Mild White Matter Changes in Un-medicated Obsessive-Compulsive Disorder Patients and Their Unaffected Siblings

Comprehensive Assessment of Ischemic Stroke in Nonhuman Primates: Neuroimaging, Behavioral, and Serum Proteomic Analysis

Ischemic strokes, prevalence and impactful, underscore the necessity of advanced research models closely resembling human physiology. Our study utilizes nonhuman primates (NHPs) to provide a detailed exploration of ischemic stroke, integrating neuroimaging data, behavioral outcomes, and serum proteomics to elucidate the complex interplay of factors involved in stroke pathophysiology. We observed a consistent pattern in infarct volume, peaking at 1-month postmiddle cerebral artery occlusion (MCAO) and then stabilized. This pattern was strongly correlated to notable changes in motor function and working memory performance. Using diffusion tensor imaging (DTI), we detected significant alterations in fractional anisotropy (FA) and mean diffusivity (MD) values, signaling microstructural changes in the brain. These alterations closely correlated with the neurological and cognitive deficits that we observed, highlighting the sensitivity of DTI metrics in stroke assessment. Behaviorally, the monkeys exhibited a reliance on their unaffected limb for compensatory movements, a common response to stroke impairment. This adaptation, along with consistent DTI findings, suggests a significant impact of stroke on motor function and spatial perception. Proteomic analysis through MS/MS functional enrichment identified two distinct groups of proteins with significant changes post-MCAO. Notably, MMP9, THBS1, MB, PFN1, and YWHAZ were identified as potential biomarkers and therapeutic targets for ischemic stroke. Our results underscore the complex nature of stroke and advocate for an integrated approach, combining neuroimaging, behavioral studies, and proteomics, for advancing our understanding and treatment of this condition.

Age of onset of obsessive-compulsive disorder differentially affects white matter microstructure

Previous diffusion MRI studies have reported mixed findings on white matter microstructure alterations in obsessive-compulsive disorder (OCD), likely due to variation in demographic and clinical characteristics, scanning methods, and underpowered samples. The OCD global study was created across five international sites to overcome these challenges by harmonizing data collection to identify consistent brain signatures of OCD that are reproducible and generalizable. Single-shell diffusion measures (e.g., fractional anisotropy), multi-shell Neurite Orientation Dispersion and Density Imaging (NODDI) and fixel-based measures, were extracted from skeletonized white matter tracts in 260 medication-free adults with OCD and 252 healthy controls. We additionally performed structural connectome analysis. We compared cases with controls and cases with early (<18) versus late (18+) OCD onset using mixed-model and Bayesian multilevel analysis. Compared with healthy controls, adult OCD individuals showed higher fiber density in the sagittal stratum (B[SE] = 0.10[0.05], P = 0.04) and credible evidence for higher fiber density in several other tracts. When comparing early (n = 145) and late-onset (n = 114) cases, converging evidence showed lower integrity of the posterior thalamic radiation -particularly radial diffusivity (B[SE] = 0.28[0.12], P = 0.03)-and lower global efficiency of the structural connectome (B[SE] = 15.3[6.6], P = 0.03) in late-onset cases. Post-hoc analyses indicated divergent direction of effects of the two OCD groups compared to healthy controls. Age of OCD onset differentially affects the integrity of thalamo-parietal/occipital tracts and the efficiency of the structural brain network. These results lend further support for the role of the thalamus and its afferent fibers and visual attentional processes in the pathophysiology of OCD.

Impact of cognition-related single nucleotide polymorphisms on brain imaging phenotype in Parkinson's disease

Multiple single nucleotide polymorphisms may contribute to cognitive decline in Parkinson's disease. However, the mechanism by which these single nucleotide polymorphisms modify brain imaging phenotype remains unclear. The aim of this study was to investigate the potential effects of multiple single nucleotide polymorphisms on brain imaging phenotype in Parkinson's disease. Forty-eight Parkinson's disease patients and 39 matched healthy controls underwent genotyping and 7T magnetic resonance imaging. A cognitive-weighted polygenic risk score model was designed, in which the effect sizes were determined individually for 36 single nucleotide polymorphisms. The correlations between polygenic risk score, neuroimaging features, and clinical data were analyzed. Furthermore, individual single nucleotide polymorphism analysis was performed to explore the main effects of genotypes and their interactive effects with Parkinson's disease diagnosis. We found that, in Parkinson's disease, the polygenic risk score was correlated with the neural activity of the hippocampus, parahippocampus, and fusiform gyrus, and with hippocampal-prefrontal and fusiform-temporal connectivity, as well as with gray matter alterations in the orbitofrontal cortex. In addition, we found that single nucleotide polymorphisms in α-synuclein (SNCA) were associated with white matter microstructural changes in the superior corona radiata, corpus callosum, and external capsule. A single nucleotide polymorphism in catechol-O-methyltransferase was associated with the neural activities of the lingual, fusiform, and occipital gyri, which are involved in visual cognitive dysfunction. Furthermore, DRD3 was associated with frontal and temporal lobe function and structure. In conclusion, imaging genetics is useful for providing a better understanding of the genetic pathways involved in the pathophysiologic processes underlying Parkinson's disease. This study provides evidence of an association between genetic factors, cognitive functions, and multi-modality neuroimaging biomarkers in Parkinson's disease.

