Towards an integration of psychological and biological models of obsessive-compulsive disorder: Phylogenetic considerations

In the past 10 to 15 years, advances in psychopharmacology and research on the neurobiological basis of obsessive-compulsive disorder (OCD) have led to the currently predominant biological model of OCD. Nevertheless, the centrality of complex ideation in OCD supports the usefulness of a psychological approach. In this article, we propose an integrated psychobiological model that presumes a biological etiology without assuming biological reductionism. We hypothesize that the relationship between biological and psychological organization is best explained in the context of emergent systems theory, and that the psychological meaning of OCD reflects development across phylogeny as opposed to ontogeny. Finally, we propose that OCD reflects disruption of a behavioral inhibition/harm assessment system that incorporates brain structures from different points across human phylogeny. Hence, complex psychological symptoms of a biological etiology are generated.