IN QUEST OF IDENTIFYING VULNERABILITY MARKERS FOR PSYCHIATRIC-DISORDERS BY ALL-NIGHT POLYSOMNOGRAPHY

Background: The persistence of a depression like sleep pattern in full y remitted depressed patients suggests that the pattern is a trait cha racteristic of sleep measurements. However, in the past, subjects have undergone investigation only after the onset of the disorder, and, th erefore, the altered sleep pattern may merely represent a biological s car. Methods: We polysomnographically investigated 54 healthy subjects who had no lifetime or current diagnosis of a psychiatric disorder bu t had at least one first-degree relative with major depression or a bi polar disorder and at least one further close relative with major depr ession, a bipolar disorder, or a schizophrenic disorder. Twenty unrela ted control probands without a personal and family history of psychiat ric disorders and 18 unrelated inpatients with major depression served as reference groups. Prior to investigation, all healthy subjects had been free of any prescription and nonprescription drug for at least 3 months. The depressed patients were free of drugs for at least 1 week . All subjects slept for 2 nights in the sleep research unit. The slee p of the second night was recorded and visually scored. Results: Analy sis of the individual sleep cycles in these subjects revealed both a r educed amount of slow wave sleep and increased rapid eye movement dens ity in the first sleep cycle. Discriminant analysis showed that 10 sub jects (18%) had sleep patterns similar to those of depressed patients. Conclusions: According to our observations, one fifth of the healthy subjects with a high genetic load for psychiatric disorders showed a c onspicuous (depression-like) sleep pattern. The follow-up will determi ne whether this sleep pattern indeed represents a trait marker indicat ing vulnerability.