Abnormal white-matter rich-club organization in obsessive-compulsive disorder

Rich‐club organization is key to efficient global neuronal signaling and integration of information. Alterations interfere with higher‐order cognitive processes, and are common to several psychiatric and neurological conditions. A few studies examining the structural connectome in obsessive–compulsive disorder (OCD) suggest lower efficiency of information transfer across the brain. However, it remains unclear whether this is due to alterations in rich‐club organization. In the current study, the structural connectome of 28 unmedicated OCD patients, 8 of their unaffected siblings and 28 healthy controls was reconstructed by means of diffusion‐weighted imaging and probabilistic tractography. Topological and weighted measures of rich‐club organization and connectivity were computed, alongside global and nodal measures of network integration and segregation. The relationship between clinical scores and network properties was explored. Compared to healthy controls, OCD patients displayed significantly lower topological and weighted rich‐club organization, allocating a smaller fraction of all connection weights to the rich‐club core. Global clustering coefficient, local efficiency, and clustering of nonrich club nodes were significantly higher in OCD patients. Significant three‐group differences emerged, with siblings displaying highest and lowest values in different measures. No significant correlation with any clinical score was found. Our results suggest weaker structural connectivity between rich‐club nodes in OCD patients, possibly resulting in lower network integration in favor of higher network segregation. We highlight the need of looking at network‐based alterations in brain organization and function when investigating the neurobiological basis of this disorder, and stimulate further research into potential familial protective factors against the development of OCD.

Aberrant rich club organization in patients with obsessive-compulsive disorder and their unaffected first-degree relatives

Recent studies suggested that the rich club organization promoting global brain communication and integration of information, may be abnormally increased in obsessive-compulsive disorder (OCD). However, the structural and functional basis of this organization is still not very clear. Given the heritability of OCD, as suggested by previous family-based studies, we hypothesize that aberrant rich club organization may be a trait marker for OCD. In the present study, 32 patients with OCD, 30 unaffected first-degree relatives (FDR) and 32 healthy controls (HC) underwent diffusion tensor imaging (DTI) and functional magnetic resonance imaging (fMRI). We examined the structural rich club organization and its interrelationship with functional coupling. Our results showed that rich club and peripheral connection strength in patients with OCD was lower than in HC, while it was intermediate in FDR. Finally, the coupling between structural and functional connections of the rich club, was decreased in FDR but not in OCD relative to HC, which suggests a buffering mechanism of brain functions in FDR. Overall, our findings suggest that alteration of the rich club organization may reflect a vulnerability biomarker for OCD, possibly buffered by structural and functional coupling of the rich club.

Enhancing neuroimaging genetics through meta-analysis for Tourette syndrome (ENIGMA-TS): A worldwide platform for collaboration

Tourette syndrome (TS) is characterized by multiple motor and vocal tics, and high-comorbidity rates with other neuropsychiatric disorders. Obsessive compulsive disorder (OCD), attention deficit hyperactivity disorder (ADHD), autism spectrum disorders (ASDs), major depressive disorder (MDD), and anxiety disorders (AXDs) are among the most prevalent TS comorbidities. To date, studies on TS brain structure and function have been limited in size with efforts mostly fragmented. This leads to low-statistical power, discordant results due to differences in approaches, and hinders the ability to stratify patients according to clinical parameters and investigate comorbidity patterns. Here, we present the scientific premise, perspectives, and key goals that have motivated the establishment of the Enhancing Neuroimaging Genetics through Meta-Analysis for TS (ENIGMA-TS) working group. The ENIGMA-TS working group is an international collaborative effort bringing together a large network of investigators who aim to understand brain structure and function in TS and dissect the underlying neurobiology that leads to observed comorbidity patterns and clinical heterogeneity. Previously collected TS neuroimaging data will be analyzed jointly and integrated with TS genomic data, as well as equivalently large and already existing studies of highly comorbid OCD, ADHD, ASD, MDD, and AXD. Our work highlights the power of collaborative efforts and transdiagnostic approaches, and points to the existence of different TS subtypes. ENIGMA-TS will offer large-scale, high-powered studies that will lead to important insights toward understanding brain structure and function and genetic effects in TS and related disorders, and the identification of biomarkers that could help inform improved clinical practice.

Abnormal brain functional network dynamics in obsessive-compulsive disorder patients and their unaffected first-degree relatives

We utilized dynamic functional network connectivity (dFNC) analysis to compare participants with obsessive–compulsive disorder (OCD) with their unaffected first‐degree relative (UFDR) and healthy controls (HC). Resting state fMRI was performed on 46 OCD, 24 UFDR, and 49 HCs, along with clinical assessments. dFNC analyses revealed two distinct connectivity states: a less frequent, integrated state characterized by the predominance of between‐network connections (State I), and a more frequent, segregated state with strong within‐network connections (State II). OCD patients spent more time in State II and less time in State I than HC, as measured by fractional windows and mean dwell time. Time in each state for the UFDR were intermediate between OCD patients and HC. Within the OCD group, fractional windows of time spent in State I was positively correlated with OCD symptoms (as measured by the obsessive compulsive inventory‐revised [OCI‐R], r = .343, p<.05, FDR correction) and time in State II was negatively correlated with symptoms (r = −.343, p<.05, FDR correction). Within each state we also examined connectivity within and between established intrinsic connectivity networks, and found that UFDR were similar to the OCD group in State I, but more similar to the HC groups in State II. The similarities between OCD and UFDR groups in temporal properties and State I connectivity indicate that these features may reflect the endophenotype for OCD. These results indicate that the temporal dynamics of functional connectivity could be a useful biomarker to identify those at risk.

