Electroencephalographic sleep in unipolar depressive subtypes: support for a biological and familial classification

A tripartite classification of unipolar disease based on family history has been proposed by Winokur. In this study, we sought to investigate whether the familial pure depressive disorder (FPDD) and the sporadic depressive disorder (SDD) populations could be differentiated on the basis of baseline EEG sleep as effected by a tricyclic pharmacological probe. A subject group consisting of 26 females and 10 males yielding 18 FPDD/SDD pairs matched for age was selected. Both groups of patients demonstrated a considerable amount of sleep continuity disturbance with an overall sleep efficiency of 80.5 per cent in the pure depressive (FPDD) group and 83 per cent in the sporadic (SDD) group. Examination of the rapid eye movement (REM) sleep variables revealed the usual shortened REM latency as well as increased REM activity and REM density changes. However, the only significant difference between the two groups on baseline was the presence of more stage 3 and 4 sleep in the sporadic group, but stage 3 and 4 sleep was found in less than 40 per cent of the total sample. In contrast, analysis of the first two nights of EEG sleep on 50 mg of amitriptyline demonstrated several significant findings between the two groups. While considerable REM sleep suppression occurred in both groups, REM activity, REM intensity, and the number of REM periods were significantly more suppressed in the pure group than the sporadic group. Application of these variables led to a successful discrimination of 75 per cent of all the cases. These findings suggest a hyper-reactivity of sleep in patients with FPDD to a pharmacological probe.