A meta-analysis of three randomized controlled trials found no convincing evidence that omega-3 polyunsaturated fatty acids (PUFAs), when compared to placebo, were effective in the treatment of mild to moderate Alzheimer’s disease.

The researchers identified three similar studies including a total of 632 participants. As the human body cannot synthesize omega-3 PUFAs, they are categorized as essential fatty acids. The studies in the analysis used eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the most common omega-3. Dosing levels in each study were also similar, with levels of EPA and DHA between 1750-2300mg/day for each trial. All patients were categorized as having mild to moderate Alzheimer’s disease (AD). The trials lasted for 6, 12 and 18 months, respectively.

Results across each trial showed no significant therapeutic effect for omega-3 PUFAs treatment. Similarities were found in the Freund-Levi (2006) and Shinto (2014) studies at the 6 month follow-up, with no effect shown on cognition when measured with Mini-Mental State Examination (MMSE), (MD 0.18, 95% CI -1.05 to 1.41; 202 participants; 2 studies; I2 = 0%) — this evidence was graded as high.

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For the 12 month trial (Shinto, 2014), Alzheimer’s Disease Assessment Scale – Cognitive subscale (ADAS-Cog) at baseline was mean 32.10 (SD 6.4, n=11) and at the 6 month post-omega follow-up it was 33.8 (SD 9.6, n=12). MMSE score at baseline was 20.4 (SD 4.6, n=11) and at follow-up was 18.9 (4.4 n=12).

The lack of efficacy was also demonstrated in the only study to last 18 months (Quinn 2010), which was sponsored by the Alzheimer’s Disease Cooperative Study (ADCS) in co-operation with the National Institute of Aging (NIA) and DSM Nutritional Products. Results here showed a mean baseline ADAS-Cog score of 31.53 (SD 14.57, n=128) and mean at the 18 month post-PUFA score of 31.17 (SD 14.76, n=175)

The authors assert that their research found high quality evidence that omega-3 PUFA supplement is not effective in treating mild to moderate AD. They did however not discount that PUFAs may improve instrumental activities of daily living, when taken for a longer period of time, but this has to be confirmed in further trials.

They concluded, “we do not believe any further studies investigating the same treatment regimen in people with mild to moderate AD would yield any other results related to cognition and basic function. However, it remains unclear if people with other types of dementia or differing levels of severity of dementia would benefit from omega-3 PUFAs.”

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