Altered white matter structural networks in drug-naïve patients with obsessive-compulsive disorder

White matter (WM) alteration is considered to be a vital neurological mechanism of obsessive-compulsive disorder (OCD). However, little is known regarding the changes in topological organization of WM structural network in OCD. We acquired diffusion tensor imaging (DTI) datasets from 28 drug-naïve OCD patients and 28 well-matched healthy controls (HC). A deterministic fiber tracking approach was used to construct the whole-brain structural connectome. Group differences in global and nodal topological properties as well as rich-club organizations were compared by using graph theory analysis. The relationship between the altered network metrics and the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) was calculated. Compared with controls, OCD patients exhibited a significantly decreased small-worldness (σ), normalized clustering coefficient (γ) and shortest path length (L_p), as well as an increased global efficiency (E_glob). The nodal efficiency (E_nodal) was found to be reduced in the left middle frontal gyrus, and increased in the right parahippocampal gyrus and bilateral putamen in OCD patients. Besides, OCD patients showed increased rich-club, feeder and local connection strength, and the connection strength of the rich-club was positively correlated with the total Y-BOCS score. Our findings emphasized a central role for the complicatedly changed topological architecture of brain structural networks in the pathological mechanism underlying OCD.

Cellular and Extracellular White Matter Abnormalities in Obsessive-Compulsive Disorder: A Diffusion Magnetic Resonance Imaging Study

BACKGROUND

While previous studies have implicated white matter (WM) as a core pathology of obsessive-compulsive disorder (OCD), the underlying neurobiological processes remain elusive. This study used free-water (FW) imaging derived from diffusion magnetic resonance imaging to identify cellular and extracellular WM abnormalities in patients with OCD compared with control subjects. Next, we investigated the association between diffusion measures and clinical variables in patients.

METHODS

We collected diffusion-weighted magnetic resonance imaging and clinical data from 83 patients with OCD (56 women/27 men, age 37.7 ± 10.6 years) and 52 control subjects (27 women/25 men, age 32.8 ± 11.5 years). Fractional anisotropy (FA), FA of cellular tissue, and extracellular FW maps were extracted and compared between patients and control subjects using tract-based spatial statistics and voxelwise comparison in FSL Randomise. Next, we correlated these WM measures with clinical variables (age of onset and symptom severity) and compared them between patients with and without comorbidities and patients with and without psychiatric medication.

RESULTS

Patients with OCD demonstrated lower FA (43.4% of the WM skeleton), lower FA of cellular tissue (31% of the WM skeleton), and higher FW (22.5% of the WM skeleton) compared with control subjects. We did not observe significant correlations between diffusion measures and clinical variables. Comorbidities and medication status did not influence diffusion measures.

CONCLUSIONS

Our findings of widespread FA, FA of cellular tissue, and FW abnormalities suggest that OCD is associated with microstructural cellular and extracellular abnormalities beyond the corticostriatothalamocortical circuits. Future multimodal longitudinal studies are needed to understand better the influence of essential clinical variables across the illness trajectory.

White Matter Alterations of the Goal-Directed System in Patients With Obsessive-Compulsive Disorder and Their Unaffected First-Degree Relatives

BACKGROUND

It has been postulated that the neurobiological mechanism responsible for the onset of symptoms of obsessive-compulsive disorder (OCD), especially compulsive behavior, is related to alterations of the goal-directed and habitual learning systems. However, little is known about whether changes in these learning systems co-occur with changes in the white matter structure of patients with OCD and their unaffected first-degree relatives (UFDRs).

METHODS

Diffusion tensor imaging data were acquired from 32 patients with OCD (21 male), 32 UFDRs (16 male), and 32 healthy control subjects (16 male). White matter tracts in the goal-directed and habitual networks were reconstructed with seed-based probabilistic tractography. Partial least squares path modeling was used to measure the covariation between white matter connectivity, psychiatric symptoms, and cognitive flexibility.

RESULTS

Patients with OCD showed reduced connectivity in the fiber tracts within the goal-directed but not within the habitual network compared with healthy control subjects. Using partial least squares path modeling, patients' symptoms were negatively associated with connectivity within the goal-directed but not within the habitual network. Cognitive flexibility was correlated negatively with caudate-dorsolateral prefrontal cortex tracts in patients with OCD. UFDRs also exhibited reduced white matter connectivity in the goal-directed network.

CONCLUSIONS

These findings suggest that the balance of learning systems in OCD may be disrupted, mainly impairing white matter in the goal-directed network. Alterations of the goal-directed network could explain overt symptoms and impaired cognitive flexibility in patients with OCD. Similar alterations in the goal-directed network are present in UFDRs. The impaired goal-directed system may be an endophenotype of OCD.

White matter microstructural and Compulsive Sexual Behaviors Disorder - Diffusion Tensor Imaging study

BACKGROUND AND AIMS

Even though the Compulsive Sexual Behavior Disorder (CSBD) was added to the ICD-11 under the impulse control category in 2019, its neural mechanisms are still debated. Researchers have noted its similarity both to addiction and to Obssesive-Compulsive Disorder (OCD). The aim of our study was to address this question by investigating the pattern of anatomical brain abnormalities among CSBD patients.

