Anhedonia in depression: Mechanisms, assessment, and therapeutics

Anhedonia-defined behaviorally by persistently low motivation and inability to experience pleasure-is common to depressive disorders and portends worse long-term course. Although it has been recognized as a feature of chronic and recurrent depression since the late 19th Century, specifying the etiopathophysiology of anhedonia is a recent development. In this chapter, we selectively review genetic, neural, and epigenetic mechanisms of anhedonia, as well as environmental influences on the trait. Recent conceptualizations describe anhedonia as transdiagnostic and, therefore, not specific to depressive disorders. This observation helps to explain historically perplexing patterns of comorbidity between depression and other psychiatric conditions. Although assessment of anhedonia is relatively straightforward, its neural substrates present challenges for therapeutic intervention. We discuss these challenges and provide suggestions for future research.