyrus, an area involved in attention. No other connections were replicated across studies. A secondary aim of this review was to outline the limitations of this field to better shape future research. Importantly, the results from this review indicate the need to consider potential mediators of amygdala subnuclei connectivity, such as trauma type and sex, when conducting such studies. They also highlight the need to be aware of the limited inferences we can make with such small samples that investigate small subcortical structures on low field strength magnetic resonance imaging scanners. Collectively, this review demonstrates the importance of exploring the differential connectivity of amygdala subnuclei to understand the pathophysiology of PTSD and stresses the need for future research to harness the strength of ultra-high field imaging to gain a more sensitive picture of the neural connectivity underlying PTSD.

A Cognitive Biotype of Depression and Symptoms, Behavior Measures, Neural Circuits, and Differential Treatment Outcomes: A Prespecified Secondary Analysis of a Randomized Clinical Trial

Importance

Cognitive deficits in depression have been associated with poor functional capacity, frontal neural circuit dysfunction, and worse response to conventional antidepressants. However, it is not known whether these impairments combine together to identify a specific cognitive subgroup (or "biotype") of individuals with major depressive disorder (MDD), and the extent to which these impairments mediate antidepressant outcomes.

Objective

To undertake a systematic test of the validity of a proposed cognitive biotype of MDD across neural circuit, symptom, social occupational function, and treatment outcome modalities.

Design, Setting, and Participants

This secondary analysis of a randomized clinical trial implemented data-driven clustering in findings from the International Study to Predict Optimized Treatment in Depression, a pragmatic biomarker trial in which patients with MDD were randomized in a 1:1:1 ratio to antidepressant treatment with escitalopram, sertraline, or venlafaxine extended-release and assessed at baseline and 8 weeks on multimodal outcomes between December 1, 2008, and September 30, 2013. Eligible patients were medication-free outpatients with nonpsychotic MDD in at least the moderate range, and were recruited from 17 clinical and academic practices; a subset of these patients underwent functional magnetic resonance imaging. This prespecified secondary analysis was performed between June 10, 2022, and April 21, 2023.

Main Outcomes and Measures

Pretreatment and posttreatment behavioral measures of cognitive performance across 9 domains, depression symptoms assessed using 2 standard depression scales, and psychosocial function assessed using the Social and Occupational Functioning Assessment Scale and World Health Organization Quality of Life scale were analyzed. Neural circuit function engaged during a cognitive control task was measured using functional magnetic resonance imaging.

Results

A total of 1008 patients (571 [56.6%] female; mean [SD] age, 37.8 [12.6] years) participated in the overall trial and 96 patients participated in the imaging substudy (45 [46.7%] female; mean [SD] age, 34.5 [13.5] years). Cluster analysis identified what may be referred to as a cognitive biotype of 27% of depressed patients with prominent behavioral impairment in executive function and response inhibition domains of cognitive control. This biotype was characterized by a specific profile of pretreatment depressive symptoms, worse psychosocial functioning (d = -0.25; 95% CI, -0.39 to -0.11; P < .001), and reduced activation of the cognitive control circuit (right dorsolateral prefrontal cortex: d = -0.78; 95% CI, -1.28 to -0.27; P = .003). Remission was comparatively lower in the cognitive biotype positive subgroup (73 of 188 [38.8%] vs 250 of 524 [47.7%]; P = .04) and cognitive impairments persisted regardless of symptom change (executive function: ηp2 = 0.241; P < .001; response inhibition: ηp2 = 0.750; P < .001). The extent of symptom and functional change was specifically mediated by change in cognition but not the reverse.

Conclusions and Relevance

Our findings suggest the presence of a cognitive biotype of depression with distinct neural correlates, and a functional clinical profile that responds poorly to standard antidepressants and instead may benefit from therapies specifically targeting cognitive dysfunction.

Trial Registration

ClinicalTrials.gov Identifier: NCT00693849.

Negative association between anterior insula activation and resilience during sustained attention: an fMRI twin study

BACKGROUND

While previous studies have suggested that higher levels of cognitive performance may be related to greater wellbeing and resilience, little is known about the associations between neural circuits engaged by cognitive tasks and wellbeing and resilience, and whether genetics or environment contribute to these associations.

METHODS

The current study consisted of 253 monozygotic and dizygotic adult twins, including a subsample of 187 early-life trauma-exposed twins, with functional Magnetic Resonance Imaging data from the TWIN-E study. Wellbeing was measured using the COMPAS-W Wellbeing Scale while resilience was defined as a higher level of positive adaptation (higher levels of wellbeing) in the presence of trauma exposure. We probed both sustained attention and working memory processes using a Continuous Performance Task in the scanner.

RESULTS

We found significant negative associations between resilience and activation in the bilateral anterior insula engaged during sustained attention. Multivariate twin modelling showed that the association between resilience and the left and right insula activation was mostly driven by common genetic factors, accounting for 71% and 87% of the total phenotypic correlation between these variables, respectively. There were no significant associations between wellbeing/resilience and neural activity engaged during working memory updating.

CONCLUSIONS

The findings suggest that greater resilience to trauma is associated with less activation of the anterior insula during a condition requiring sustained attention but not working memory updating. This possibly suggests a pattern of 'neural efficiency' (i.e. more efficient and/or attenuated activity) in people who may be more resilient to trauma.

Changes in neural responses during affective and non-affective tasks and improvement of posttraumatic stress disorder symptoms following trauma-focused psychotherapy

At least one-third posttraumatic stress disorder (PTSD) patients do not respond to trauma-focused psychotherapy (TF-psychotherapy), which is the treatment of choice for PTSD. To clarify the change mechanisms that may be associated with treatment response, this study examined changes in neural activations during affective and non-affective processing that occur with improvement of symptoms after TF-psychotherapy. This study assessed PTSD treatment-seeking patients (n = 27) prior to and after TF-psychotherapy using functional magnetic resonance imaging when they completed three tasks: (a) passive viewing of affective faces, (b) cognitive reappraisal of negative images, and (c) non-affective response inhibition. Patients then underwent 9 sessions of TF-psychotherapy, and were assessed on the Clinician-Administered PTSD Scale following treatment. Changes in neural responses in affect and cognitive processing regions-of-interest for each task were correlated with reduction of PTSD severity from pretreatment to posttreatment in the PTSD cohort. Data from 21 healthy controls was used for comparison. Improvement of symptoms in PTSD were associated with increased activation of left anterior insula, reductions in the left hippocampus and right posterior insula during viewing of supraliminally presented affective images, and reduced connectivity between the left hippocampus with the left amygdala and rostral anterior cingulate. Treatment response was also associated with reduced activation in the left dorsolateral prefrontal cortex during reappraisal of negative images. There were no associations between response and activation change during response inhibition. This pattern of findings indicates that improvement of PTSD symptoms following TF-psychotherapy is associated with changes in affective rather than non-affective processes. These findings accord with prevailing models that TF-psychotherapy promotes engagement and mastery of affective stimuli.Clinical Trials Registration: Trial Registration: Prospectively registered at Australian and New Zealand Clinical Trials Registry, ACTRN12612000185864 and ACTRN12609000324213. https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=83857.

Association of Neural Connectome With Early Experiences of Abuse in Adults

IMPORTANCE

More than 10% of children experience sexual, physical, or emotional abuse, and abuse experienced during sensitive neurodevelopmental periods is associated with a greater risk of psychiatric disorders.

OBJECTIVE

To investigate the extent to which a history of abuse is associated with alterations in the intrinsic functional connectome of the adult brain independent from the restriction of associated psychiatric conditions.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study assessed data from 768 adult participants from the greater Sydney, Australia, area who were included in the study without diagnostic restrictions and categorized based on a history of childhood sexual, physical, and/or emotional abuse. Data were collected from January 1, 2009, to December 31, 2015; data analysis was performed from October 1, 2020, to March 31, 2022.

MAIN OUTCOMES AND MEASURES

Outcomes were structured psychiatric interview responses, self-report of the frequency and extent of various types of negative experiences in childhood and adolescence, and intrinsic functional connectivity derived from 5 functional magnetic resonance imaging tasks and estimated among 436 brain regions, comprising intranetwork and internetwork connectivity of 8 large-scale brain networks.

