A loss of interest in and withdrawal from all regular and pleasurable activities, often associated with depression. In short, it is an inability to experience pleasure. According to Freud, using his tripartite distinction between the id, ego and superego, deficits in the development of the id could lead to anhedonia. It has been suggested that anhedonia may be a marker for patients at risk of schizophrenia or schizophrenia spectrum disorders.
See Dysphoria, Ego, Id, Major depressive disorder, Pleasure-pain principle, Superego