The Munich vulnerability study on affective disorders: premorbid polysomnographic profile of affected high-risk probands.

BACKGROUND: The most characteristic alterations in the sleep electroencephalogram (EEG) during major depression are a shortened latency to rapid eye movement (REM) sleep and an elevated REM density. Because these changes persist in remission, they might represent vulnerability markers. To identify vulnerability markers, we investigated premorbid sleep EEG parameters in healthy high-risk probands (HRPs) with a positive family history of affective disorders. METHODS: We identified 136 depressed inpatients from referrals to our hospital who had first-degree relatives with an affective disorder as well as first-degree relatives with no current or lifetime history of psychiatric disorders. The latter (the HRP group) were investigated by polysomnography. During the follow-up period, 20 HRPs developed an affective disorder. Their premorbid sleep data were analyzed. RESULTS: Premorbid sleep EEG of affected HRPs showed an increased REM density (total night and first REM period) compared with the control group without personal or family history of a psychiatric disorder. CONCLUSIONS: Increased REM density can be observed not only in patients with depression, but also in their healthy relatives. Moreover, it is predictive for the onset of a psychiatric disorder. Therefore, it can be recommended as a possible endophenotype of these diseases.