RESULTS

Among the 647 individuals with usable data (330 female [51.0%]; mean [SD] age, 33.3 [12.0] years; age range, 18.2-69.2 years), history of abuse was associated with greater likelihood of a current psychiatric illness (odds ratio, 4.55; 95% CI, 3.07-6.72; P < .001) and with greater depressive, anxiety, and stress symptoms (mean difference, 20.4; 95% CI, 16.1-24.7; P < .001). An altered connectome signature of higher connectivity within somatomotor, dorsal, and ventral attention networks and between these networks and executive control and default mode networks was observed in individuals with a history of abuse experienced during childhood (n = 127) vs those without a history of abuse (n = 442; mean difference, 0.07; 95% CI, 0.05-0.08; familywise, Bonferroni-corrected P = .01; Cohen d = 0.82) and compared with those who experienced abuse in adolescence (n = 78; mean difference, 0.06; 95% CI, 0.04-0.08]; familywise, Bonferroni-corrected P < .001; Cohen d = 0.68). Connectome alterations were not observed for those who experienced abuse in adolescence. Connectivity of this signature was transdiagnostic and independent of the nature and frequency of abuse, sex, or current symptomatic state.

CONCLUSIONS AND RELEVANCE

Findings highlight the associations of exposure to abuse before and during adolescence with the whole-brain functional connectome. The experience of child abuse was found to be associated with physiologic changes in intrinsic connectivity, independent of psychopathology, in a way that may affect functioning of systems responsible for perceptual processing and attention.

Brainmarker-I Differentially Predicts Remission to Various Attention-Deficit/Hyperactivity Disorder Treatments: A Discovery, Transfer, and Blinded Validation Study

BACKGROUND

Attention-deficit/hyperactivity disorder is characterized by neurobiological heterogeneity, possibly explaining why not all patients benefit from a given treatment. As a means to select the right treatment (stratification), biomarkers may aid in personalizing treatment prescription, thereby increasing remission rates.

METHODS

The biomarker in this study was developed in a heterogeneous clinical sample (N = 4249) and first applied to two large transfer datasets, a priori stratifying young males (<18 years) with a higher individual alpha peak frequency (iAPF) to methylphenidate (N = 336) and those with a lower iAPF to multimodal neurofeedback complemented with sleep coaching (N = 136). Blinded, out-of-sample validations were conducted in two independent samples. In addition, the association between iAPF and response to guanfacine and atomoxetine was explored.

RESULTS

Retrospective stratification in the transfer datasets resulted in a predicted gain in normalized remission of 17% to 30%. Blinded out-of-sample validations for methylphenidate (n = 41) and multimodal neurofeedback (n = 71) corroborated these findings, yielding a predicted gain in stratified normalized remission of 36% and 29%, respectively.

CONCLUSIONS

This study introduces a clinically interpretable and actionable biomarker based on the iAPF assessed during resting-state electroencephalography. Our findings suggest that acknowledging neurobiological heterogeneity can inform stratification of patients to their individual best treatment and enhance remission rates.

Common and differential neural mechanisms underlying mood disorders

BACKGROUND

Despite homogenous clinical presentations between bipolar and unipolar disorders, there are distinct neurobiological differences. Chronicity of illness may be a factor impacting and sustaining certain neural features. The goal of this study was to investigate common and shared neural mechanisms underlying mood disorders, and possible sustained neural changes relating to illness chronicity by investigating a cohort of euthymic patients with bipolar disorder (BD), unipolar depression who had responded to treatment (treatment-sensitive depression, TSD), and a chronically treatment-resistant depressed (TRD) group.

METHODS

One hundred and seventy-two participants (40 BD, 39 TSD, 40 TRD, and 53 age-gender-matched healthy controls) underwent resting-state fMRI scans. Seed-based and independent component analyses were performed to investigate group differences in resting-state connectivity between the four groups.

RESULTS

All three clinical groups had significantly lower connectivity within the frontoparietal network (FPN) relative to controls. TRD and BD were significantly different from TSD (TRD, BD > TSD) but were not significantly different from each other. TRDs were also significantly different from both BD and TSD for salience network connectivity with the posterior cingulate (DMN) and the FPN with frontal pole (DMN). Additionally, the BD group exhibited greater DMN-FPN (sgACC-RDLPFC) connectivity relative to TRD, TSD, and controls, which was correlated with a previous number of depressive episodes, in the BD group only.

CONCLUSIONS

BD demonstrated shared and differential connectivity features relative to symptomatic TRD and euthymic TSD groups. The increased sgACC-RDLPFC connectivity in BD and its correlation with a number of depressive episodes could be a neural feature associated with illness chronicity.

A comparison of methods to harmonize cortical thickness measurements across scanners and sites

Results of neuroimaging datasets aggregated from multiple sites may be biased by site-specific profiles in participants' demographic and clinical characteristics, as well as MRI acquisition protocols and scanning platforms. We compared the impact of four different harmonization methods on results obtained from analyses of cortical thickness data: (1) linear mixed-effects model (LME) that models site-specific random intercepts (LMEINT), (2) LME that models both site-specific random intercepts and age-related random slopes (LMEINT+SLP), (3) ComBat, and (4) ComBat with a generalized additive model (ComBat-GAM). Our test case for comparing harmonization methods was cortical thickness data aggregated from 29 sites, which included 1,340 cases with posttraumatic stress disorder (PTSD) (6.2-81.8 years old) and 2,057 trauma-exposed controls without PTSD (6.3-85.2 years old). We found that, compared to the other data harmonization methods, data processed with ComBat-GAM was more sensitive to the detection of significant case-control differences (Χ2(3) = 63.704, p < 0.001) as well as case-control differences in age-related cortical thinning (Χ2(3) = 12.082, p = 0.007). Both ComBat and ComBat-GAM outperformed LME methods in detecting sex differences (Χ2(3) = 9.114, p = 0.028) in regional cortical thickness. ComBat-GAM also led to stronger estimates of age-related declines in cortical thickness (corrected p-values < 0.001), stronger estimates of case-related cortical thickness reduction (corrected p-values < 0.001), weaker estimates of age-related declines in cortical thickness in cases than controls (corrected p-values < 0.001), stronger estimates of cortical thickness reduction in females than males (corrected p-values < 0.001), and stronger estimates of cortical thickness reduction in females relative to males in cases than controls (corrected p-values < 0.001). Our results support the use of ComBat-GAM to minimize confounds and increase statistical power when harmonizing data with non-linear effects, and the use of either ComBat or ComBat-GAM for harmonizing data with linear effects.

A comparison of the functional connectome in mild traumatic brain injury and post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) and mild traumatic brain injury (mTBI) often co-occur in the context of threat to one's life. These conditions also have an overlapping symptomatology and include symptoms of anxiety, poor concentration and memory problems. A major challenge has been articulating the underlying neurobiology of these overlapping conditions. The primary aim of this study was to compare intrinsic functional connectivity between mTBI (without PTSD) and PTSD (without mTBI). The study included functional MRI data from 176 participants: 42 participants with mTBI, 67 with PTSD and a comparison group of 66 age and sex-matched healthy controls. We used network-based statistical analyses for connectome-wide comparisons of intrinsic functional connectivity between mTBI relative to PTSD and controls. Our results showed no connectivity differences between mTBI and PTSD groups. However, we did find that mTBI had significantly reduced connectivity relative to healthy controls within an extensive network of regions including default mode, executive control, visual and auditory networks. The mTBI group also displayed hyperconnectivity between dorsal and ventral attention networks and perceptual regions. The PTSD group also demonstrated abnormal connectivity within these networks relative to controls. Connectivity alterations were not associated with severity of PTSD or post-concussive symptoms in either clinical group. Taken together, the similar profiles of intrinsic connectivity alterations in these two conditions provide neural evidence that can explain, in part, the overlapping symptomatology between mTBI and PTSD.

Remodeling of the Cortical Structural Connectome in Posttraumatic Stress Disorder: Results From the ENIGMA-PGC Posttraumatic Stress Disorder Consortium

BACKGROUND

Posttraumatic stress disorder (PTSD) is accompanied by disrupted cortical neuroanatomy. We investigated alteration in covariance of structural networks associated with PTSD in regions that demonstrate the case-control differences in cortical thickness (CT) and surface area (SA).

