Modulation of sleep: A new approach of treating memory impairment in schizophrenia?

Cognitive impairments and sleep disturbances are common clinical features of schizophrenia. As sleep plays an important part in consolidation of memory, we investigated whether of not there is an interrelationship between alterations in particular polysomnographic night sleep measures and memory performance. We studied 17 patients with schizophrenia (ICD-10) on stable antipsychotic medication (age range 22 to 44 years; 7 women) and 17 healthy controls. Immediately before polysomnography and the following morning we performed a neuropsychological test-battery including Rey-Osterrieth complex figure test, a test for recall of spatial location memory, and a mirror tracing skill. Preliminary results demonstrate that in comparison to healthy controls the schizophrenic patients showed a significant increase in sleep onset latency and number of awakenings and a significant decrease of the amount of slow wave sleep (SWS). In the patient group SWS and sleep efficiency were correlated with next morning recall of the Rey figure (significantly) and of spatial location (trend). Further research is needed to investigate the question, whether or not treatment of these sleep disturbances is suitable to improve memory impairment in schizophrenia.