Depression, parkinsonian symptoms, and negative symptoms in schizophrenics treated with neuroleptics

To determine whether depression and neuroleptic-induced parkinsonism confound the clinical assessment of negative symptoms in schizophrenics, we evaluated 45 outpatient schizophrenics for depression, parkinsonian symptoms, and negative symptoms using standard clinical rating scales. Neuroleptic and anticholinergic dose and plasma activity were also determined. Associations between negative symptoms and these clinical and drug variables were examined using a multivariate statistical model. Negative symptoms were significantly correlated with several parkinsonian symptoms, some vegetative features of depression, and with anticholinergic dose. No significant correlations were found between negative symptoms and cognitive features of depression, or neuroleptic and anticholinergic plasma activity. These findings suggest that assessment criteria for negative symptoms, depression, and drug-induced parkinsonism overlap in treated schizophrenics. Strategies for differentiating these clinical syndromes are discussed.