METHODS

Neuroimaging and clinical data were aggregated from 29 research sites in >1300 PTSD cases and >2000 trauma-exposed control subjects (ages 6.2-85.2 years) by the ENIGMA-PGC (Enhancing Neuro Imaging Genetics through Meta Analysis-Psychiatric Genomics Consortium) PTSD working group. Cortical regions in the network were rank ordered by the effect size of PTSD-related cortical differences in CT and SA. The top-n (n = 2-148) regions with the largest effect size for PTSD > non-PTSD formed hypertrophic networks, the largest effect size for PTSD < non-PTSD formed atrophic networks, and the smallest effect size of between-group differences formed stable networks. The mean structural covariance (SC) of a given n-region network was the average of all positive pairwise correlations and was compared with the mean SC of 5000 randomly generated n-region networks.

RESULTS

Patients with PTSD, relative to non-PTSD control subjects, exhibited lower mean SC in CT-based and SA-based atrophic networks. Comorbid depression, sex, and age modulated covariance differences of PTSD-related structural networks.

CONCLUSIONS

Covariance of structural networks based on CT and cortical SA are affected by PTSD and further modulated by comorbid depression, sex, and age. The SC networks that are perturbed in PTSD comport with converging evidence from resting-state functional connectivity networks and networks affected by inflammatory processes and stress hormones in PTSD.

Intrinsic Functional Connectivity in the Default Mode Network Differentiates the Combined and Inattentive Attention Deficit Hyperactivity Disorder Types

Neuroimaging studies have revealed neurobiological differences in ADHD, particularly studies examining connectivity disruption and anatomical network organization. However, the underlying pathophysiology of ADHD types remains elusive as it is unclear whether dysfunctional network connections characterize the underlying clinical symptoms distinguishing ADHD types. Here, we investigated intrinsic functional network connectivity to identify neural signatures that differentiate the combined (ADHD-C) and inattentive (ADHD-I) presentation types. Applying network-based statistical (NBS) and graph theoretical analysis to task-derived intrinsic connectivity data from completed fMRI scans, we evaluated default mode network (DMN) and whole-brain functional network topology in a cohort of 34 ADHD participants (aged 8–17 years) defined using DSM-IV criteria as predominantly inattentive (ADHD-I) type (n = 15) or combined (ADHD-C) type (n = 19), and 39 age and gender-matched typically developing controls. ADHD-C were characterized from ADHD-I by reduced network connectivity differences within the DMN. Additionally, reduced connectivity within the DMN was negatively associated with ADHD-RS hyperactivity-impulsivity subscale score. Compared with controls, ADHD-C but not ADHD-I differed by reduced connectivity within the DMN; inter-network connectivity between the DMN and somatomotor networks; the DMN and limbic networks; and between the somatomotor and cingulo-frontoparietal, with ventral attention and dorsal attention networks. However, graph-theoretical measures did not significantly differ between groups. These findings provide insight into the intrinsic networks underlying phenotypic differences between ADHD types. Furthermore, these intrinsic functional connectomic signatures support neurobiological differences underlying clinical variations in ADHD presentations, specifically reduced within and between functional connectivity of the DMN in the ADHD-C type.

Abnormal habenula functional connectivity characterizes treatment-resistant depression

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Habenular hyper connectivity characterizes treatment-resistant depression.

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An interplay between reward and default mode networks is linked to suicidality.

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Abnormal habenula connectivity is a possible mechanism for anhedonia.

Background

A significant proportion of patients with major depressive disorder are resistant to antidepressant medication and psychological treatments. A core symptom of treatment-resistant depression (TRD) is anhedonia, or the inability to feel pleasure, which has been attributed to disrupted habenula function – a component of the reward network. This study aimed to map detailed neural circuitry architecture related to the habenula to identify neural mechanisms of TRD.

Methods

35 TRD patients, 35 patients with treatment-sensitive depression (TSD), and 38 healthy controls (HC) underwent resting-state functional magnetic resonance imaging. Functional connectivity analyses were performed using the left and right habenula as seed regions of interest, and the three groups were compared using whole-brain voxel-wise comparisons.

Results

The TRD group demonstrated hyperconnectivity of the left habenula to the left precuneus cortex and the right precentral gyrus, compared to the TSD group, and to the right precuneus cortex, compared to the TSD and HC groups. In contrast, TSD demonstrated hypoconnectivity than HC for both connectivity measures. These connectivity values were significantly higher in patients with a history of suicidal ideation.

Conclusions

This study provides evidence that, unlike TSD, TRD is characterized by hyperconnectivity of the left habenula particularly with regions of the default mode network. An increased interplay between reward and default mode networks is linked to suicidality and could be a possible mechanism for anhedonia in hard to treat depression.

Cognitive and Executive Contributions to Trail-Making Task Performance on Adolescents With and Without Attention Deficit Hyperactivity Disorder

OBJECTIVE

The trail making task is used to assess executive functioning in ADHD youth, yet has only been validated in adult populations. We compare the relative contributions of various cognitive measures to performance on a trail making task analog, the Switching of Attention (SoA) task, in typically-developing and ADHD adolescents.

METHOD

Participants were 160 adolescents with ADHD from the International Study to Predict Optimized Treatment-in ADHD, assessed at pretreatment baseline and 6-week medicated follow-up, and 160 matched typically-developing peers. Attention, processing speed, working memory, impulsivity, and motor speed were assessed using a cognitive battery.

RESULTS

Processing speed and working memory significantly contributed to SoA performance in ADHD, regardless of medication status. While medicated, motor speed also underpinned the prediction of most task measures. For typically-developing adolescents, sustained attention and working memory contributed to SoA performance.

CONCLUSION

Typically-developing, unmedicated and treated ADHD adolescents recruit different aspects of cognition during SoA completion.

Genetic variants associated with longitudinal changes in brain structure across the lifespan

Human brain structure changes throughout the lifespan. Altered brain growth or rates of decline are implicated in a vast range of psychiatric, developmental and neurodegenerative diseases. In this study, we identified common genetic variants that affect rates of brain growth or atrophy in what is, to our knowledge, the first genome-wide association meta-analysis of changes in brain morphology across the lifespan. Longitudinal magnetic resonance imaging data from 15,640 individuals were used to compute rates of change for 15 brain structures. The most robustly identified genes GPR139, DACH1 and APOE are associated with metabolic processes. We demonstrate global genetic overlap with depression, schizophrenia, cognitive functioning, insomnia, height, body mass index and smoking. Gene set findings implicate both early brain development and neurodegenerative processes in the rates of brain changes. Identifying variants involved in structural brain changes may help to determine biological pathways underlying optimal and dysfunctional brain development and aging.

Neural processes during response inhibition in complex posttraumatic stress disorder

BACKGROUND

A common feature of complex posttraumatic stress disorder (CPTSD) is impulsivity. Despite the importance of this characteristic in functional difficulties in CPTSD, little is known about its mechanisms. The aim of this study was to identify the distinctive neural profile of CPTSD during attempted inhibition.

METHODS

The present study examined functional alterations in neural networks involved in inhibitory control across functional magnetic resonance imaging (fMRI) and electroencephalogram (EEG) paradigms in CPTSD (n = 30), PTSD (n = 40), and healthy control (n = 40) participants who completed a Go/NoGo response inhibition task during separate fMRI and EEG sessions. Brain activations were calculated during the NoGo trials relative to the baseline to evaluate response inhibition functioning.

RESULTS

There was reduced bilateral thalamic activation in participants with CPTSD relative to PTSD and controls during inhibition trials, but no activation differences between PTSD and controls for this brain region. There were no differences in functional connectivity between the thalamus and other regions involved in cognitive control between groups. No differences were observed between groups on EEG responses.

CONCLUSIONS

These findings provide initial evidence of aberrant functioning in the neurocircuitry of inhibitory control, involving the thalamus, in CPTSD. This evidence suggests that CPTSD is distinguished from PTSD by impaired neural processes implicated in response inhibition.

Default-mode and fronto-parietal network connectivity during rest distinguishes asymptomatic patients with bipolar disorder and major depressive disorder

Bipolar disorder (BD) is commonly misdiagnosed as major depressive disorder (MDD). This is understandable, as depression often precedes mania and is otherwise indistinguishable in both. It is therefore imperative to identify neural mechanisms that can differentiate the two disorders. Interrogating resting brain neural activity may reveal core distinguishing abnormalities. We adopted an a priori approach, examining three key networks documented in previous mood disorder literature subserving executive function, salience and rumination that may differentiate euthymic BD and MDD patients. Thirty-eight patients with BD, 39 patients with MDD matched for depression severity, and 39 age-gender matched healthy controls, completed resting-state fMRI scans. Seed-based and data-driven Independent Component analyses (ICA) were implemented to examine group differences in resting-state connectivity (pFDR < 0.05). Seed analysis masks were target regions identified from the fronto-parietal (FPN), salience (SN) and default-mode (DMN) networks. Seed-based analyses identified significantly greater connectivity between the subgenual cingulate cortex (DMN) and right dorsolateral prefrontal cortex (FPN) in BD relative to MDD and controls. The ICA analyses also found greater connectivity between the DMN and inferior frontal gyrus, an FPN region in BD relative to MDD. There were also significant group differences across the three networks in both clinical groups relative to controls. Altered DMN-FPN functional connectivity is thought to underlie deficits in the processing, management and regulation of affective stimuli. Our results suggest that connectivity between these networks could potentially distinguish the two disorders and could be a possible trait mechanism in BD persisting even in the absence of symptoms.

