• To examine the "serotonin hypothesis" of obsessivecompulsive disorder (OCD), we studied the behavioral and neuroendocrine effects of metachlorophenylpiperazine (mCPP), a serotonergic agonist, in patients with OCD and healthy controls. Twelve patients and 20 controls were given a single dose of 0.5 mg/kg of mCPP, administered orally under double-blind, placebo-controlled, random-assignment conditions. Following mCPP, but not following placebo, patients with OCD experienced a transient but marked exacerbation of obsessive-compulsive symptoms. Moreover, compared with healthy controls, patients exhibited greater other behavioral (but not endocrinologic or thermal) changes after mCPP. These findings are consistent with a special role for the neurotransmitter serotonin in OCD psychopathology.
Zohar J, Mueller EA, Insel TR, Zohar-Kadouch RC, Murphy DL. Serotonergic Responsivity in Obsessive-Compulsive DisorderComparison of Patients and Healthy Controls. Arch Gen Psychiatry. 1987;44(11):946-951. doi:10.1001/archpsyc.1987.01800230026006