[T]o date the majority of studies evaluating omega-3s for averting or curtailing cognitive decline in human participants have failed to show benefits… Now, [this] team says a small clinical trial provides important clues about this discrepancy, in the first Alzheimer’s prevention study to compare levels of omega-3s in the blood with those in the central nervous system. The findings, “Brain delivery of supplemental docosahexaenoic acid (DHA): A randomized placebo-controlled clinical trial,” published in EBioMedicine, suggest that higher doses of omega-3 supplements may be needed to make a difference, because dramatic increases in blood levels of omega-3s are accompanied by far smaller increases within the brain.
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The 2-gram dose of DHA in this study far exceeded what has been used in major clinical trials testing the preventive power of omega-3s, which typically administer 1 gram or less daily.
“If you use a lower dose, you can expect a less-than-10-percent increase in omega-3s in the brain, which may not be considered meaningful,” continues [researcher Hussein] Yassine.
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The preliminary data from the current study was intriguing enough that the scientists were able to attract funding for a larger trial for which recruitment is underway. Following 320 participants over two years, it will examine whether high doses of omega-3s can slow cognitive decline in carriers of the APOE4 gene.
