Cortical Abnormalities Associated With Pediatric and Adult Obsessive-Compulsive Disorder: Findings From the ENIGMA Obsessive-Compulsive Disorder Working Group

Mapping Alterations of the Functional Structure of the Cerebral Cortex in Obsessive–Compulsive Disorder

We mapped alterations of the functional structure of the cerebral cortex using a novel imaging approach in a sample of 160 obsessive–compulsive disorder (OCD) patients. Whole-brain functional connectivity maps were generated using multidistance measures of intracortical neural activity coupling defined within isodistant local areas. OCD patients demonstrated neural activity desynchronization within the orbitofrontal cortex and in primary somatosensory, auditory, visual, gustatory, and olfactory areas. Symptom severity was significantly associated with the degree of functional structure alteration in OCD-relevant brain regions. By means of a novel imaging perspective, we once again identified brain alterations in the orbitofrontal cortex, involving areas purportedly implicated in the pathophysiology of OCD. However, our results also indicated that weaker intracortical activity coupling is also present in each primary sensory area. On the basis of previous neurophysiological studies, such cortical activity desynchronization may best be interpreted as reflecting deficient inhibitory neuron activity and altered sensory filtering.

Structural neuroimaging correlates of social deficits are similar in autism spectrum disorder and attention-deficit/hyperactivity disorder: analysis from the POND Network

Autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and obsessive-compulsive disorder (OCD) have been associated with difficulties recognizing and responding to social cues. Neuroimaging studies have begun to map the social brain; however, the specific neural substrates contributing to social deficits in neurodevelopmental disorders remain unclear. Three hundred and twelve children underwent structural magnetic resonance imaging of the brain (controls = 32, OCD = 44, ADHD = 77, ASD = 159; mean age = 11). Their social deficits were quantified on the Social Communication Questionnaire (SCQ) and the Reading the Mind in the Eyes Test (RMET). Multivariable regression models were used to examine the structural neuroimaging correlates of social deficits, with both a region of interest and a whole-brain vertex-wise approach. For the region of interest analysis, social brain regions were grouped into three networks: (1) lateral mentalization (e.g., temporal-parietal junction), (2) frontal cognitive (e.g., orbitofrontal cortex), and (3) subcortical affective (e.g., limbic system) regions. Overall, social communication deficits on the SCQ were associated with thinner cortices in the left lateral regions and the right insula, and decreased volume in the ventral striatum, across diagnostic groups (p = 0.006 to <0.0001). Smaller subcortical volumes were associated with more severe social deficits on the SCQ in ASD and ADHD, and less severe deficits in OCD. On the RMET, larger amygdala/hippocampal volumes were associated with fewer deficits across groups. Overall, patterns of associations were similar in ASD and ADHD, supporting a common underlying biology and the blurring of the diagnostic boundaries between these disorders.

An Empirical Comparison of Meta- and Mega-Analysis With Data From the ENIGMA Obsessive-Compulsive Disorder Working Group

Objective: Brain imaging communities focusing on different diseases have increasingly started to collaborate and to pool data to perform well-powered meta- and mega-analyses. Some methodologists claim that a one-stage individual-participant data (IPD) mega-analysis can be superior to a two-stage aggregated data meta-analysis, since more detailed computations can be performed in a mega-analysis. Before definitive conclusions regarding the performance of either method can be drawn, it is necessary to critically evaluate the methodology of, and results obtained by, meta- and mega-analyses.

Methods: Here, we compare the inverse variance weighted random-effect meta-analysis model with a multiple linear regression mega-analysis model, as well as with a linear mixed-effects random-intercept mega-analysis model, using data from 38 cohorts including 3,665 participants of the ENIGMA-OCD consortium. We assessed the effect sizes and standard errors, and the fit of the models, to evaluate the performance of the different methods.

Results: The mega-analytical models showed lower standard errors and narrower confidence intervals than the meta-analysis. Similar standard errors and confidence intervals were found for the linear regression and linear mixed-effects random-intercept models. Moreover, the linear mixed-effects random-intercept models showed better fit indices compared to linear regression mega-analytical models.

Conclusions: Our findings indicate that results obtained by meta- and mega-analysis differ, in favor of the latter. In multi-center studies with a moderate amount of variation between cohorts, a linear mixed-effects random-intercept mega-analytical framework appears to be the better approach to investigate structural neuroimaging data.

A Clinical Staging Model for Obsessive-Compulsive Disorder: Is It Ready for Prime Time?

Recent changes to the diagnostic classification of obsessive-compulsive disorder (OCD), including its removal from the anxiety/neurotic, stress-related and somatoform disorders chapters of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) and International Classification of Diseases 11th Revision (ICD-11), are based on growing evidence of unique pathogenic signatures and linked diagnostic and treatment approaches. In this review, we build on these recent developments and propose a 'clinical staging model' of OCD that integrates the severity of symptoms and phase of illness for personalised case management. A clinical staging model is especially relevant for the early identification and management of subthreshold OCD - a substantial and largely neglected portion of the population who, despite having milder symptoms, experience harms that may impact personal relationships, work-related functioning and productivity. Research on the pathogenesis, classification and management of such cases is needed, including the development of new outcomes measures that prove sensitive to changes in future clinical trials. Early intervention strategies in OCD are likely to yield better long-term outcomes.