Reappraisal-related neural predictors of treatment response to cognitive behavior therapy for post-traumatic stress disorder

BACKGROUND

Although trauma-focused cognitive behavior therapy (TF-CBT) is the frontline treatment for post-traumatic stress disorder (PTSD), one-third of patients are treatment non-responders. To identify neural markers of treatment response to TF-CBT when participants are reappraising aversive material.

METHODS

This study assessed PTSD patients (n = 37) prior to TF-CBT during functional magnetic brain resonance imaging (fMRI) when they reappraised or watched traumatic images. Patients then underwent nine sessions of TF-CBT, and were then assessed for symptom severity on the Clinician-Administered PTSD Scale. FMRI responses for cognitive reappraisal and emotional reactivity contrasts of traumatic images were correlated with the reduction of PTSD severity from pretreatment to post-treatment.

RESULTS

Symptom improvement was associated with decreased activation of the left amygdala during reappraisal, but increased activation of bilateral amygdala and hippocampus during emotional reactivity prior to treatment. Lower connectivity of the left amygdala to the subgenual anterior cingulate cortex, pregenual anterior cingulate cortex, and right insula, and that between the left hippocampus and right amygdala were also associated with symptom improvement.

CONCLUSIONS

These findings provide evidence that optimal treatment response to TF-CBT involves the capacity to engage emotional networks during emotional processing, and also to reduce the engagement of these networks when down-regulating emotions.

Intrinsic Functional Connectomes Characterize Neuroticism in Major Depressive Disorder and Predict Antidepressant Treatment Outcomes

BACKGROUND

Antidepressant efficacy in people with major depressive disorder (MDD) remains modest, yet identifying treatment predictive neurobiological markers may improve outcomes. While disruptions in functional connectivity within and between large-scale brain networks predict poorer treatment outcome, it is unclear whether higher trait neuroticism - which has been associated with generally poorer outcome - contributes to these disruptions and to antidepressant-specific treatment outcomes. Here, we used whole-brain functional connectivity analysis to identify a neural connectomic signature of neuroticism and tested whether this signature predicted antidepressant treatment outcome.

METHOD

Participants were 229 adults with MDD and 68 healthy controls who underwent functional MRI and were assessed on clinical features at baseline. MDD participants were then randomized to one of three commonly prescribed antidepressants and after 8 weeks completed a second functional MRI and were reassessed for depressive symptom remission/response. Baseline intrinsic functional connectivity between each pair of 436 brain regions were analysed using network-based statistics to identify connectomic features associated with neuroticism. Features were then assessed on their ability to predict treatment outcome and whether they changed after 8 weeks of treatment.

RESULTS

Higher baseline neuroticism was associated with greater connectivity within and between the salience, executive control, and somatomotor brain networks. Greater connectivity across these networks predicted poorer treatment outcome that was not mediated by baseline neuroticism, and connectivity strength decreased after antidepressant treatment.

CONCLUSIONS

Our findings demonstrate that neuroticism is associated with organization of intrinsic neural networks that predict treatment outcome, elucidating its biological underpinnings and opportunity for better treatment personalization.

Cortical volume abnormalities in posttraumatic stress disorder: an ENIGMA-psychiatric genomics consortium PTSD workgroup mega-analysis

Studies of posttraumatic stress disorder (PTSD) report volume abnormalities in multiple regions of the cerebral cortex. However, findings for many regions, particularly regions outside commonly studied emotion-related prefrontal, insular, and limbic regions, are inconsistent and tentative. Also, few studies address the possibility that PTSD abnormalities may be confounded by comorbid depression. A mega-analysis investigating all cortical regions in a large sample of PTSD and control subjects can potentially provide new insight into these issues. Given this perspective, our group aggregated regional volumes data of 68 cortical regions across both hemispheres from 1379 PTSD patients to 2192 controls without PTSD after data were processed by 32 international laboratories using ENIGMA standardized procedures. We examined whether regional cortical volumes were different in PTSD vs. controls, were associated with posttraumatic stress symptom (PTSS) severity, or were affected by comorbid depression. Volumes of left and right lateral orbitofrontal gyri (LOFG), left superior temporal gyrus, and right insular, lingual and superior parietal gyri were significantly smaller, on average, in PTSD patients than controls (standardized coefficients = -0.111 to -0.068, FDR corrected P values < 0.039) and were significantly negatively correlated with PTSS severity. After adjusting for depression symptoms, the PTSD findings in left and right LOFG remained significant. These findings indicate that cortical volumes in PTSD patients are smaller in prefrontal regulatory regions, as well as in broader emotion and sensory processing cortical regions.

No support for white matter connectivity differences in the combined and inattentive ADHD presentations

Evidence from functional neuroimaging studies support neural differences between the Attention Deficit Hyperactivity Disorder (ADHD) presentation types. It remains unclear if these neural deficits also manifest at the structural level. We have previously shown that the ADHD combined, and ADHD inattentive types demonstrate differences in graph properties of structural covariance suggesting an underlying difference in neuroanatomical organization. The goal of this study was to examine and validate white matter brain organization between the two subtypes using both scalar and connectivity measures of brain white matter. We used both tract-based spatial statistical (TBSS) and tractography analyses with network-based Statistics (NBS) and graph-theoretical analyses in a cohort of 35 ADHD participants (aged 8–17 years) defined using DSM-IV criteria as combined (ADHD-C) type (n = 19) or as predominantly inattentive (ADHD-I) type (n = 16), and 28 matched neurotypical controls. We performed TBSS analyses on scalar measures of fractional anisotropy (FA), mean (MD), radial (RD), and axial (AD) diffusivity to assess differences in WM between ADHD types and controls. NBS and graph theoretical analysis of whole brain inter-regional tractography examined connectomic differences and brain network organization, respectively. None of the scalar measures significantly differed between ADHD types or relative to controls. Similarly, there were no tractography connectivity differences between the two subtypes and relative to controls using NBS. Global and regional graph measures were also similar between the groups. A single significant finding was observed for nodal degree between the ADHD-C and controls, in the right insula (corrected p = .029). Our result of no white matter differences between the subtypes is consistent with most previous findings. These findings together might suggest that the white matter structural architecture is largely similar between the DSM-based ADHD presentations is similar to the extent of being undetectable with the current cohort size.

Neural activity during response inhibition in mild traumatic brain injury and posttraumatic stress disorder

Mild traumatic brain injury (mTBI) is often characterized by deficits in response inhibition, which can contribute to marked social and occupational dysfunction. mTBI often occurs in the context of psychologically traumatic events. This can cause posttraumatic stress disorder (PTSD), which also impedes response inhibition. The overlap or distinction in these inhibitory deficits in mTBI and PTSD is unclear. This study aimed to assess behavioral, neurophysiological, and neuroimaging indices of response inhibition in mTBI by also assessing these parameters in healthy controls (HC) and PTSD participants. Participants with mTBI (without PTSD) (n = 46), PTSD (without mTBI) (n = 41), and HC (n = 40) were assessed during a response inhibition task (the Go/NoGo task) during neuropsychological testing and separate functional magnetic imaging and event-related potentials sessions. PTSD symptom severity was assessed with the Clinician-Administered PTSD Scale. Both mTBI and PTSD participants performed more omission errors on the Go/NoGo task and were associated with greater N2 amplitude, greater left inferior parietal activation and reduced connectivity of the left inferior parietal cluster and left angular gyrus compared to HC. There were no differences between mTBI and PTSD on any of these measures. These findings highlight that both mTBI and PTSD contribute to neural dysfunction during response inhibition, and arguably these occur due to distinct mechanisms. In the context of the common comorbidity between these two conditions, strategies to address response inhibition deficits in mTBI may need to consider causative factors underpinning neurological insult of mTBI and psychological effects associated with PTSD.

