A placebo-controlled cross-over trial of adjunctive EPA in OCD

Several clinical studies showed beneficial effects of omega-3 fatty acids in major affective disorders, including resistant depression. Some antidepressants are also effective, albeit less so, in obsessive-compulsive disorder (OCD). We therefore undertook a preliminary placebo-controlled cross-over trial of adjunctive eicosapentaenoic acid (EPA) in OCD. Eleven patients with current obsessive-compulsive disorder, who were on a stable maximally tolerated dose of SSRI with no further improvement over at least the last two months, were recruited. Subjects were randomly allocated to begin 6 weeks of placebo (2 g liquid paraffin per day) followed by 6 weeks of 2 g of EPA or EPA followed by placebo. Patients continued their prior SSRIs at the same dose. Assessments were performed with the Yale-Brown Obsessive-Compulsive Scale (YBOCS), and the Hamilton Rating Scales for depression (HAM-D) and anxiety (HAM-A). There were no effects of order of treatment. Time had a main effect of YBOCS scores; mean scores declined from 26.0 (±5) to 17.6 (±6) by week 6 on placebo and to 18.5 (±4) on EPA. There were no effects on HAM-D and HAM-A. No clinically relevant side effects were reported. The results of this study suggest that adjunctive EPA is ineffective against OCD.