Recently, we performed meta- and mega-analyses on data from 3589 individuals and reported subcortical volume differences between OCD patients and healthy controls that were related to clinical characteristics. Distinct subcortical volume abnormalities were detected in adults and children with OCD. Adult OCD patients had significantly smaller hippocampal and larger pallidal volumes. The smaller hippocampal volume seemed to be driven by comorbid depression and an adult illness onset. The larger pallidal volume was more pronounced in adult OCD patients with a childhood illness onset. Children with OCD had larger thalamic volumes compared to control children (6).