Obsessive-compulsive disorder and global mental health

The discipline of global mental health has emphasized the importance of the treatment gap in mental disorders, and of addressing this gap via changes in health policy, an emphasis on human rights, and innovations such as task-shifting. Although global mental health research has focused on both common mental disorders such as depression, and serious mental disorders such as schizophrenia, it has paid relatively little attention to obsessive-compulsive and related disorders (OCRDs). Nevertheless, international collaborations have recently paid a good deal of attention to the nosology and neurobiology of OCRDs, and given the prevalence and morbidity of these conditions, further work along these lines should be encouraged. This article provides a brief overview of recent international collaborations on OCRDs, and outlines future directions for such work.

Altered Cortico-Striatal Functional Connectivity During Resting State in Obsessive-Compulsive Disorder

Background: Neuroimaging studies show that obsessive-compulsive disorder (OCD) is characterized by an alteration of the cortico-striato-thalamo-cortical (CSTC) system in terms of an imbalance of activity between the direct and the indirect loop of the CSTC. As resting-state functional connectivity (FC) studies investigated only specific parts of the CSTC in patients with OCD up to now, the present study aimed at exploring FC in the CSTC as a whole. Methods: We investigated potential alterations in resting-state FC within the CSTC system in 44 OCD patients and 40 healthy controls by taking into consideration all relevant nodes of the direct and indirect CSTC loop. Results: Compared to healthy controls, OCD patients showed an increased FC between the left subthalamic nucleus (STN) and the left external globus pallidus (GPe), as well as an increased FC between the left GPe and the left internal globus pallidus (GPi). Conclusion: These findings may contribute to a better understanding of the OCD pathophysiology by providing further information on the connectivity alterations within specific regions of the CSTC system. In particular, increased FC between the STN and the left GPe may play a major role in OCD pathology. This assumption is consistent with the fact that these regions are also the main target sites of therapeutic deep brain stimulation in OCD.

Neuroimaging findings in obsessive-compulsive disorder: A narrative review to elucidate neurobiological underpinnings

Obsessive compulsive disorder (OCD) is a common psychiatric illness and significant research has been ongoing to understand its neurobiological basis. Neuroimaging studies right from the 1980s have revealed significant differences between OCD patients and healthy controls. Initial imaging findings showing hyperactivity in the prefrontal cortex (mainly orbitofrontal cortex), anterior cingulate cortex and caudate nucleus led to the postulation of the cortico-striato-thalamo-cortical (CSTC) model for the neurobiology of OCD. However, in the last two decades emerging evidence suggests the involvement of widespread associative networks, including regions of the parietal cortex, limbic areas (including amygdala) and cerebellum. This narrative review discusses findings from structural [Magnetic Resonance Imaging (MRI), Diffusion Tensor Imaging(DTI)], functional [(functional MRI (fMRI), Single photon emission computed tomography (SPECT), Positron emission tomography (PET), functional near-infrared spectroscopy (fNIRS)], combined structural and functional imaging studies and meta-analyses. Subsequently, we collate these findings to describe the neurobiology of OCD including CSTC circuit, limbic system, parietal cortex, cerebellum, default mode network and salience network. In future, neuroimaging may emerge as a valuable tool for personalised medicine in OCD treatment.

Symptom dimensions in obsessive-compulsive disorder as predictors of neurobiology and treatment response

Purpose of review

Specific symptom dimensions of obsessive-compulsive disorder (OCD) have been suggested as an approach to reduce the heterogeneity of obsessive-compulsive disorder, predict treatment outcome, and relate to brain structure and function. Here, we review studies addressing these issues.

Recent findings

The contamination and symmetry/ordering dimensions have not been reliably associated with treatment outcome. Some studies found that greater severity of sexual/aggressive/religious symptoms predicted a worse outcome after cognitive behavioral therapy (CBT) and a better outcome after serotonin reuptake inhibitors (SRIs). Contamination symptoms have been related to increased amygdala and insula activation in a few studies, while sexual/aggressive/religious symptoms have also been related to more pronounced alterations in the function and structure of the amygdala. Increased pre-treatment limbic responsiveness has been related to better outcomes of CBT, but most imaging studies show important limitations and replication in large-scale studies is needed. We review possible reasons for the strong limbic involvement of the amygdala in patients with more sexual/aggressive/religious symptoms, in relation to their sensitivity to CBT.

Summary

Symptom dimensions may predict treatment outcome, and patients with sexual/religious/aggressive symptoms are at a greater risk of not starting or delaying treatment. This is likely partly due to more shame and perceived immorality which is also related to stronger amygdala response. Competently delivered CBT is likely to help these patients improve to the same degree as patients with other symptoms.