Longitudinal assessment of negative symptoms in schizophrenia/schizoaffective patients, other psychotic patients, and depressed patients.

This study assessed differences in negative symptom presentation between schizophrenia/schizoaffective, other psychotic, and depressed patients over a 10-year followup period. One hundred fifty individuals with schizophrenia or schizoaffective disorders (SZ/SZAF), other psychotic disorders (OP), and depressed patients (DP) were assessed at index hospitalization, then reassessed at 4.5-year, 7.5-year, and 10-year followups. SZ/SZAF patients significantly differed from DP patients in frequency and persistence of negative symptoms but were not significantly different from the OP group. Negative symptoms were not associated with depression in any diagnostic group. Dosage, but not simple use, of conventional antipsychotic medications was related to severity of symptoms in the SZ/SZAF group. Although negative symptoms were typically most severe and most common in the SZ/SZAF subjects in comparison to the DP patients, there were few statistically significant differences in the phenomenology of negative symptoms between the OP and SZ/SZAF groups. The data are consistent with a model that identifies negative symptoms as common to mental illnesses generally, with particularly high rates in psychotic illnesses.