The functional connectome in posttraumatic stress disorder

BACKGROUND

Previous fMRI studies of posttraumatic stress disorder (PTSD) have investigated region-specific alterations in intrinsic connectivity but connectome-wide changes in connectivity are yet to be characterized. Understanding the neurobiology of this is important to develop novel treatment interventions for PTSD. This study aims to identify connectome-wide disruptions in PTSD to provide a more comprehensive analysis of nseural networks in this disorder.

METHODS

A functional MRI scan was completed by 138 individuals (67 PTSD and 71 non-trauma-exposed healthy controls [HC]). For every individual, inter-regional intrinsic functional connectivity was estimated between 436 brain regions, comprising intra and inter-network connectivity of eight large-scale brain networks. Group-wise differences between PTSD and HC were investigated using network-based statistics at a family-wise error rate of p < 0.05. Significant network differences were then further investigated in 27 individuals with trauma exposure but no PTSD [TC]).

RESULTS

Compared to HC, PTSD displayed lower intrinsic functional connectivity in a network of 203 connections between 420 regions within and between mid-posterior default mode, central executive, limbic, visual and somatomotor regions. Additionally, PTSD displayed higher connectivity across a network of 50 connections from thalamic and limbic to sensory and default-mode regions. Connectivity in TC in both these networks was intermediate and significantly different to PTSD and HC.

CONCLUSION

A large-scale imbalance between hypoconnectivity of higher-order cortical networks and hyperconnectivity of emotional and arousal response systems seems to occur on a sliding scale from trauma exposure to clinical manifestation as PTSD. Novel interventions that target this systemic functional imbalance could provide potential mitigation of PTSD.

Investigating neural circuits of emotion regulation to distinguish euthymic patients with bipolar disorder and major depressive disorder

BACKGROUND

Up to 40% of patients with bipolar disorder (BD) are initially diagnosed as having major depressive disorder (MDD), and emotional lability is a key aspect of both sets of mood disorders. However, it remains unknown whether differences in the regulation of emotions through cognitive reappraisal may serve to distinguish BD and MDD. Therefore, we examined this question in euthymic BD and MDD patients.

METHODS

Thirty-eight euthymic BD, 33 euthymic MDD and 37 healthy control (HC) participants, matched for age, gender and depression severity, engaged in an emotion regulation (ER) cognitive reappraisal task during an fMRI scan were examined. Participants either reappraised (Think condition) or passively watched negative (Watch condition) or neutral (Neutral condition) pictures and rated their affect. Activation and connectivity analyses were used to examine group differences in reappraisal (Think vs Watch) and reactivity (Watch vs Neutral) conditions in ER-specific neural circuits.

RESULTS

Irrespective of group, participants rated most negatively the images during the Watch condition relative to Think and Neutral conditions, and more negatively to Think relative to Neutral. Notably, BD participants exhibited reduced subgenual anterior cingulate activation (sgACC) relative to MDD during reappraisal, but exhibited greater sgACC activation relative to MDD during reactivity, whereas MDD participants elicited greater activation in right amygdala relative to BD during reactivity. We found no group differences in task-related connectivity.

CONCLUSIONS

Euthymic BD and MDD patients engage differential brain regions to process and regulate emotional information. These differences could serve to distinguish the clinical groups and provide novel insights into the underlying pathophysiology of BD.

The distinctive neural circuitry of complex posttraumatic stress disorder during threat processing

BACKGROUND

There is controversy over the extent to which the new International Classification of Diseases (ICD-11) diagnosis of complex posttraumatic stress disorder (CPTSD) is distinct from posttraumatic stress disorder (PTSD). This study aimed to conduct the first investigation of distinctive neural processes during threat processing in CPTSD relative to PTSD.

METHOD

This cross-sectional functional magnetic resonance study included 99 participants who met criteria for PTSD (PTSD = 32, CPTSD = 28) and 39 trauma-exposed controls. PTSD was assessed with the Clinician-Administered PTSD Scale (CAPS). CPTSD was assessed with an adapted version of the International Trauma Questionnaire. Neural responses were measured across the brain while threat or neutral faces were presented at both supraliminal and subliminal levels.

RESULTS

During supraliminal presentations of threat stimuli, there was greater bilateral insula and right amygdala activation in CPTSD participants relative to PTSD. Reduced supraliminal right dorsolateral prefrontal cortex activation and increased subliminal amygdala and insula activation were observed as common dysfunction for both CPTSD and PTSD groups relative to trauma controls. There were no significant differences in terms of subliminal presentations and no differences in functional connectivity. Dissociative responses were positively associated with right insula activation (r = 0.347, p < 0.01).

CONCLUSIONS

These results provide the first evidence of distinct neural profiles of CPTSD and PTSD during threat processing. The observation of increased insula and right amygdala activation in CPTSD accords with the proposal that CPTSD is distinguished from PTSD by disturbances in emotion regulation and self-concept.

Distinct neural mechanisms of emotional processing in prolonged grief disorder

BACKGROUND

Prolonged grief disorder (PGD) has recently been recognized as a separate psychiatric diagnosis, despite controversy over the extent to which it is distinctive from posttraumatic stress disorder (PTSD) and major depressive disorder (MDD).

METHODS

This study investigated distinctive neural processes underpinning emotion processing in participants with PGD, PTSD, and MDD with functional magnetic resonance study of 117 participants that included PGD (n = 21), PTSD (n = 45), MDD (n = 26), and bereaved controls (BC) (n = 25). Neural responses were measured across the brain while sad, happy, or neutral faces were presented at both supraliminal and subliminal levels.

RESULTS

PGD had greater activation in the pregenual anterior cingulate cortex (pgACC), bilateral insula, bilateral dorsolateral prefrontal cortices and right caudate and also greater pgACC-right pallidum connectivity relative to BC during subliminal processing of happy faces. PGD was distinct relative to both PTSD and MDD groups with greater recruitment of the medial orbitofrontal cortex during supraliminal processing of sad faces. PGD were also distinct relative to MDD (but not PTSD) with greater activation in the left amygdala, caudate, and putamen during subliminal presentation of sad faces. There was no distinction between PGD, PTSD, and MDD during processing of happy faces.

CONCLUSIONS

These results provide initial evidence of distinct neural profiles of PGD relative to related psychopathological conditions, and highlight activation of neural regions implicated in reward networks. This pattern of findings validates current models of PGD that emphasize the roles of yearning and appetitive processes in PGD.

White matter anisotropy and response to cognitive behavior therapy for posttraumatic stress disorder

Trauma-focused cognitive behavior therapy (TF-CBT) is the gold standard treatment for posttraumatic stress disorder (PTSD), up to one-half of PTSD patients remain treatment non-responders. Although studies have used functional MRI to understand the neurobiology of treatment response, there is less understanding of the role of white matter brain structures in response to TF-CBT. Thirty-six treatment-seeking PTSD patients and 33 age-gender matched healthy controls completed diffusion-weighted imaging scans at baseline. Patients underwent nine sessions of TF-CBT treatment and PTSD symptom severity was assessed with the Clinician-Administered PTSD Scale before and after completing treatment. Patients were assessed to estimate the reduction in overall symptoms and also specifically fear and dysphoric symptoms of PTSD. Tract-based spatial statistical analyses were performed for the PTSD group to evaluate whole-brain correlations of fractional anisotropy (FA) with improvement in overall, fear, and dysphoric symptoms using non-parametric permutation inference testing (p_FWE < 0.05). Next, we evaluated if these significant measures also characterized PTSD from controls. Greater improvement in dysphoric symptoms was found correlated with lower FA in white matter regions associated with the limbic system, frontal cortex, thalamic association and projection fibers, corpus callosum, and tracts related to the brainstem. White matter anisotropy was not found associated with either overall or fear symptoms. FA in the significant clusters was similar between PTSD and controls. White-matter related to key functional regions may also play an important role in response to TF-CBT. Our results underscore the heterogeneity of PTSD and the need to evaluate distinct symptom phenotypes in treatment studies.

Neural correlates of emotional processing in panic disorder

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Abnormal non-conscious emotion processing in panic disorder.

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Impaired recruitment of implicit regulatory regions during affect processing.

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Lower pgACC activation in panic disorder for sad and happy faces.

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Deficits in key regulatory connections between inhibitory and emotion brain regions.

