Some, but not all, previous studies have shown that EPA is superior to placebo in treating unipolar or bipolar depression. Several caveats have, however, been issued when interpreting the results from these studies, including small and perhaps clinically irrelevant effect sizes, as well as potential publication bias. Generally, n-3 preparations with high doses of EPA relative to DHA have been shown to be more efficacious in treating depression. Interestingly, a double blind placebo-controlled RCT showed that that EPA (but not DHA) was effective in preventing interferon-alpha induced depression in hepatitis C subjects, consistent with the notion that EPA may have antidepressant effect in "inflammatory depression". In line with this notion, a recent a proof-of-concept study showed that high inflammation at baseline was associated with a better antidepressant effect of EPA, but not DHA, enriched n-3 compared to placebo. That study stratified subjects post-hoc based on inflammatory markers, whereas our approach will be to select study subjects a priori based on validated cut-offs for CRP. This is the next step in developing a personalized medicine paradigm for depression.