METHODS

Reviewing 39 publications on Diffusion Tensor Imaging (DTI) we have identified main abnormalities specific for addictions and OCD. Than we have collected DTI data from 36 heterosexual males diagnosed with CSBD and 31 matched healthy controls. These results were then compared to the addiction and OCD patterns.

RESULTS

Compared to controls, CSBD individuals showed significant fractional anisotropy (FA) reduction in the superior corona radiata tract, the internal capsule tract, cerebellar tracts and occipital gyrus white matter. Interestingly, all these regions were also identified in previous studies as shared DTI correlates in both OCD and addiction.

DISCUSSION AND CONCLUSIONS

Results of our study suggest that CSBD shares similar pattern of abnormalities with both OCD and addiction. As one of the first DTI study comparing structural brain differences between CSBD, addictions and OCD, although it reveals new aspects of CSBD, it is insufficient to determine whether CSBD resembles more an addiction or OCD. Further research, especially comparing directly individuals with all three disorders may provide more conclusive results.

An association of Myelin Oligodendrocyte Glycoprotein (MOG) gene variants with white matter volume in pediatric obsessive-compulsive disorder

An increasing number of neuroimaging studies have implicated alterations of white matter in obsessive-compulsive disorder (OCD). The myelin oligodendrocyte glycoprotein (MOG) gene plays a major role in myelination, and has previously demonstrated significant association with this disorder, thus variations in this gene may contribute to observed white matter alterations. The purpose of this study is to examine the relationship between white matter volume in OCD and genetic variations in the MOG gene. Two polymorphisms in the MOG gene, MOG(C1334T) and MOG(C10991T), were investigated for association with total white matter volume as measured using volumetric magnetic resonance imaging in 37 pediatric OCD patients. We compared white matter volumes between allele and genotype groups for each polymorphism using ANCOVA. A significant relationship was detected between genotype C/C of MOG(C10991T) and decreased total white matter volume (P = 0.016). Our results showed an association between a MOG genetic variant and white matter volume. This finding is intriguing in light of the posited role of white matter alteration in the etiology of at least some cases of childhood-onset OCD. Further investigation with larger samples and sub-regional white matter volume phenotypes is warranted.

Meta-Analysis of white matter diffusion tensor imaging alterations in borderline personality disorder

Borderline personality disorder (BorPD) is characterized by instability and mood dysregulation, unstable relationships and distorted self-image. Identification of underlying anatomical and physiological changes is crucial to refine current treatments and develop new ones. In this perspective, previous magnetic resonance imaging studies have highlighted alterations associated with BorPD phenotype. In particular, diffusion-weighted imaging/Diffusion tensor imaging (DWI/DTI) has identified many white matter structural alterations in individuals with this diagnosis. Although in its infancy, limiting this line of investigation is a lack of direction at the field level. Hence, the present paper aims to conduct a meta-analysis of DWI/DTI findings in individuals with a diagnosis of BorPD, testing the hypothesis that there are specific white matter alterations associated with BorPD. To this end, we performed a meta-analysis of the existing literature of DWI/DTI in BorPD representing a total of 123 individuals with BorPD and 117 Controls. Our results indicated that individuals with BorPD show regions of reduced fractional anisotropy in the corpus callosum and fornix. These results survived all jack-knife reshuffles and showed no publication bias. This suggests that alterations in these structures may contribute to psychopathology. Further, the present results lend support to extant psychological and biological models of BorPD.

White matter microstructure and connectivity in patients with obsessive-compulsive disorder and their unaffected siblings

OBJECTIVE

We aimed to examine white matter microstructure and connectivity in individuals with obsessive-compulsive disorder (OCD) and their unaffected siblings, relative to healthy controls.

METHODS

Diffusion-weighted magnetic resonance imaging (dMRI) scans were acquired in 30 patients with OCD, 21 unaffected siblings, and 31 controls. We examined white matter microstructure using measures of fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD). Structural networks were examined using network-based statistic (NBS).

RESULTS

Compared to controls, OCD patients showed significantly reduced FA and increased RD in clusters traversing the left forceps minor, inferior fronto-occipital fasciculus, anterior thalamic radiation, and cingulum. Furthermore, the OCD group displayed significantly weaker connectivity (quantified by the streamline count) compared to controls in the right hemisphere, most notably in edges connecting subcortical structures to temporo-occipital cortical regions. The sibling group showed intermediate streamline counts, FA and RD values between OCD and healthy control groups in connections found to be abnormal in patients with OCD. However, these reductions did not significantly differ compared to controls.

CONCLUSION

Therefore, siblings of OCD patients display intermediate levels in dMRI measures of microstructure and connectivity, suggesting white matter abnormalities might be related to the familial predisposition for OCD.

Microstructural white matter abnormalities in obsessive-compulsive disorder: A coordinate-based meta-analysis of diffusion tensor imaging studies

BACKGROUND

There are no conclusive diffusion tensor imaging (DTI) findings on obsessive-compulsive disorder (OCD) for now. We conducted a comprehensive meta-analysis of DTI studies to identify white matter (WM) microarchitecture changes in OCD, and also to compare the results differences between the two most frequently used methods (voxel-based analysis, VBA versus tract-based spatial statistics, TBSS) for DTI data.

