Sleep EEG in Korsakoff's psychosis and Alzheimer's disease.

All-night sleep EEGs were compared in the following age-equivalent groups: seven men with Korsakoff's psychosis (KP), six men and two women with presumptive Alzheimer's disease, and six healthy men and three healthy women. KP patients had significantly increased intermittent time awake than both controls and Alzheimer patients, and shorter REM latency minus time awake than controls. Alzheimer patients had significantly reduced delta sleep than controls. Differences in the pattern of sleep EEG abnormalities may be due to different pathogenic mechanisms, but their utility in differential diagnosis requires further study.