Cardiovascular tests of autonomic function and sympathetic skin responses in patients with major depression.

To assess the function of the autonomic nervous system in major depression, a series of cardiovascular tests, together with the recording of sympathetic skin response, were performed in 18 depressed patients (melancholic type, DSM-III-R criteria) and in 18 healthy control subjects. Depressed patients showed significantly poorer performance in Valsalva's, deep breathing, and lying to standing manoeuvres than controls, indicating an impairment of parasympathetic function. Depressed patients developed a significantly larger sympathetic skin response than controls during the lying to standing and hand grip manoeuvres, whereas cardiovascular sympathetic performance (as assessed by the responses to hand grip, cold, mental arithmetic, explosive sound, or hyperventilation) was similar in both groups. The results are compatible with the view that a diminished parasympathetic reactivity, and presumably an increased sympathetic reactivity, occur in patients with major depression.