Effects of catecholamine depletion with AMPT (alpha-methyl-para-tyrosine) in obsessive-compulsive disorder

Background: Several lines of evidence suggest that brain dopamine function may contribute to some obsessive-compulsive (OC) phenomena. The effects of catecholamine depletion were examined in drug-free patients with obsessive-compulsive disorder (OCD). Methods: The tyrosine hydroxylase inhibitor alpha- methyl-para-tyrosine (AMPT) and diphenhydramine hydrochloride (placebo) were administered for three consecutive days, one week apart, to 6 drug-free adult OCD patients without a personal or family history of chronic tics, in a double-blind, randomized design. The effects of AMPT and placebo on OC, depression, anxiety and global clinical symptoms were assessed. Results: AMPT produced no clinically or statistically significant change in any behavioral ratings, including OC symptom severity, compared with placebo. Conclusions: Acute reduction of catecholamine levels does not seem to affect OC symptoms in drug-free patients with OCD. Studies of catecholamine depletion with AMPT in patients with comorbid OCD and chronic tics may be of considerable neurobiological and clinical interest.