Anhedonia is a defining characteristic of drug dependence64, and criteria for major depressive disorder — which includes anhedonia as a core symptom — are met by many drug-addicted individuals (for example, 50% of cocaine-addicted individuals65). The strong association between mood and substance use disorders is not limited to depression66; for example, emotional distress is a risk factor for drug relapse67. However, research on how altered emotion processing is implicated in substance use disorders is in its infancy68,69, as discussed below (Supplementary information S5 (table)).
