Low angiotensin-converting enzyme activity (kininase II) in cerebrospinal fluid of schizophrenics.

Angiotensin-converting enzyme (kininase II, E. C., 3.4.15.1) activity was present in lumbar cerebrospinal fluid of paranoid schizophrenic patients and psychiatrically healthy controls. Both schizophrenics under neuroleptic treatment and drug-free patients had low cerebrospinal enzyme activity when compared with controls. No correlation existed with the scores of the Brief Psychiatric Rating Scale. A negative correlation of enzyme activity with cerebrospinal levels of both dopamine and noradrenaline was detected. Our findings suggest the possibility of a central alteration of the metabolism of neuropeptides in paranoid schizophrenia.