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Lower pgACC-amygdala connectivity for sad and fear faces.

Background

Deficits in emotional processing are conceptualized in prevailing models of anxiety to underpin key symptoms of panic disorder (PD). Neuroimaging studies show evidence of aberrant neural functioning in PD patients during emotional processing, however little is understood about how non-conscious emotional processing impacts neural processes.

Method

We examined activation and functional connectivity differences in brain regions involved in emotional processing between PD and healthy controls (HC) during subliminal and supraliminal presentations of facial emotions. Twenty-two PD and 33 HC participants were shown happy, sad, neutral, fear, anger and disgust facial expressions during functional magnetic resonance imaging using a 3T MRI scanner. We performed voxelwise ROI analyses at FWE-corrected p < 0.05 for main effects of group and group*emotion interactions.

Results

There was less pregenual anterior cingulate cortex (pgACC) activation to subliminal presentations of happy and sad faces in PD compared to HC participants (group*emotion). In addition, PD patients had less pgACC - right amygdala connectivity than HC participants during sad and fear subliminal processing (group*emotion). PD patients also exhibited lower right cerebellum activity across all supraliminal presentations of facial expressions compared to HC.

Conclusion

These findings suggest that there is aberrant neural processing in PD patients during both conscious and preconscious processing of both positive and negative stimuli, suggesting impaired recruitment of implicit regulatory networks during affective processing. It appears that PD patients may experience deficits in key regulatory connections between inhibitory and emotional neural networks at very early stages of processing of negative affective states.

Differential neural predictors of treatment response for fear and dysphoric features of posttraumatic stress disorder

BACKGROUND

Although trauma-focused cognitive behavioral therapy (TF-CBT) is the frontline treatment for posttraumatic stress disorder (PTSD), at least one-third of patients are treatment nonresponders. This study aimed to identify neural markers of treatment response, specifically the prediction of remission of specific PTSD symptoms.

METHODS

This study assessed PTSD treatment-seeking patients (n = 40) before TF-CBT during functional magnetic brain resonance imaging (fMRI) when they processed fearful, sad, happy, and neutral faces. Patients underwent nine sessions of TF-CBT and were independently assessed on the Clinician-Administered PTSD Scale (CAPS) following treatment. Treatment responders and nonresponders were compared with healthy controls (n = 40). The severity of PTSD was assessed with the CAPS. fMRI responses were calculated for each emotion face compared to neutral contrast, which were correlated with reduction in PTSD severity from pretreatment to posttreatment. Treatment response was categorized by at least 50% reduction in the severity of PTSD.

RESULTS

The activation of left insula during the processing of both sad and fearful faces was associated with a greater reduction of fear but not with dysphoric symptoms after treatment. Connectivity of the left insula to the pregenual anterior cingulate cortex was associated with poorer response to treatment. Responders and controllers had similar levels of activation and connectivity and were different from nonresponders.

CONCLUSIONS

Positive response to TF-CBT is predicted during emotion processing by normal levels of recruitment of neural networks implicated in emotional information. These findings suggest that distinct neural networks are predictive of PTSD fear and dysphoric symptom reduction following TF-CBT.

Intrinsic functional connectivity of the default mode and cognitive control networks relate to change in behavioral performance over two years

Understanding how brain circuitry mediates cognitive control of behavior is crucial for understanding both mental health and disease. Cognitive control describes the group of behaviors that guide goal-directed action such as sustaining attention, processing information and inhibiting impulsive responses. We rely on these behaviors for daily social, occupational and emotional functioning. Two brain networks, the cognitive control network (CCN) and default mode network (DMN), are thought to cooperate in an inverse relationship to support these functions. However, we do not yet know how connectivity within and between these networks directly relates to healthy cognitive control behaviors, and whether these interactions change over time. Here, we employed a longitudinal design to investigate if change in intrinsic connectivity in these networks will correlate with change in a range of cognitive control functions. Over two years, 109 healthy individuals, aged eight to thirty-eight, were tested twice using fMRI to assess intrinsic functional connectivity of the CCN and DMN and a validated cognitive battery. We found that increased within-network connectivity through central and left DMN was associated with increased memory performance. Additionally, decreased connectivity between posterior parietal CCN and DMN nodes and decreased connectivity between left and right dorsolateral prefrontal nodes was associated with increased cognitive performance. These findings were age and gender controlled, suggesting that age-independent plastic change in intrinsic connectivity through these networks directly relate to changing behavior. This has implications for targeting intrinsic connectivity as a possible mechanism to improve cognitive function.

Neurophysiological markers of attention distinguish bipolar disorder and unipolar depression

BACKGROUND

Attentional deficits are common in both symptomatic and symptom-remitted patients with bipolar disorder (BP) and major depressive disorder (MDD). However, whether the level of neurocognitive impairment in attentional processing is different between these two disorders, or not, is still unclear. Thus, we investigated the P300 event-related potential component as a biomarker of cognitive dysfunction to differentiate BP and MDD.

METHODS

Twenty-three age and gender matched BP, 20 MDD and 23 healthy controls (HC) were part of a discovery cohort to identify neurophysiological differences between groups and build a classification model of these disorders. The replication of this model was then tested in an independent second cohort of 17 BP, 19 MDD and 19 HC. All participants were symptom-remitted for at least two weeks. We compared neural responses to target stimuli during an auditory oddball task, computing peak amplitude and latency of the P300 component extracted from the midline centro-parietal electrode.

RESULTS

BP had significantly smaller P300 amplitudes compared to both MDD and HC, whereas there were no differences between MDD and HC. The differences between groups were replicated in the second cohort, however the accuracy level of the classification model was only 53.5%.

LIMITATIONS

Small sample sizes may have led to low accuracy levels of the classification model.

CONCLUSION

Specific neural mechanisms of attention and context updating seem not to recover with symptom remission in BP. These findings contribute to the detection of a potential electrophysiological marker for BP, which may allow its differentiation from unipolar major depressive disorder.

Intrinsic connectomes underlying response to trauma-focused psychotherapy in post-traumatic stress disorder

Although trauma-focused cognitive behavior therapy (TF-CBT) is the frontline treatment for post-traumatic stress disorder (PTSD), up to one-half of patients are treatment nonresponders. To understand treatment nonresponse, it is important to understand the neural mechanisms of TF-CBT. Here, we used whole-brain intrinsic functional connectivity analysis to identify neural connectomic signatures of treatment outcome. In total, 36 PTSD patients and 36 healthy individuals underwent functional MRI at pre-treatment baseline. Patients then underwent nine sessions of TF-CBT and completed clinical and follow-up MRIs. We used an established large-scale brain network atlas to parcellate the brain into 343 brain regions. Pairwise intrinsic task-free functional connectivity was calculated and used to identify pre-treatment connectomic features that were correlated with reduction of PTSD severity from pretreatment to post treatment. We formed a composite metric of intrinsic connections associated with therapeutic outcome, and then interrogated this composite metric to determine if it distinguished PTSD treatment responders and nonresponders from healthy control status and changed post treatment. Lower pre-treatment connectivity for the cingulo-opercular, salience, default mode, dorsal attention, and frontoparietal executive control brain networks was associated with treatment improvement. Treatment responders had lower while nonresponders had significantly greater connectivity than controls at pretreatment. With therapy, connectivity significantly increased for responders and decreased for nonresponders, while controls remain unchanged over this time period. We provide evidence that the intrinsic functional architecture of the brain, specifically connectivity within and between brain networks associated with external vigilance, self-awareness, and cognitive control, may characterize a positive response to TF-CBT for PTSD.

A Systematic Review of Imaging Studies in the Combined and Inattentive Subtypes of Attention Deficit Hyperactivity Disorder

Objective: Insights to underlying neural mechanisms in attention deficit hyperactivity disorder (ADHD) have emerged from neuroimaging research; however, the neural mechanisms that distinguish ADHD subtypes remain inconclusive.

Method: We reviewed 19 studies integrating magnetic resonance imaging [MRI; structural (sMRI), diffusion, functional MRI (fMRI)] findings into a framework exploring pathophysiological mechanisms underlying the combined (ADHD-C) and predominantly inattentive (ADHD-I) ADHD subtypes.

Results: Despite equivocal structural MRI results, findings from fMRI and DTI imaging modalities consistently implicate disrupted connectivity in regions and tracts involving frontal striatal thalamic in ADHD-C and frontoparietal neural networks in ADHD-I. Alterations of the default mode, cerebellum, and motor networks in ADHD-C and cingulo-frontoparietal attention and visual networks in ADHD-I highlight network organization differences between subtypes.

