Biomarkers of Obsessive-Compulsive Disorder Subtypes: A Literature Review.

Obsessive-compulsive disorder (OCD) is a heterogeneous mental illness characterized by a variety of clinical manifestations and underlying neurobiological mechanisms. Modern research highlights the importance of identifying subtypes of OCD-separate categories that are characterized by specific phenotypic manifestations. This review provides a systematic integration of multi-level biomarker data (genetic, neuroimaging, neuropsychological) specifically aligned with the most consistently replicated, symptom-based subtypes of OCD. Our findings demonstrate that distinct OCD subtypes are underpinned by divergent neurobiological pathways, involving dysregulation across glutamatergic, serotonergic, dopaminergic, and neurotrophic systems, as well as distinct patterns of brain region engagement. The most extensive body of evidence currently exists for the contamination/cleaning and symmetry/ordering OCD subtypes. In contrast, other subtypes require more rigorous investigation. The findings from this study can provide theoretical prerequisites for future experimental studies involving larger cohorts of OCD patients, who can then be classified based on their detected biomarkers and tested accordingly.