Indication: Memory

Source:

Arch Intern Med, Nov 12, 2007;167(20):2184-90.

Research:

Oxidative stress contributes to brain aging, which is why the researchers in this study felt antioxidants, especially over the long term, might confer cognitive benefits. They started by adding cognitive testing to the Physicians' Health Study II (PHSII), a randomized trial of beta-carotene and other vitamin supplements for chronic disease prevention. PHSII is a continuation of the Physicians' Health Study (PHS), which had randomized male participants to low-dose aspirin and beta-carotene. Participants include those continuing their original beta-carotene assignment from the PHS, begun in 1982, and newer recruits randomized as of 1998. The beta-carotene arm (50 mg, alternate days) was terminated; follow-up is ongoing for the remaining arms. Near the close of the beta-carotene arm, researchers interviewed nearly 6000 participants older than 65 years to assess general cognition, verbal memory and category fluency. The primary endpoint was a global score averaging all tests (using z scores); the secondary endpoint was a verbal memory score combining results of four tests. Researchers compared mean cognition among those assigned to beta-carotene vs. placebo. Then they separately ex­amined new recruits and continuing participants.

Results:

Among 1904 newly recruited subjects (mean treatment duration, 1 year), cognition was similar across treatment assignments. Among 4052 continuing participants from the PHS (mean treatment duration, 18 years), the mean global score was significantly higher in the beta-carotene group than in the placebo group. On verbal memory, men receiving long-term beta-carotene supplementation also performed significantly better than the placebo group. Researchers said although they did not see an impact of short-term beta-carotene supplementation on cognitive performance, they believe long-term supplementation may provide cognitive benefits.