Study
CNS target engagement of high-dose DHA supplementation in older adults at risk for dementia: a randomised, double-blind, placebo-controlled trial.
In 365 older adults without dementia, high-dose DHA reached cerebrospinal fluid but did not improve cognition or brain structure over 24 months.
Summary Does taking high-dose DHA protect thinking and brain structure as we age? Show / hide ↓
Researchers randomly gave 365 adults aged 55 to 80 either high-dose DHA, an omega-3 fat, or a look-alike placebo for 24 months. Everyone had no dementia and generally ate little DHA. After six months, DHA levels rose in cerebrospinal fluid, the fluid around the brain and spinal cord, showing that it reached the brain. However, it did not improve thinking skills or brain structure compared with the placebo after two years.
What this means for you: This study does not support buying high-dose DHA to prevent dementia or preserve brain structure. It changed a brain-related measurement, but that change did not improve outcomes people would notice.
moderate evidenceThis phase IIa trial tested high-dose DHA in adults aged 55-80 years without dementia who had low dietary DHA intake. The 24-month study at the University of Southern California was randomised, double-blind and placebo-controlled. Of 739 people screened, 365 were randomised: 181 to the LP arm and 184 to the no-LP arm. Mean age was 66.4 years, 58% of participants were female, 39% were Hispanic, and 47% carried APOE epsilon4. The supplied abstract does not state the DHA dose or fully reproduce the eligibility text, but it reports the main biochemical result. At six months, DHA increased the cerebrospinal-fluid DHA/arachidonic-acid ratio versus placebo by 0.19 (95% CI 0.16 to 0.21). This demonstrates central nervous system target engagement. It did not translate into detectable differences in cognition or brain structure over 24 months. The trial was funded by the National Institute on Aging and the ADDF. For people looking for dementia prevention or brain-ageing benefits, the key result is negative on clinical and structural outcomes despite a clear biomarker change.
High-dose DHA achieved CNS target engagement, but no differences in cognition or brain structure were observed over 24 months.
The positive result was a cerebrospinal-fluid biochemical ratio, while cognition and brain structure did not differ. The abstract does not state the DHA dose in the supplied text, and participants were selected for low dietary DHA intake.
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