Overview
- A randomized, double-blind, placebo-controlled trial of 365 adults aged 55–80 found that daily 2,000 mg DHA supplements did not improve memory, overall cognition, or slow hippocampal shrinkage.
- Investigators confirmed target engagement by measuring a roughly 17% average rise in cerebrospinal fluid DHA at six months, showing the supplement reached the brain but produced no clinical benefit.
- Participants were selected for low dietary fish intake and about 47% carried the APOE4 gene, so the result applies most directly to this higher-risk, low-fish-intake group rather than all ages or populations.
- Study authors say the finding shifts emphasis away from standalone pills toward whole-diet and lifestyle strategies for lowering Alzheimer’s risk and toward research on brain mechanisms for using omega-3s.
- The team plans mechanistic work and drug-focused approaches to help the brain better utilize omega-3s, and the null result raises questions for the large fish-oil supplement market and consumer expectations.