Conclusion: Growing evidence from neuroimaging studies highlight neurobiological differences between ADHD clinical subtypes, particularly from a network perspective. Understanding brain network organization and connectivity may help us to better conceptualize the ADHD types and their symptom variability.

Investigating the neural basis of cognitive control dysfunction in mood disorders

OBJECTIVES

Dysfunction of cognitive control is a feature of both bipolar disorder (BP) and major depression (MDD) and persists through to remission. However, it is unknown whether these disorders are characterized by common or distinct disruptions of cognitive control function and its neural basis. We investigated this gap in knowledge in asymptomatic BP and MDD participants, interpreted within a framework of normative function.

METHODS

Participants underwent fMRI scans engaging cognitive control through a working memory task and completed a cognitive battery evaluating performance across multiple subdomains of cognitive control, including attention, impulsivity, processing speed, executive function, and memory. Analysis was performed in two stages: (i) cognitive control-related brain activation and deactivation were correlated with cognitive control performance in 115 healthy controls (HCs), then, (ii) significantly correlated regions from (i) were compared between 25 asymptomatic BP, 25 remitted MDD, and with 25 different HCs, matched for age and gender.

RESULTS

Impulsivity and executive function performance were significantly worse in BP compared to both MDD and HCs. Both BP and MDD had significantly poorer memory performance compared to HCs. Greater deactivation of the medial prefrontal cortex (MPFC) during the fMRI task was associated with better executive function in healthy controls. Significantly less deactivation in this region was present in both BP and MDD compared to HCs.

CONCLUSIONS

Failure to deactivate the MPFC, a key region of the default mode network, during working memory processing is a shared neural feature present in both bipolar and major depression and could be a source of common cognitive dysfunction.

Connectivity of the Cognitive Control Network During Response Inhibition as a Predictive and Response Biomarker in Major Depression: Evidence From a Randomized Clinical Trial

BACKGROUND

In treating major depressive disorder, we lack tests anchored in neurobiology that predict antidepressant efficacy. Cognitive impairments are a particularly disabling feature of major depressive disorder. We tested whether functional connectivity during a response-inhibition task can predict response to antidepressants and whether its changes over time are correlated to symptom changes.

METHODS

We analyzed data from outpatients with major depressive disorder (n = 124) randomized to receive escitalopram, sertraline, or venlafaxine (8 weeks) and healthy control subjects (n = 59; age 18-65 years). Before and after treatment, participants were interviewed and scanned using functional magnetic resonance imaging, and functional connectivity was measured using generalized psychophysiological interaction during response inhibition (Go-NoGo task). We investigated the interaction between treatment type and response (≥50% reduction on self-reported symptoms), coupling differences between responders and nonresponders at baseline, their correlation with symptom improvement, and their changes in time.

RESULTS

During response inhibition, connectivity between the dorsolateral prefrontal cortex/supramarginal gyrus and supramarginal gyrus/middle temporal gyrus was associated with response to sertraline and venlafaxine, but not escitalopram. Sertraline responders had higher functional connectivity between these regions compared with nonresponders, whereas venlafaxine responders had lower functional connectivity. For sertraline, attenuation of connectivity in the precentral and superior temporal gyri correlated with posttreatment symptom improvement. For venlafaxine, enhancement of connectivity between the orbitofrontal cortex and subcortical regions correlated with symptom improvement.

CONCLUSIONS

Connectivity of the cognitive control circuit during response inhibition selectively and differentially predicts antidepressant treatment response and correlates with symptom improvement. These quantitative markers tied to the neurobiology of cognitive features of depression could be used translationally to predict and evaluate treatment response.

Characterizing neurocognitive markers of familial risk for depression using multi-modal imaging, behavioral and self-report measures

BACKGROUND

Major depressive disorder (MDD) is associated with poorer behavioral performance in domains of working memory and associated cognitive systems for cognitive control and attention. Functional neuroimaging studies show altered functioning in MDD in frontal executive control circuits implicated in these cognitive processes. It is not yet known whether poor cognitive performance involving these circuits is part of the familial risk for MDD, and we addressed this issue using a multi-modal imaging, behavioral and self-report approach in unaffected first-degree relatives of parent probands with MDD.

METHODS

72 unaffected adult first-degree relatives of probands with MDD (mean age 30.5 ± 13.4 years) with and 66 case-wise matched non-relative controls underwent functional magnetic resonance imaging during performance of 'n-back' working memory task, a Go/No-go task assessing cognitive control and an Auditory Oddball test of selective attention. Groups were compared on imaging data analyzed voxel wise with a focus on dorsolateral prefrontal cortex, anterior cingulate cortex and insula regions of interest, and on corresponding behavioral accuracy and reaction time data. Symptoms were assessed using self-report scales.

RESULTS

Relatives were distinguished by comparatively decreased activation in the left dorsolateral prefrontal cortex (DLPFC) during updating of working memory. Behaviorally, relatives also showed more errors of omission during working memory updating. DLPFC hypo-activation was associated with greater depressive symptom severity.

CONCLUSIONS

Deficits in cognitive processing may be part of the profile of familial risk for depression, preceding illness onset, specifically in the domain of working memory.

The effects of bullying in depression on white matter integrity

Individuals with elevated symptoms of depression exhibit alterations in white matter integrity, including lower fractional anisotropy (FA) evident on diffusion tensor imaging (DTI). Similarly, individuals with a history of early life stress (ELS) exhibit lower FA in the white matter independent of concurrent depression. Prior studies have not determined whether the neuroimaging signature of comorbid ELS and adult depression differs from the pattern of brain white matter changes associated with depression in the absence of self-reported ELS. The current study examined FA in multiple white matter tracts in 186 adults (93 males; 93 females) with a current diagnosis of major depressive disorder, including 88 who reported a history of bullying before the age of 18 (43 males; 45 females). All patients were antidepressant medication free at the time of testing. After adjusting for demographics and other ELS subtypes, participants with a history of bullying exhibited increased FA in the right medial lemniscus (p =.039) and left posterior corona radiata (p =.008) compared to participants with depression but no self-reported history of bullying. Both groups endorsed similar levels of depression. Group differences were most pronounced among individuals who endorsed bullying in late adolescence (14-17 years of age). Results suggest bullying in late adolescence is uniquely related to abnormal brain microstructure among individuals with current diagnoses of depression, possibly due to an overactive fear response. Further work is needed to differentiate why ELS within bullying is associated with higher FA.

Gender-specific structural abnormalities in major depressive disorder revealed by fixel-based analysis

BACKGROUND

Major depressive disorder (MDD) is a chronic disease with a large global impact. There are currently no clinically useful predictors of treatment outcome, and the development of biomarkers to inform clinical treatment decisions is highly desirable.

METHODS

In this exploratory study we performed fixel-based analysis of diffusion MRI data from the International Study to Predict Optimized Treatment in Depression with the aim of identifying novel biomarkers at baseline that may relate to diagnosis and outcome to treatment with antidepressant medications. Analyses used MR data from individuals with MDD (n = 221) and healthy controls (n = 67).

RESULTS

We show focal, gender-specific differences in the anterior limb of the internal capsule (males) and bilaterally in the genu of the corpus callosum (females) associated with diagnosis. Lower fibre cross-section in the tapetum, the conduit between the right and left hippocampi, were also associated with a decreased probability of remission. Analysis of conventional fractional anisotropy showed scattered abnormalities in the corona radiata, cerebral peduncles and mid-brain which were much lower in total volume compared to fixel-based analysis.

CONCLUSIONS

Fixel-based analysis appeared to identify different underlying abnormalities than conventional tensor-based metrics, with almost no overlap between significant regions. We show that MDD is associated with gender specific abnormalities in the genu of the corpus callosum (females) and in the anterior limb of the internal capsule (males), as well as gender-independent differences in the tapetum that predict remission. Diffusion MRI may play a key role in future guidance of clinical decision-making for MDD.

Understanding the neural mechanisms of lisdexamfetamine dimesylate (LDX) pharmacotherapy in Binge Eating Disorder (BED): a study protocol

BACKGROUND

The efficacy and safety of Lisdexamfetamine dimesylate (LDX) in the treatment of moderate to severe binge eating disorder (BED) has been demonstrated in multiple randomised clinical trials. Despite this, little is known about how LDX acts to improve binge eating symptoms. This study aims to provide a comprehensive understanding of the neural mechanisms by which LDX improves symptoms of BED. We hypothesise that LDX will act by normalising connectivity within neural circuits responsible for reward and impulse control, and that this normalisation will correlate with reduced binge eating episodes.

