Interestingly, frontal and anterior cingulate cortex, which were enriched in our tissue-based analyses, as well as hippocampus and striatum, which were implicated in our cell-type based analyses, are among the regions that are consistently implicated in neuroimaging studies of OCD41,71–73. Enrichment in MSNs in striatum is consistent with their role in the observed aberrant circuitry in OCD, where the medium spiny neurons D1 project to the globus pallidus interna and substantia nigra in the direct pathway, and the D2-type MSNs project to the globus pallidus externa in the indirect pathway74. However, medium spiny neurons are also enriched in major depressive disorder75, schizophrenia76, and intelligence77, suggesting that the observed enrichment is not specific for OCD.
