Comorbidity of obsessive–compulsive disorder and substance use disorder: a new heuristic

Obsessive-compulsive disorder (OCD) and substance use disorder share several aspects of phenomenology and may be underpinned by a common mechanism with compulsivity at the core. Despite this overlap, the two disorders show a variable pattern of comorbidity. Here, we review the current evidence for comorbidity across clinical and epidemiological studies, and propose a new heuristic for substance use comorbidity in OCD, based on a hypothetical threshold of OCD severity.