METHODS

This is an open-label Phase 4 clinical trial of LDX in adults with moderate to severe BED. Enrolment will include 40 adults with moderate to severe BED aged 18-40 years and Body Mass Index (BMI) of 20-45 kg/m², and 22 healthy controls matched for age, gender and BMI. Clinical interview and validated scales are used to confirm diagnosis and screen for exclusion criteria, which include comorbid anorexia nervosa or bulimia nervosa, use of psychostimulants within the past 6 months, and current use of antipsychotics or noradrenaline reuptake inhibitors. Baseline assessments include clinical symptoms, multimodal neuroimaging, cognitive assessment of reward sensitivity and behavioural inhibition, and an (optional) genetic sample. A subset of these assessments are repeated after eight weeks of treatment with LDX titrated to either 50 or 70 mg. The primary outcome measures are resting-state intrinsic connectivity and the number of binge eating episodes. Analyses will be applied to resting-state fMRI data to characterise pharmacological effects across the functional connectome, and assess correlations with symptom measure changes. Comparison of neural measures between controls and those with BED post-treatment will also be performed to determine whether LDX normalises brain function.

DISCUSSION

First enrolment was in May 2018, and is ongoing. This study is the first comprehensive investigation of the neurobiological changes that occur with LDX treatment in adults with moderate to severe BED.

TRIAL REGISTRATION

ACTRN12618000623291, Australian and New Zealand Clinical Trials Registry URL: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=374913&isReview=true. Date of Registration: 20 April 2018.

A negative association between brainstem pontine grey-matter volume, well-being and resilience in healthy twins

Background

Associations between well-being, resilience to trauma and the volume of grey-matter regions involved in affective processing (e.g., threat/reward circuits) are largely unexplored, as are the roles of shared genetic and environmental factors derived from multivariate twin modelling.

Methods

This study presents, to our knowledge, the first exploration of well-being and volumes of grey-matter regions involved in affective processing using a region-of-interest, voxel-based approach in 263 healthy adult twins (60% monozygotic pairs, 61% females, mean age 39.69 yr). To examine patterns for resilience (i.e., positive adaptation following adversity), we evaluated associations between the same brain regions and well-being in a trauma-exposed subgroup.

Results

We found a correlated effect between increased well-being and reduced grey-matter volume of the pontine nuclei. This association was strongest for individuals with higher resilience to trauma. Multivariate twin modelling suggested that the common variance between the pons volume and well-being scores was due to environmental factors.

Limitations

We used a cross-sectional sample; results need to be replicated longitudinally and in a larger sample.

Conclusion

Associations with altered grey matter of the pontine nuclei suggest that basic sensory processes, such as arousal, startle, memory consolidation and/or emotional conditioning, may have a role in well-being and resilience.

Diffusion Tensor Imaging Analysis of Mild Traumatic Brain Injury and Posttraumatic Stress Disorder

BACKGROUND

Debate exists over the extent to which dysfunctions arising from mild traumatic brain injury (mTBI) are distinct from posttraumatic stress disorder (PTSD).

METHODS

This study investigated 1) the white matter integrity of participants with either mTBI or PTSD, and 2) the relationship between white matter integrity and postconcussive syndrome. The sample comprised 110 civilians (mTBI group = 40; PTSD group = 32; age- and sex-matched trauma-exposed control subjects = 38) recruited from community advertising. Indicators of white matter abnormalities were fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity. PTSD symptoms were indexed by the Clinician-Administered PTSD Scale, and postconcussive symptoms were assessed using the Somatic and Psychological Health Report measure.

RESULTS

Fractional anisotropy was reduced in mTBI participants in the corpus callosum, tracts of the brainstem, projection fibers, association fibers, and limbic fibers compared with both PTSD and trauma-exposed control subjects. This decrease in fractional anisotropy was observed in the context of concurrent changes in radial diffusivity, axial diffusivity, and mean diffusivity. Postconcussive symptoms were largely explained by PTSD severity rather than by changes in brain white matter. mTBI appears to be characterized by distinct reductions in white matter integrity, and this cannot be attributed to PTSD.

CONCLUSIONS

PTSD symptoms appear to be more strongly associated with postconcussive syndrome than with white matter compromise. These findings extend epidemiological evidence of the relative associations of PTSD and mTBI with postconcussive syndrome.

Amygdala Activation and Connectivity to Emotional Processing Distinguishes Asymptomatic Patients With Bipolar Disorders and Unipolar Depression

BACKGROUND

Mechanistically based neural markers, such as amygdala reactivity, offer one approach to addressing the challenges of differentiating bipolar and unipolar depressive disorders independently from mood state and acute symptoms. Although emotion-elicited amygdala reactivity has been found to distinguish patients with bipolar depression from patients with unipolar depression, it remains unknown whether this distinction is traitlike and present in the absence of an acutely depressed mood. We addressed this gap by investigating patients with bipolar disorder (BP) and unipolar major depressive disorder (MDD) in remission.

METHODS

Supraliminal and subliminal processing of faces exhibiting threat, sad, happy, and neutral emotions during functional magnetic resonance imaging was completed by 73 participants (23 BP patients and 25 MDD patients matched for age and gender, number of depressive episodes and severity; 25 age- and gender-matched healthy control subjects). We compared groups for activation and connectivity for the amygdala.

RESULTS

BP patients had lower left amygdala activation than MDD patients during supraliminal and subliminal threat, sad, and neutral emotion processing and for subliminal happy faces. BP patients also exhibited lower amygdala connectivity to the insula and hippocampus for threat and to medial orbitofrontal cortex for happy supraliminal and subliminal processing. BP patients also demonstrated greater amygdala-insula connectivity for sad supraliminal and subliminal face processing. Both patient groups were distinct from control subjects across several measures for activation and connectivity.

CONCLUSIONS

Independent of valence or level of emotional awareness, amygdala activation and connectivity during facial emotion processing can distinguish BP patients and MDD patients. These findings provide evidence that this neural substrate could be a potential trait marker to differentiate these two disorders largely independent of illness state.

Effects of methylphenidate on cognition and behaviour in children with neurofibromatosis type 1: a study protocol for a randomised placebo-controlled crossover trial

INTRODUCTION

Dopamine dysregulation has been identified as a key modulator of behavioural impairment in neurofibromatosis type 1 (NF1) and a potential therapeutic target. Preclinical research demonstrates reduced dopamine in the brains of genetically engineered NF1 mouse strains is associated with reduced spatial-learning and attentional dysfunction. Methylphenidate, a stimulant medication that increases dopaminergic and noradrenergic neurotransmission, rescued the behavioural and dopamine abnormalities. Although preliminary clinical trials have demonstrated that methylphenidate is effective in treating attention deficit hyperactivity disorder (ADHD) symptoms in children with NF1, its therapeutic effect on cognitive performance is unclear. The primary aim of this clinical trial is to assess the efficacy of methylphenidate for reducing attention deficits, spatial working memory impairments and ADHD symptoms in children with NF1.

METHODS AND ANALYSIS

A randomised, double-blind, placebo-controlled trial of methylphenidate with a two period crossover design. Thirty-six participants with NF1 aged 7-16 years will be randomised to one of two treatment sequences: 6 weeks of methylphenidate followed by 6 weeks of placebo or; 6 weeks of placebo followed by 6 weeks of methylphenidate. Neurocognitive and behavioural outcomes as well as neuroimaging measures will be completed at baseline and repeated at the end of each treatment condition (week 6, week 12). Primary outcome measures are omission errors on the Conners Continuous Performance Test-II (attention), between-search errors on the Spatial Working Memory task from the Cambridge Neuropsychological Test Automated Battery (spatial working memory) and the Inattentive and Hyperactivity/Impulsivity Symptom Scales on the Conners 3-Parent. Secondary outcomes will examine the effect of methylphenidate on executive functions, attention, visuospatial skills, behaviour, fine-motor skills, language, social skills and quality of life.

ETHICS AND DISSEMINATION

This trial has hospital ethics approval and the results will be disseminated through peer-reviewed publications and international conferences.

TRIAL REGISTRATION NUMBER

ACTRN12611000765921.