METHODS

A systematic search was performed on relevant studies that reported fractional anisotropy (FA) alterations between patients with OCD and healthy controls (HC). Seed-based d mapping (SDM) was applied to analyze microstructural WM abnormalities in OCD patients. Subgroup meta-analysis was subsequently performed to explore methodological differences between VBA and TBSS approaches.

RESULTS

A total of 30 studies (with 31 datasets) that comprised 855 patients and 875 HC were identified. OCD patients exhibited significantly decreased FA in the right cerebellar hemispheric lobule, corpus callosum (CC), left superior frontal gyrus (orbital part), right gyrus rectus, left superior longitudinal fasciculus and right lenticular nucleus in the pooled meta-analysis. The VBA subgroup showed lower FA in several brain regions while the TBSS subgroup only exhibited significant FA reductions in the CC.

CONCLUSION

According to the pooled meta-analysis, OCD patients presented microstructural abnormalities in distributed WM tracts. However, heterogeneous results were found between VBA and TBSS studies.

Diffusion Tensor Imaging Before and 3 Months After Concentrated Exposure Response Prevention in Obsessive-Compulsive Disorder

Background: Subtle differences in white matter microstructure have been found in obsessive-compulsive disorder (OCD) compared to controls using diffusion tensor imaging (DTI), but it is unclear if and how this change after treatment. The primary aim of this pre-registered study was to investigate white matter integrity between OCD patients and controls and changes after concentrated exposure and response prevention (ERP). Methods: Fractional anisotropy (FA), radial diffusivity (RD), axial diffusivity (AD) and mean diffusivity (MD) were estimated using FMRIB Software Library (FSL). The images were registered to a study-specific template using a longitudinal pipeline based on full tensor information in DTI-TK. Voxel-based analysis was performed using tract-based spatial statistics (TBSS). Using SPSS, we compared the integrity in three bilateral regions of interest (ROI), the sagittal stratum, posterior thalamic radiation and cingulum, in 32 OCD patients and 30 matched healthy controls at baseline. Patients received a four-day concentrated ERP format. We investigated longitudinal changes in 26 OCD patients and 22 healthy controls at 3months follow-up using repeated-measures ANOVA. Exploratory t-tests were conducted for AD and MD. Secondary hypothesis used linear regression to investigate if baseline FA predict treatment outcome 3 months later, and if patients with illness onset before 18 years of age would show lower FA in sagittal stratum. Finally, we performed sensitivity analysis on medication and comorbidity influences on FA. Results: Three months after treatment, 77% of the patients were in remission. Contrary to our hypotheses, we did not find any significant differences in FA, RD, AD or MD between the groups before treatment, nor significant group by time effects in any of the ROI. None of the baseline FA measures significantly predicted treatment outcome. Illness onset before 18 years of age did not significantly predict FA in the sagittal stratum. Adjusting for medication or comorbid anxiety or mood disorder did not influence the results. Conclusions: Although concentrated ERP in OCD lead to high remission, we did not find significant long-term changes by DTI. Future studies will benefit from using larger sample sizes and multi-shell diffusion-weighted imaging when investigating white matter microstructure in OCD and underlying neurobiological mechanisms of treatment.

Neural correlates of symptom severity in obsessive-compulsive disorder using magnetization transfer and diffusion tensor imaging

Recent neuroimaging studies in OCD have reported structural alterations in the brain, not limited to frontostriatal regions. While Diffusion Tensor Imaging (DTI) is typically used to interrogate WM microstructure in OCD, additional imaging metric, such as Magnetization Transfer Imaging (MTI), allows for further identification of subtle but important structural changes across both GM and WM. In this study, both MTI and DTI were utilised to investigate the structural integrity of the brain, in OCD in relation to healthy controls. 38 adult OCD patients were recruited, along with 41 age- and gender-matched controls. Structural T1, MTI and DTI data were collected. Case-control differences in Magnetization Transfer Ratio (MTR) and DTI metrics (FA, MD) were examined, along with MTR/DTI-related associations with symptom severity in patients. No significant group differences were found across MTR, FA, and MD. However, OCD symptom severity was positively correlated with MTR in a distributed network of brain regions, including the striatum, cingulate, orbitofrontal area and insula. Within the same regions, OCD symptoms were also positively correlated with FA in WM, and negatively correlated with MD in GM. These results indicate a greater degree of myelination in certain cortical and subcortical regions in the more severe cases of OCD.

Toward identifying reproducible brain signatures of obsessive-compulsive profiles: rationale and methods for a new global initiative

BACKGROUND

Obsessive-compulsive disorder (OCD) has a lifetime prevalence of 2-3% and is a leading cause of global disability. Brain circuit abnormalities in individuals with OCD have been identified, but important knowledge gaps remain. The goal of the new global initiative described in this paper is to identify robust and reproducible brain signatures of measurable behaviors and clinical symptoms that are common in individuals with OCD. A global approach was chosen to accelerate discovery, to increase rigor and transparency, and to ensure generalizability of results.

METHODS

We will study 250 medication-free adults with OCD, 100 unaffected adult siblings of individuals with OCD, and 250 healthy control subjects at five expert research sites across five countries (Brazil, India, Netherlands, South Africa, and the U.S.). All participants will receive clinical evaluation, neurocognitive assessment, and magnetic resonance imaging (MRI). The imaging will examine multiple brain circuits hypothesized to underlie OCD behaviors, focusing on morphometry (T1-weighted MRI), structural connectivity (Diffusion Tensor Imaging), and functional connectivity (resting-state fMRI). In addition to analyzing each imaging modality separately, we will also use multi-modal fusion with machine learning statistical methods in an attempt to derive imaging signatures that distinguish individuals with OCD from unaffected siblings and healthy controls (Aim #1). Then we will examine how these imaging signatures link to behavioral performance on neurocognitive tasks that probe these same circuits as well as to clinical profiles (Aim #2). Finally, we will explore how specific environmental features (childhood trauma, socioeconomic status, and religiosity) moderate these brain-behavior associations.

