The incidence of negative symptoms in early schizophrenia, mania and other psychoses.

Despite increasing interest in negative symptoms in schizophrenia there has been little work on their incidence in early schizophrenia or in other psychoses. This study examined 79 nondepressive psychotics within 2 years of onset of illness, diagnosed by Research Diagnostic Criteria and assessed for negative symptoms using the Scale for the Assessment of Negative Symptoms. Marked negative symptoms were observed in nearly half of patients diagnosed as suffering definite schizophrenia and were rarely found in other psychoses. Negative symptoms were not significantly correlated with positive symptoms, depression or exposure to neuroleptics, but were correlated with developing extrapyramidal side effects.