Depression in schizophrenia: are neuroleptics, akinesia, or anhedonia involved?

To investigate the presence of a full depressive syndrome in schizophrenia years after the acute phase and factors linked to these depressive syndromes, 75 schizophrenia and schizoaffective patients and 32 patients with bipolar affective disorders were studied prospectively at index hospitalization and followed up 4.5 years later as part of the Chicago Followup Study. Over 30 percent of the schizophrenia patients showed full depressive syndromes during the followup year. Schizophrenia patients on neuroleptics were significantly more likely to show full depressive syndromes than those not on neuroleptics during the followup year. This relationship held after the level of posthospital psychosis was controlled. The data suggest that neuroleptic use is one factor linked to the depressive-like syndromes found in the posthospital phase in non-chronic schizophrenia samples. The results did not support the view that these depressive-like syndromes are only a function of akinesia, although they suggest that akinesia is probably one factor involved. The data indicate a strong link between neuroleptic use and anhedonia. These data suggest that one factor involved in the depressive-like symptoms found in schizophrenia patients could be interference by neuroleptics with the mesolimbic dopamine reinforcement system or the dopamine reward system.