Association between delta waves during sleep and negative symptoms in schizophrenia - Pharmaco-EEG studies by using structurally different hypnotics

We examined the effects of benzodiazepine (BZD) hypnotics and zopiclone (ZP C), a nonbenzodiazepine hypnotic, on sleep and psychiatric symptoms in schi zophrenia, as well as the clinical correlates of these variables. Seven mal e schizophrenic patients chronically taking neuroleptics together with BZD were studied. We replaced BZD with ZPC and performed polysomnography (PSG) and Brief Psychiatric Rating Scale (BRPS) scoring before and after an 8-wee k ZPC treatment. The replacement of BZD with ZPC increased the mean amplitu de of high-amplitude low-frequency delta waves on the frontal derivation re cognized by period-amplitude analysis, and it decreased the BPRS negative-s ymptom score. Under the BZD treatment, the negative-symptom score correlate d inversely with the mean amplitude of high-amplitude low-frequency delta w aves. This correlation was weak and not significant under the ZPC treatment . Therefore, delta waves during sleep have a close correlation to negative symptoms in schizophrenia, and such a correlation could be influenced by hy pnotics. Although these are preliminary findings, it was suggested that, co mpared with BZD, ZPC might be a beneficial hypnotic in regard to both sleep and negative symptoms of chronic schizophrenic patients.