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Antioxidant supplements do not prevent Alzheimer disease

Antioxidant supplements, including vitamin E, selenium and a combination of the two, did not effectively prevent Alzheimer disease in asymptomatic older men.

“Multiple mechanisms associated with disease onset and progression have been described, and one key mechanism implicated in [Alzheimer disease] is oxidative stress, which may be modifiable through diet and/or antioxidant supplements,” Richard J. Kryscio, PhD, of University of Kentucky, and colleagues wrote. “Antioxidant use as a potential treatment for cognitive impairment or dementia has been of interest for many years.”

To assess efficacy of antioxidant supplements for dementia prevention in asymptomatic older men, researchers conducted the Prevention of Alzheimer’s Disease by Vitamin E and Selenium (PREADViSE) trial. PREADViSE began as a double-blind randomized clinical trial (n = 7,540) in May 2002 and transitioned into a cohort study (n = 3,786) from September 2009 to May 2015. Study participants had a mean age of 67.5 years.

Researchers randomly assigned participants to receive vitamin E, selenium, vitamin E and selenium, or placebo. Researchers used a two-stage screen to evaluate participants for dementia. Men were evaluated by an enhanced two-stage cognitive screen by telephone. Participants were encouraged to see their clinician if screen results were positive.

Dementia incidence did not vary between treatment arms.

A cox model adjusted for demographics and baseline self-reported comorbidities indicated hazard ratios of 0.88 (95% CI, 0.64-1.2) for vitamin E, 0.83 (95% CI, 0.6-1.13) for selenium and 1 (95% CI, 0.75-1.35), compared with placebo.

“The PREADViSE trial illustrates many of the difficulties for undertaking prevention trials: uncertainty of medication dose, mechanisms of action, and proof of target engagement; proper selection of a diverse population that can be observed for a realistic period to yield enough cases of dementia to determine success or failure of the intervention; use of appropriate assessment tools and methods of accurate diagnosis; and use of effective ways for maintaining participation and assuring adherence in the study over time,” Steven T. DeKosky, MD, of University of Florida in Gainesville, and Lon S. Schneider, MD, of University of Southern California, Los Angeles, wrote in an accompanying editorial. “The research team addressed these issues as well as they could, especially considering it was an add-on study. Finding efficient and cost-saving ways to address these issues in long-term, disease-modifying trials must be major goals for research groups around the world.” – by Amanda Oldt

Disclosure: The researchers report no relevant financial disclosures.