24-hour profile of plasma norepinephrine in affective disorders

The circadian rhythm of plasma norepinephrine (NE) was investigated in the depressed (major affective disorder, DSM III; n = 12), recovered (after 3 weeks of treatment using usual antidepressant drugs; n = 12) and normal (volunteers, age and sex matched; n = 10) states. Data analysis (based on the evaluation of circadian parameters, on the chronogram method and on the chronobiological analysis) revealed a clear NE circadian rhythm in normal subjects, a rhythm which was disturbed in depression, with amplitude reduction and abnormal phase position. These abnormalities tended to disappear during recovery since circadian parameters were similar to those of controls. These circadian abnormalities could be linked to the impairment of the peripheral and central catecholaminergic systems. They may also support the chronobiological hypothesis of affective disorders.