Neurology · 3 h ago
Two-year trial finds no cognitive benefit from high-dose DHA supplements
In a randomized, double-blind trial of 365 adults aged 55–80 at elevated Alzheimer’s risk, daily DHA supplements raised cerebrospinal-fluid DHA levels but did not improve cognitive test results or prevent hippocampal shrinkage over two years. The findings apply to the population studied and do not assess omega-3 intake from food.
- Trial enrolled 365 adults aged 55–80 at elevated Alzheimer’s risk.
- CSF DHA rose 17% at six months with supplementation.
- No cognitive advantage or protection against hippocampal shrinkage was found.
- Dietary omega-3 intake was not tested as an intervention.
Researchers at Keck Medicine of USC randomly assigned 365 adults aged 55–80, who rarely ate fish and were considered at elevated risk of Alzheimer’s disease, to daily DHA supplements or placebo. The trial was double-blind and lasted two years; 47% of participants carried the APOE4 variant. The supplement provided 2,000 mg of DHA daily. Outcomes included cognitive tests and hippocampal volume on brain imaging. Researchers also measured DHA in cerebrospinal fluid.
At six months, cerebrospinal-fluid DHA had risen by an average of 17% in the supplement group. However, after two years, participants taking DHA showed no significant advantage over placebo on cognitive tests, and supplementation did not prevent hippocampal shrinkage.
The findings do not support high-dose DHA supplements as a means of preventing cognitive decline or Alzheimer’s-related brain changes in similar older adults. They do not establish whether eating fish or following a broader dietary pattern affects brain health, and the lifestyle factors discussed by the researchers were not tested in this trial. The study was supported by the National Institutes of Health and the Alzheimer’s Drug Discovery Foundation.
In practice
For adults aged 55–80 at elevated Alzheimer’s risk who rarely ate fish, this randomized, double-blind trial found that 2,000 mg of DHA daily for two years raised cerebrospinal-fluid DHA but did not improve cognitive test performance or prevent hippocampal shrinkage versus placebo. The findings do not support using high-dose DHA supplements specifically to prevent cognitive decline in a similar population. The trial did not test omega-3 intake through food, other dietary patterns, or longer-term outcomes, so it cannot establish their effects.
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eBioMedicine (via ScienceDaily): Millions take fish oil for brain health. A two-year study found no benefit ↗This is an automated AI-condensed summary that has not yet been reviewed by an editor. Always consult the full item at the original source.