REM density in the differential diagnosis of psychiatric from medical-neurologic disorders: a replication.

The discriminatory power of rapid eye movement (REM) density in 61 outpatients with medical, neurologic, and psychiatric disorders and 8 noncase controls was assessed. REM density was significantly lower in a group of patients with medical-neurologic disease as compared with psychiatric and control subjects without evidence for such disease. Furthermore, low scores discriminated depressions occurring in the context of somatic disease when compared with those in the absence of such disease. The differences between groups were not accounted for by age or sex. The cutoff REM density score of 12.56, based on the 99% lower confidence limit of the noncase controls, provided the highest sensitivity (0.82) without loss of specificity (0.80). It was concluded that REM density may have merit as a general measure of diffuse central nervous system pathology, whether primary or secondary to widespread systemic disease. The findings of Kupfer's group are upheld and extended to a broader medical and neuropsychiatric population than in the original Pittsburgh study.