Obsessive-compulsive disorder (OCD) may be particularly amenable to this approach since it represents one of the better investigated neurocircuit-based models [11]. OCD has traditionally been associated with dysfunctional cortico-striatal-thalamo-cortical (CSTC) circuits [12–13], although it is now recognized that alterations in other circuits (fronto-limbic, fronto-parietal, cerebellar) also play a role [14]. Abnormalities in these different neurocircuits likely interact with each other to generate the complex OCD phenotype [13–14]. Therefore, individuals with OCD may have different degrees and patterns of alterations in these neurocircuits, leading to the phenotypic heterogeneity. Finally, there are already several initiatives identifying trans-diagnostic aspects of the clinical phenomenology of obsessive-compulsive symptoms based on their association with broader concepts, such as compulsivity and anxiety [14–16].
