PLASMA ARGININE-VASOPRESSIN AND MOTOR-ACTIVITY IN MAJOR DEPRESSION

Background: Previously, we found that mean plasma concentrations of ar ginine vasopressin (AVP), but not of oxytocin (OT), were higher in dep ressed patients than in healthy controls. Plasma AVP concentrations we re positively correlated to clinically rated psychomotor retardation. To further explore this previously reported relation we studied psycho motor retardation by means of an activity monitor, which is a more fin e-focused and more objective instrument to analyze motor retardation t han a clinical rating scale. Methods: Plasma AVP and OT concentrations , and day- and nighttime wrist activity were measured in 48 in- and ou tpatients with major depression and 30 healthy controls during a perio d of5 consecutive days and nights. Results: Principal components analy sis revealed three components of motor activity: motor activity during wakefulness, motor activity during sleep, and the awake/sleep time ra tio. In patients and controls an inverse relationship between plasma A VP concentrations and motor activity during wakefulness was found. Pat ients with elevated AVP plasma levels showed increased motor activity during sleep. Conclusions: These results suggest that high plasma AVP levels are related to the clinical picture of daytime psychomotor reta rdation and nighttime motor activity in major depression. Mean plasma OT concentrations were not related to measures of motor activity. (C) 1998 Society of Biological Psychiatry.