Sleep-related memory consolidation and the effects of olanzapine in patients with schizophrenia

Cognitive impairments such as memory deficits and sleep disturbances are common clinical features of schizophrenia. We recently described a correlation of visuospatial memory impairments and a decrease in the amount of slow wave sleep (Göder et al., J Psychiatr Res 2004). The aim of this study was to test the effects of the second generation atypical antipsychotic agent olanzapine on sleep and sleep-related memory consolidation. We studied 26 patients with schizophrenia on stable antipsychotic medication with amisulpride (age range 19–44 years, seven women). Immediately before polysomnography and the morning after we performed neuropsychological tasks including verbal and visual declarative memory tests. Before the third night in the sleep laboratory patients received either olanzapine or a placebo. We could confirm our previous results of a significant positive association of slow wave sleep and declarative memory performance in patients with schizophrenia. Olanzapine caused a significant increase in the amount of slow wave sleep, but not an improvement in sleep-related memory consolidation. We suggest, that other untoward effects of olanzapine neutralized putative positive effects on memory performance.