DISCUSSION

Using harmonized methods for data collection and analysis, we will conduct the largest neurocognitive and multimodal-imaging study in medication-free subjects with OCD to date. By recruiting a large, ethno-culturally diverse sample, we will test whether there are robust biosignatures of core OCD features that transcend countries and cultures. If so, future studies can use these brain signatures to reveal trans-diagnostic disease dimensions, chart when these signatures arise during development, and identify treatments that target these circuit abnormalities directly. The long-term goal of this research is to change not only how we conceptualize OCD but also how we diagnose and treat it.

White matter microstructural alterations across four major psychiatric disorders: mega-analysis study in 2937 individuals

Identifying both the commonalities and differences in brain structures among psychiatric disorders is important for understanding the pathophysiology. Recently, the ENIGMA-Schizophrenia DTI Working Group performed a large-scale meta-analysis and reported widespread white matter microstructural alterations in schizophrenia; however, no similar cross-disorder study has been carried out to date. Here, we conducted mega-analyses comparing white matter microstructural differences between healthy comparison subjects (HCS; N = 1506) and patients with schizophrenia (N = 696), bipolar disorder (N = 211), autism spectrum disorder (N = 126), or major depressive disorder (N = 398; total N = 2937 from 12 sites). In comparison with HCS, we found that schizophrenia, bipolar disorder, and autism spectrum disorder share similar white matter microstructural differences in the body of the corpus callosum; schizophrenia and bipolar disorder featured comparable changes in the limbic system, such as the fornix and cingulum. By comparison, alterations in tracts connecting neocortical areas, such as the uncinate fasciculus, were observed only in schizophrenia. No significant difference was found in major depressive disorder. In a direct comparison between schizophrenia and bipolar disorder, there were no significant differences. Significant differences between schizophrenia/bipolar disorder and major depressive disorder were found in the limbic system, which were similar to the differences in schizophrenia and bipolar disorder relative to HCS. While schizophrenia and bipolar disorder may have similar pathological characteristics, the biological characteristics of major depressive disorder may be close to those of HCS. Our findings provide insights into nosology and encourage further investigations of shared and unique pathophysiology of psychiatric disorders.

Abnormal Regional Homogeneity in Patients With Obsessive-Compulsive Disorder and Their Unaffected Siblings: A Resting-State fMRI Study

Objective: Previous studies suggest that abnormal brain structure and function may be neuroimaging endophenotypes of obsessive-compulsive disorder (OCD). Comparing the intrinsic brain activity of OCD patients and their unaffected siblings will help to further understand the susceptibility to, and pathological mechanisms of, OCD. We used a case-control study design aiming to establish whether the abnormal regional homogeneity (ReHo) found in OCD patients also exists in their unaffected siblings. Method: Fifteen unmedicated OCD patients, 15 of their unaffected siblings, and 30 healthy controls (HCs) received resting-state functional magnetic resonance imaging (r-s fMRI) scanning and clinical evaluation. We used the ReHo method to analyze the inter-regional synchronized activity of all participants. One-way analysis of covariance with post hoc tests was used to compare the ReHo maps across groups. A Pearson correlation analysis was conducted to assess the correlations between clinical characteristics and abnormal ReHo in OCD patients. Results: Relative to HCs, OCD patients and their unaffected siblings showed overlapping higher ReHo values in the right dorsolateral prefrontal cortex (DLPFC). Patients with OCD showed increased ReHo in left middle frontal gyrus (MFG) relative to both their unaffected siblings and HCs. In addition to the right DLPFC and left MFG, OCD patients, compared with HCs, also showed abnormal ReHo in other regions, including higher ReHo in the right superior parietal cortex and lower ReHo in the left inferior parietal cortex, right parahippocampal region, left thalamus, and right inferior temporal cortex. Compared with HCs, the unaffected siblings of patients with OCD had significantly higher ReHo in the right inferior parietal cortex, right MFG, and right supplementary motor area. There was no association between clinical symptoms and abnormal ReHo values in OCD patients. Conclusions: This study found overlapping higher ReHo values in the right DLPFC of OCD patients and their unaffected siblings. Our results suggest that the higher ReHo in the right DLPFC may be a potential neuroimaging endophenotype, which may reflect an increased genetic risk of OCD.

Serum Proteomic Study of Women With Obsessive-Compulsive Disorder, Washing Subtype

Introduction

Many genetic studies are conducted on Obsessive-Compulsive Disorder (OCD). however, a high-throughput examination of proteome profile of this severe disease has not been performed yet.

Methods

Here, the proteomic study of OCD patients' serum samples was conducted by the application of Two-Dimensional Electrophoresis (2DE) followed by Mass Spectrometry (MALDI-TOF-TOF).

