The bifocal model: A two-level clinical model of psychiatric disorders integrating diagnostic and transdiagnostic approaches.

Nowadays, two distinct conceptualizations are available to classify, label and guide the treatment of psychiatric disorders: the diagnostic approach and the transdiagnostic approach. There are pros and cons to both approaches. We propose here to link these two conceptualizations by creating a two-level clinical model that takes advantages of both approaches, named the bifocal model (BFM). This two-tier clinical model consists of a double level of analysis: the first step is to identify transdiagnostic mechanisms involved in multiple disorders and then to recognize specific mechanisms identified in a given disorder or cluster of symptoms. Such a process would bring the diagnostic and transdiagnostic approaches together and offer a more flexible way to understand mental disorders and ultimately to improve medical outcomes.