Paroxetine treatment of pathological gambling: a multi-centre randomized controlled trial.

Previous studies have suggested the efficacy of serotonergic agents in the treatment of pathological gambling. The aim of the present study was to determine whether treatment with paroxetine in a large sample of subjects with pathological gambling would effectively diminish the severity of gambling symptoms. A 16-week, double-blind, placebo-controlled trial was conducted at five outpatient academic research centres in two countries (USA and Spain). Seventy-six outpatients (mean age 45.4+/-10.6 years; 30 women, 46 men) with pathological gambling were randomized to acute treatment with paroxetine in flexible daily dosages of 10-60 mg/day (n=36) or placebo (n=40). The primary outcome measure was the Clinical Global Impressions scale. Both the paroxetine- and the placebo-treated groups demonstrated comparable improvement at 16 weeks (59% response rate in the paroxetine group, 49% rate in the placebo group; chi squared=0.737; d.f.=1; P=0.390). Paroxetine consistently resulted in a greater percentage of responders at each study visit compared to placebo but failed to demonstrate statistical superiority to placebo on scores on the Clinical Global Impressions scale, the Yale-Brown Obsessive-Compulsive Scale Modified for Pathological Gambling, or the Gambling Symptom Assessment Scale. High rates of symptom improvement were observed in pathological gamblers receiving either paroxetine or placebo after 16 weeks. Paroxetine consistently demonstrated an advantage over placebo on the Clinical Global Impressions scale; however, a larger sample size may have registered significant differences.