Results

A total of 240 protein spots were detected and among them, five significant differentially expressed protein spots with the fold change of ≥1.5 were considered for further evaluations. These proteins include IGKC, GC, HPX, and two isoforms of HP. While IGKC and HP show down-regulation, GC and HPX indicate up-regulation. Moreover, a validation study of overall HP levels in patients' serum via nephelometric quantification confirmed the lower levels of this protein in the serum of OCD patients. Additionally, enrichment analysis and validation test revealed that inflammation is one of most dominant processes in OCD.

Conclusion

It is suggested that these candidate proteins and their underlying processes (especially, inflammation) may be linked to OCD pathophysiology and can promise a clinical use after extensive validation studies.

The cingulum bundle: Anatomy, function, and dysfunction

The cingulum bundle is a prominent white matter tract that interconnects frontal, parietal, and medial temporal sites, while also linking subcortical nuclei to the cingulate gyrus. Despite its apparent continuity, the cingulum's composition continually changes as fibres join and leave the bundle. To help understand its complex structure, this review begins with detailed, comparative descriptions of the multiple connections comprising the cingulum bundle. Next, the impact of cingulum bundle damage in rats, monkeys, and humans is analysed. Despite causing extensive anatomical disconnections, cingulum bundle lesions typically produce only mild deficits, highlighting the importance of parallel pathways and the distributed nature of its various functions. Meanwhile, non-invasive imaging implicates the cingulum bundle in executive control, emotion, pain (dorsal cingulum), and episodic memory (parahippocampal cingulum), while clinical studies reveal cingulum abnormalities in numerous conditions, including schizophrenia, depression, post-traumatic stress disorder, obsessive compulsive disorder, autism spectrum disorder, Mild Cognitive Impairment, and Alzheimer's disease. Understanding the seemingly diverse contributions of the cingulum will require better ways of isolating pathways within this highly complex tract.

The detection of white matter alterations in obsessive-compulsive disorder revealed by TRActs Constrained by UnderLying Anatomy (TRACULA)

PURPOSE

In recent years, a large number of studies have investigated obsessive-compulsive disorder (OCD) using diffusion-weighted images (DWIs) and have reported microstructural abnormalities in various regions, mainly the corpus callosum and cingulum. In the present study, we aimed to detect microstructural changes in the white matter using whole-brain tractography.

PATIENTS AND METHODS

We obtained MRI data from 25 adult non-medicated OCD patients and 27 healthy controls. DWI data from MRI scans were analyzed by the automated probabilistic tractography method referred to as TRActs Constrained by UnderLying Anatomy (TRACULA). We investigated diffusivity parameters: fractional anisotropy, radial diffusivity (RD), axial diffusivity, and mean diffusivity in 18 major white matter tracts and examined indices to know which measurements in which fibers can predict the diagnosis of OCD.

RESULTS

Compared to healthy controls, OCD patients had significantly increased RD in the forceps major and a reduction of RD in the right cingulum angular (infracallosal) bundle. There was no correlation between these values and the clinical features.

CONCLUSION

We found RD alterations in the forceps major and the right cingulum angular (infracallosal) bundle, which might be associated with myelination changes in the temporal and occipital regions in OCD. Our results suggest that the pathogenesis of OCD may include abonormality of myelination status in not only the fronto-striato-thalamic circuit but also the posterior and temporal regions.

Altered frontal interhemispheric and fronto-limbic structural connectivity in unmedicated adults with obsessive-compulsive disorder

BACKGROUND

Previous diffusion tensor imaging (DTI) studies of obsessive-compulsive disorder (OCD) have primarily used voxel- or tract-based methods to assess white matter microstructure in medicated patients. This is the first probabilistic tractography study to assess the structural connectivity of all major white matter tracts in unmedicated adults with OCD without comorbid psychopathology. We hypothesized that OCD compared to healthy participants would show reduced integrity in frontal interhemispheric and fronto-limbic tracts.

METHODS

DTI data from 29 unmedicated adults with OCD were compared to that of 27 matched healthy control (HC) participants. TRACULA was used to assess probabilistic tractography and compare groups in the average fractional anisotropy (FA) of 8 bilateral tracts plus forceps minor and major, and explore group differences in axial (AD), radial (RD), and mean (MD) diffusivities in tracts where FA differed across groups.

RESULTS

Significantly less FA was detected in OCD compared to HC participants in forceps minor, interhemispheric fibers of the frontal cortex, and right uncinate fasciculus (UNC), association fibers connecting frontal and limbic regions (p's < .05). FA in forceps minor was inversely associated with symptom severity in the OCD participants. Exploratory analyses revealed less AD in right UNC was inversely associated with OCD symptoms.

CONCLUSIONS

Structural connectivity of frontal interhemispheric and fronto-limbic circuits may be altered in unmedicated adults with OCD, especially those with the most severe symptoms. These findings suggest a microstructural basis for the abnormal function and reduced resting-state connectivity of frontal regions and fronto-limbic circuits in OCD.

