Lack of effect of anxiety on total plasma MHPG in depressed patients

This report was undertaken to test the noradrenergic deficiency hypothesis of depression and the postulated increase in noradrenergic activity associated to anxiety states. A possible dual effect of both depression and anxiety on total plasma MHPG levels was hypothesized and assessed in anxious and non-anxious depressed patients. The findings show a decrease in plasma MHPG levels in depressed patients whatever their degree of anxiety. There was no difference in total plasma MHPG levels either between anxious and non-anxious depressed patients or between low and high anxiety to depression ratio (ADR) depressed patients. Following antidepressant drug-treatment, a decrease in plasma MHPG was found. A positive correlation between the drug-induced decrease in NA activity and the severity of depression was observed, and suggested a relationship between the severity of depression and the instability of the NA system. No correlation between the drug-induced decrease in plasma MHPG and the degree of anxiety was found. The results do not suggest out an effect of anxiety on total plasma MHPG levels in depressed patients.