Gray Matter Morphological Alteration in Obsessive Compulsive Disorder: Evidence for an Inhibitory Control and Emotional Regulation Disorder

Abstract

The integration of obsessive compulsive disorders (OCD) in the Obsessive Compulsive and Related Disorders cluster, while emphasizing the centrality of inhibitory control and repetitive behaviors may fail to fully acknowledge the existence of significant affective and other cognitive impairments. The objective of this paper is to review evidence from gray matter morphology imaging studies identifying brain abnormalities in OCD that may help to explain the complexity of OCD impairments. Building on these studies, OCD seems to be a disorder of both inhibitory control and emotional regulation. Volumetric and shape abnormalities in different brain territories of the prefrontal cortex, orbitofrontal cortex, thalamus, striate and cerebellum may contribute to impairments in inhibitory control. On the other side, gray matter shape and volume alterations in regions such as the anterior cingulate, insula, amygdala and supramarginal gyrus may contribute to difficulties in emotional regulation. Beyond this inhibitory control – emotional regulation dichotomy, there are other psychological impairments that may be associated with gray matter alterations. For example, difficulties in memory monitoring may be sustained by shape and volumetric alterations in the dorso-lateral prefrontal cortex and the hippocampus. Additionally, visual-spatial impairments may be explained by gray matter shape and volume alterations in the superior parietal and occipital lobes as well as the precuneus. Overall the research confirms changes in volume and shape in multiple cortical and subcortical regions which can help to explain the complexity of OCD symptomatology and the diversity of OCD endophenotypes. Additionally, the evidence from brain shape anomalies may suggest the additional possibility of neurodevelopmental changes associated with the pathogenesis of OCD.