After MRI studies suggested the efficacy of ethyl-EPA in reducing the progressive brain atrophy in Huntington disease (HD), trials were conducted to test its efficacy as a treatment for HD. Trials that continued for 6 months did not find any significant improvement, urging discontinuation of the drug. However, trials that continued for 12 months indicated improvement of motor functions in these patients.

We searched 12 electronic databases to find randomised clinical trials relevant to our inclusion criteria. After screening, only five papers were included. Continuous and binary variables were analysed to compute the pooled mean difference (MD) and risk ratio (RR), respectively. Quality effect model meta-analysis was used as a post hoc analysis for studies at 12 months.

Meta-analysis indicated that ethyl-eicosapentaenoic acid (EPA) has no significant effect on any scale of HD at 6 months. At 12 months, two studies suggested significant improvements of the Total Motor Score and Total Motor Score–4 in both fixed and quality effect models [MD = −2.720, 95% CI (−4.76, –.68), p = 0.009; MD = −2.225, 95% CI (−3.842, −0.607), p = 0.007], respectively. Maximal chorea score showed significant results [MD = −1.013, 95% CI (−1.793, −0.233), p = 0.011] in only fixed-effect model, while no improvement was detected for Stroop colour naming test or symbol digit modality.

Meta-analysis indicated a significant improvement of motor scores only after 12 months. These results should be interpreted cautiously because only two studies had assessed the efficacy of ethyl-EPA after 12 months with one of them having a 6-month open-label phase.