Anhedonia - a general nosology correlation of a dysfunction of the dopaminergic reward system?

The dopaminergic reward system is activated by primary rewarding factors such as food,sexual activity and parental care. Its activation enhences the occurency of behaviors which induced the stimulation of dopaminergic neurotransmission. Indications of a dysfunction of the dopaminergic reward system are found in major depression, schizophrenia,and addictive disorders. It has been hypothesized that dysfunction of the dopaminergic reward system is associated with anhedonia,the inability to experience pleasure. However, animal studies indicate that a reduction of centra I dopaminergic neurotransission is associated with a decrease in incentive salience of reward-indicating stimuli and not with anhedonia per se. Sensitization of dopaminergic neurotransmission, on the other hand, seems to induce cue-dependent craving in addicted patients. In schizophrenia, phasic, stimulus-dependent dopamine release in the striatum may playa role in the abnormal attribution of salience to previously neutral stimuli.