The effects of eicosapentaenoic acid in tardive dyskinesia: A randomized, placebo-controlled trial

ObjectiveWorldwide, conventional antipsychotic medication continues to be used extensively, and tardive dyskinesia (TD) remains a serious complication. The primary objective of the present study was to compare the efficacy of EPA versus placebo in reducing symptoms of TD.MethodThis was a 12-week, double-blinded, randomized study of ethyl-EPA 2 g/day versus placebo as supplemental medication, in patients with schizophrenia or schizoaffective disorder, with established TD.ResultsEighty-four subjects were randomized, of whom 77 were included in the analysis. Both the EPA and placebo groups displayed significant baseline to endpoint improvements in Extrapyramidal Symptom Rating Scale dyskinesia scores, but there were no significant between-group differences (p = 0.4). Response rates (≥ 30% improvement in TD symptoms) also did not differ significantly between EPA-treated subjects (45%) and placebo-treated subjects (32%) (p = 0.6). However, a post-hoc linear mixed model repeated measures analysis of variance indicated an effect for treatment group and duration of TD. The EPA-treated patients had significantly greater mean reductions in dyskinesia scores initially, although this was not sustained beyond 6 weeks.ConclusionsThis trial failed to demonstrate an antidyskinetic effect for ethyl-EPA 2 g/day on the primary efficacy measure. However, a modest and transient benefit is suggested in patients with more recent onset of TD. The lack of clear-cut efficacy could be explained on the basis of the dose of EPA being too low, the study being underpowered, TD being too chronic in the majority of cases, differences in dietary fatty acid intake, or that EPA lacks an antidyskinetic action.