Slow wave sleep deficits as a trait marker in patients with schizophrenia

Background: Among the sleep abnormalities found in schizophrenia, slow wave sleep deficits have been found to persist even after the resolution of active psychotic symptoms. Further, such abnormalities are observed in young healthy individuals at high risk of schizophrenia, which suggest that slow wave sleep deficits might be trait marker in schizophrenia. Methods: Sleep EEG was recorded in 20 right handed patients aged 18-45 years with ICD-10 DCR diagnosis of schizophrenia, 14 first degree relatives and 20 age and sex matched controls. Patients were rated on Positive and Negative Syndrome Scale (PANSS) and Brief Psychiatric Rating Scale (BPRS) for assessment of psychopathology. Results: There was significant difference between the three groups in total sleep period (p<.01), total sleep time (p<.01), stage shifts (p<.05), stage 1 percentage of total sleep time (p<.05), stage 2 duration (p<.05), stage 3 latency (p<.05), stage 4 duration (p<.01) and stage 4 percentage of total sleep time (p<.01). There was significant positive correlation of REM percentage of total sleep time with BPRS total score (r_s=488, p=029) and PANSS positive score (r_s=583, p=007), whereas significant negative correlation of REM latency was found with BPRS total score (r_s=-640, p=002) and PANSS positive score (r_s=-657, p=002) in the patients. Conclusions: Slow wave sleep deficits are a possible trait marker in patients with schizophrenia, which needs replication in further studies.