Neither vitamin E or selenium prevented dementia, according to the Prevention of Alzheimer’s Disease by Vitamin E and Selenium (PREADViSE) trial, which began as a double-blind randomized clinical trial in May 2002 and transformed into a cohort study from September 2009 to May 2015. The trial recruited 7,540 men, of whom 3,786 continued into the cohort study. The mean (SD) baseline age of the participants was 67.5 (5.3) years, with 3,936 (52.2%) reporting a college education or better, 754 (10.0%) blacks, and 505 (6.7%) Hispanics. Researchers found:

• Dementia incidence (325 of 7,338 men [4.4%]) was not different among the 4 study arms.
• A Cox model, which adjusted incidence for participant demographic information and baseline self-reported comorbidities, yielded hazard ratios of 0.88 for vitamin E, 0.83 for selenium, and 1.00 for the combination compared with placebo.