We investigated whether the human growth hormone (HGH) response to catecholamine depletion differs between fully remitted patients with major depressive disorder and healthy control subjects. Fourteen unmedicated subjects with remitted major depressive disorder (RMDD) and 11 healthy control subjects underwent catecholamine depletion with oral α-methylparatyrosine (AMPT) in a randomized, placebo-controlled, double-blind crossover study. The main outcome measure was the serum level of HGH. The diagnosis × drug interaction for HGH serum concentration was significant (F1,23 = 7.66, P < 0.02). This interaction was attributable to the HGH level increasing after AMPT administration in the RMDD subjects but not in the healthy subjects. In the RMDD sample, the AMPT-induced increase in HGH concentration correlated inversely with AMPT-induced anxiety symptoms as assessed using the Beck Anxiety Inventory (r = −0.63, P < 0.02). There was a trend toward an inverse correlation of the AMPT-induced HGH concentration changes with AMPT-induced depressive symptoms as measured by the BDI (r = −0.53, P = 0.05). Following catecholamine depletion, the RMDD subjects were differentiated from control subjects by their HGH responses. This finding, together with the negative correlation between HGH response and AMPT-induced anxiety symptoms in RMDD subjects, suggests that AMPT administration results in a deeper nadir in central catecholaminergic transmission, as reflected by a greater disinhibition of HGH secretion, in RMDD subjects versus control subjects.
From the *University Hospital of Psychiatry, University of Bern, Bern, Switzerland; and †Department of Psychiatry, Oklahoma University School of Medicine; and Laureate Institute for Brain Research; Tulsa, OK.
Received January 28, 2012; accepted after revision January 17, 2013.
Reprints: Gregor Hasler, MD, University Hospital of Psychiatry, University of Bern, Bolligenstrasse 111, 3000 Bern, Switzerland (e-mail: email@example.com).
This research was supported by the Intramural Research Program of the National Institutes of Mental Health and the University Hospital and Hermann Klaus Foundation, Zurich.