EEG sleep diagnosis of medical disease in depression.

The diagnosis of medical disease in the context of a depressive syndrome which may mimic medical illness has traditionally relied on a combination of exhaustive medical screening and neuropsychological testing. When 10 patients with primary depression were compared to 10 patients whose depression occurred in the context of concurrent medical disease, a single EEG sleep variable, total phasic REM activity (RA), correctly identified 95% of all 20 patients as either primary depressives or medical patients with depression. Conventional psychiatric assessment and neuropsychological testing were significantly less powerful discriminators among this sample.