Abnormal white matter structural connectivity in adults with obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a complex and severe psychiatric disorder whose pathogenesis is not fully understood. Recent studies have shown white matter (WM) alterations in adults with OCD, but the results have been inconsistent. The present study investigated WM structure in OCD patients with the hypothesis that large-scale brain networks may be disrupted in OCD. A total of 24 patients with OCD and 23 healthy controls (HCs) were scanned with diffusion tensor imaging. A tract-based spatial statistics (TBSS) approach was used to detect differences across the whole brain in patients with OCD vs HCs; post hoc fiber tractography was applied to characterize developmental differences between the two groups. Relative to HCs, patients with OCD had lower fractional anisotropy (FA) values in the corpus callosum (CC), left anterior corona radiata (ACR), left superior corona radiata (SCR) and left superior longitudinal fasciculus (SLF), and higher radial diffusivity in the genu and body of CC. Among the TBSS de-projected region of interest results, compared with HCs, patients with OCD showed lower of the mean FA values of fiber bundles passing though the SLF, and shorter lengths of ACR, SCR and CC. In conclusion, this study provides novel evidence of widespread microstructural alterations in OCD and suggests that OCD may involve abnormalities affecting a broader network of regions than commonly believed.

Microstructural changes of brain in patients with aromatic L-amino acid decarboxylase deficiency

Aromatic L-amino acid decarboxylase (AADC) deficiency is an uncommon inherited neurometabolic disease. The clinical presentations and MR findings in children with AADC deficiency were investigated. Total 12 children (6 boys, 6 girls), aged from 9 to 50 months (mean, 23 ±13 months), with AADC deficiency, were enrolled for analysis. Of 12 patients enrolled, clinical presentations included global developmental delay with generalized hypotonia in 12 (100%), dystonia in 12 (100%), oculogyric crisis in 12 (100%), and excessive sweating in 8 (67%). Sleep problem was also found in 4 (33%). Of 15 MR examinations, the major changes included 6 (40%) with diffusely prominent bilateral frontal sulci, 10 (67%) with prominent frontal horns, and 12 (80%) with hypomyelination. In AADC patients, the frontal horn was significantly widened (P < 0.01), and the volume of caudate nucleus was also significantly smaller than that of controls (P = 0.02). The ratios of thickness of the splenium to that of the genu of corpus callosum were also significantly increased (P < 0.01). There was also significant decrease of fiber density indices in major white matter fiber tracts. Using Tract-Based Spatial Statistics approach, we also revealed significant change in major fiber tracts related to language function and motor function. In conclusion, the present study indicated that AADC deficiency may have significant impact on brain development, especially the frontal lobe and fiber tracts related to language function and motor function. Long-term follow-up of brain MRI in patients with AADC deficiency may clarify the possible effect of AADC deficiency on brain development. Hum Brain Mapp 38:1532-1540, 2017. © 2016 Wiley Periodicals, Inc.

Can Neuroimaging Provide Reliable Biomarkers for Obsessive-Compulsive Disorder? A Narrative Review

In this integrative review, we discuss findings supporting the use neuroimaging biomarkers in the diagnosis and treatment of obsessive-compulsive disorder (OCD). To do so, we have selected the most recent studies that attempted to identify the underlying pathogenic process associated with OCD and whether they provide useful information to predict clinical features, natural history or treatment responses. Studies using functional magnetic resonance (fMRI), voxel-based morphometry (VBM), diffusion tensor imaging (DTI) and proton magnetic resonance spectroscopy (1H MRS) in OCD patients are generally supportive of an expanded version of the earlier cortico-striatal-thalamus-cortical (CSTC) model of OCD. Although it is still unclear whether this information will be incorporated into the daily clinical practice (due to current conceptual approaches to mental illness), statistical techniques, such as pattern recognition methods, appear promising in identifying OCD patients and predicting their outcomes.

Shared white matter alterations across emotional disorders: A voxel-based meta-analysis of fractional anisotropy

Background

White matter (WM) integrity may represent a shared biomarker for emotional disorders (ED). Aims: To identify transdiagnostic biomarkers of reduced WM by meta-analysis of findings across multiple EDs.

Method

Web of Science was searched systematically for studies of whole brain analysis of fractional anisotropy (FA) in adults with major depressive disorder, bipolar disorder, social anxiety disorder, obsessive-compulsive disorder or posttraumatic stress disorder compared with a healthy control (HC) group. Peak MNI coordinates were extracted from 37 studies of voxel-based analysis (892 HC and 962 with ED) and meta-analyzed using seed-based d Mapping (SDM) Version 4.31. Separate meta-analyses were also conducted for each disorder.

Results

In the transdiagnostic meta-analysis, reduced FA was identified in ED studies compared to HCs in the left inferior fronto-occipital fasciculus, forceps minor, uncinate fasciculus, anterior thalamic radiation, superior corona radiata, bilateral superior longitudinal fasciculi, and cerebellum. Disorder-specific meta-analyses revealed the OCD group had the most similarities in reduced FA to other EDs, with every cluster of reduced FA overlapping with at least one other diagnosis. The PTSD group was the most distinct, with no clusters of reduced FA overlapping with any other diagnosis. The BD group were the only disorder to show increased FA in any region, and showed a more bilateral pattern of WM changes, compared to the other groups which tended to demonstrate a left lateralized pattern of FA reductions.

Conclusions

Distinct diagnostic categories of ED show commonalities in WM tracts with reduced FA when compared to HC, which links brain networks involved in cognitive and affective processing. This meta-analysis facilitates an increased understanding of the biological markers that are shared by these ED.

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A meta-analysis of FA in MDD, bipolar, social anxiety disorder, OCD and PTSD

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Reduced FA in left superior longitudinal and inferior fronto-occipital fasciculi

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Distinct diagnostic categories show commonalities of white matter changes.

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Differences among diagnostic categories also found, PTSD most distinct

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White matter integrity may be a shared biomarker for emotional disorders.