Inadequate evidence for OTC supplements in preventing cognitive decline

1. There was inadequate evidence that any over-the-counter (OTC) supplement helped to prevent or delay decline in cognition.

2. The authors recommend further research using larger scale trials and clinically important outcomes to examine the effects of OTC supplements on cognition.

Evidence Rating Level: 1 (Excellent)   

Study Rundown: Concerns about cognitive decline due to dementia fuels an expanding business for OTC supplements claimed to impede and hinder cognitive decline.  However, evidence is uncertain regarding these claims.  The authors of this systematic review evaluated 38 trials studying the effectiveness of OTC supplements for the prevention or postponement of decline in cognition, mild cognitive impairment (MCI), or Alzheimer-type dementia.  The authors found that there was inadequate evidence that any OTC supplement helped to prevent or delay decline in cognition.  Therefore, health care providers cannot currently recommend any OTC supplement as a protective measure against cognitive decline.  The authors recommend further research using larger scale trials and clinically important outcomes to examine the effects of OTC supplements on cognition.

A strength of the study is that it provides an updated report of the evidence regarding the use of OTC supplements for prevention of dementia or cognitive decline.  Limitations include the evaluation of trials that had short follow-up, high attrition, and greatly varied outcome measures for cognition.

Click to read the study in Annals of Internal Medicine

Relevant Reading: Does taking vitamin, mineral and fatty acid supplements prevent cognitive decline? A systematic review of randomized controlled trials

In-Depth [systematic review]: The authors used EMBASE, the Cochrane Central Register of Controlled Trials, Ovid MEDLINE, and PsycINFO to search for pertinent literature that was published from January 2009 to July 2017.  To find articles published prior to 2009, the authors examined the citations of certain studies and systematic reviews.  Qualifying studies were in English, had ≥6 months of follow-up, had adult participants who did not have dementia, and evaluated outcomes in cognition for OTC supplements compared to active control or placebo.  The 38 trials that were included had a low to medium risk of bias.  The OTC supplements that were evaluated included B vitamins, vitamin C or beta-carotene, vitamin D plus calcium, ginkgo biloba, multi-ingredient supplements, omega-3 fatty acids, and soy.  Only a small number of studies evaluated the effects of OTC supplements on MCI or clinical Alzheimer-type dementia.  Of those that did, no benefit was shown.  Folic acid and vitamin B12 taken daily was linked to statistically significant results on memory tests, but the clinical significance was uncertain.  Evidence of moderate strength indicated that vitamin E does not improve cognition.  Beta-carotene, vitamin C, vitamin D plus calcium, folic acid alone or in addition to other B vitamins, ginkgo biloba, multivitamins or other supplements with multiple ingredients, omega-3 fatty acids, and soy seem to have no effect on decreasing the risk of cognitive decline, due to evidence regarding the effects of these supplements being of low strength or inadequate.  There was seldom any report of adverse events.

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