ANXIETY AND AUTONOMIC REGULATION IN MAJOR DEPRESSIVE DISORDER - AN EXPLORATORY-STUDY

Spectral analysis of fluctuations in heart rate and blood pressure was employed to explore sympathetic and parasympathetic cardiovascular co ntrol mechanisms in relation to trait anxiety in major depressive diso rder. Sixteen drug-free female depressed patients were divided into tw o groups: those who were high on trait anxiety (HTA, n = 9) and those who were normal or low on trait anxiety (LTA, n = 7). In patients and age-matched female controls (n = 10), heart rate (HR), blood pressure (BP; Finapres device) and respiration were recorded during a period of supine rest (10 min), orthostatic challenge (60 degrees head-up tilti ng, 8 min), and post-orthostatic supine rest (8 min). Power spectra we re calculated over the last 4 min of these three situations for HR, sy stolic BP, as well as for respiration. Spectral density was assessed f or three frequency bands: low (0.02-0.06 Hz), mid (0.07-0.14 Hz) and h igh (0.15-0.50 Hz). Patients did not differ from controls during supin e rest. During orthostatic challenge, HTA patients showed significantl y more HR increase and suppression of high-frequency fluctuations of H R (suggesting stronger vagal inhibition) in comparison with the contro ls; this effect was accompanied by a significant increase in respirato ry frequency. Both patients groups did not show the normal increase in mid-frequency band fluctuations of BP during orthostatic challenge, i ndicating reduced sympathetic activation. Low-frequency fluctuations o f HR, as well as respiratory frequency during post-orthostatic supine rest of the HTA patients were significantly increased versus controls. This exploratory study indicates that trait anxiety may be a relevant factor when evaluating parasympathetic and sympathetic dysbalances in the state of a major depressive disorder.