Antioxidant supplements vitamin E and selenium – taken alone or in combination – did not prevent dementia in asymptomatic older men, according to a study published online by JAMA Neurology.
Antioxidants as potential treatment for cognitive impairment or dementia have been of interest for years because oxidative stress has been implicated as a dementia pathway.
The Prevention of Alzheimer’s Disease by Vitamin E and Selenium (PREADViSE) clinical trial initially enrolled 7,540 older men who used the supplements for an average of about five years and a subset of 3,786 men who agreed to be observed longer. The men received either vitamin E, selenium, both or a placebo.
The incidence of dementia (325 of 7,338 men [4.4%]) was not different among the four study groups, according to the results in the article by Richard J Kryscio of the University of Kentucky, Lexington, USA, and coauthors.
Limitations of the study include losing about half of the participants to long-term follow-up during the transition from a randomised clinical trial to a cohort study. Publicity about the negative effect of supplements also may have played a role, according to the authors.
“The supplemental use of vitamin E and selenium did not forestall dementia and are not recommended as preventive agents. This conclusion is tempered by the underpowered study, inclusion of only men, a short supplement exposure time, dosage considerations and methodologic limitations in relying on real-world reporting of incident cases,” the article concludes.