Anhedonia

In psychology, anhedonia is a patient's inability to experience pleasure from normally pleasurable life events such as eating, exercise, and social/sexual interactions.

It is most commonly seen in the mood disorder depression, although it is also seen in schizophrenic disorders and other mental disorders.

Anhedonia is often experienced by drug addicts following withdrawal; in particular, stimulants like cocaine and amphetamines cause anhedonia and depression by depleting dopamine and other important neurotransmitters.