Updating Apathy: Using Research Domain Criteria to Inform Clinical Assessment and Diagnosis of Disorders of Motivation.

Clinical observations regarding apathy and motivation derived from many psychiatric and neurological conditions have generated divergent descriptions of apathy-related syndromes. Stimulated by complex cases presenting with prominent apathy, uses of the term "apathy" and "related phenomena" in the Diagnostic and Statistical Manual of Mental Disorders, diagnostic proposals for apathy as a syndrome and disorder of motivation, Research Domain Criteria (RDoC) systems governing motivational processes, and their clinical intersections are reviewed. Clinical apathy and associated dysfunctions can be addressed using constructs suggested by the RDoC domain of Positive Valence Systems, including approach motivation and component processes of reward valuation, effort valuation/willingness to work, expectancy/reward prediction error, and responses to reward and reward learning. Although apathy syndromes have been validated, defining potentially distinct disorders of motivation (not simply subordinated to mood, psychotic, cognitive, or substance use disorders) will require additional research to better delineate etiology and pathogenesis, predictive validators, reliable diagnostic methods, treatments, and demonstrations of use for these diagnostic proposals.