Plasma Arginine Vasopressin and motor activity in major depression

Investigated the relationship between the mean plasma concentration of arginine vasopressin (AVP), oxytocin (OT) and clinically rated psychomotor retardation. 48 inpatients and outpatients with major depression (aged 22-77 yrs) and 30 healthy controls (aged 19-73 yrs) participated. Plasma AVP and OT concentrations were measured 3 times a day (8:00, 16:00, and 23:00 hrs) and day and nighttime wrist activity were measured during a period of 5 consecutive days and nights. Principal component analysis revealed 3 components of motor activity: motor activity during wakefulness, motor activity during sleep, and the awake/sleep time ratio. In patients and controls an inverse relationship between plasma AVP concentrations and motor activity during wakefulness was found. Patients with elevated AVP plasma levels showed increased motor activity during sleep.