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Daily vitamin and mineral supplementation improved cognition in older adults, the clinical trial showed.

The primary focus of the study was the effect of daily cocoa extract, which is rich in flavanols that prior research suggested might help preserve cognitive function. In the 3-year trial, daily cocoa extract had no effect on cognition (mean z score 0.03, 95% CI -0.02 to 0.08, P=0.28).

But over 3 years, a daily multivitamin-mineral supplement showed global cognition benefits compared with placebo (mean z score 0.07, 95% CI 0.02-0.12, P=0.007), reported Laura Baker, PhD, of Wake Forest University in Winston-Salem, North Carolina, and colleagues in

Episodic memory and executive function also improved.

The global effect of daily multivitamins seemed most pronounced in participants with cardiovascular disease. For people without cardiovascular disease history, mean z score was 0.06, 95% CI 0.01-0.11; for those with cardiovascular disease history, it was 0.14, 95% CI -0.02 to 0.31 (P=0.01).

"This is the first evidence of cognitive benefit in a large longer-term study of multivitamin supplementation in older adults," Baker said in a statement.

But it's too early to recommend a daily multivitamin to prevent cognitive decline, she cautioned.

"While these preliminary findings are promising, additional research is needed in a larger and more diverse group of people," Baker said. "Also, we still have work to do to better understand why the multivitamin might benefit cognition in older adults."

COSMOS-Mind, an ancillary study to the trial, tested whether either of two interventions -- daily cocoa extract capsules (500 mg/day) versus placebo, or multivitamin-mineral supplements versus placebo -- improved cognition in older adults randomly assigned to treatment using a two-by-two factorial design. The multivitamin was Centrum Silver manufactured by Haleon, which helped provide pills and packaging for the trial.

The study assessed cognition by telephone at baseline and annually. The primary outcome was a global cognition composite based on mean z scores from individual tests -- the Telephone Interview of Cognitive Status, Word List and Story Recall, Oral Trail-Making, Verbal Fluency, Number Span, and Digit Ordering -- relative to baseline.

A total of 2,262 participants were enrolled. Mean baseline age was 73, 60% were women, 89% were white, and 92% completed the baseline and at least one annual assessment. Participants had no history of myocardial infarction or stroke and were followed for 3 years.

Daily multivitamin-mineral supplementation led to relative improvements in both memory (mean change z score 0.06, 95% CI 0.002-0.13, P=0.04) and executive function (mean change z score 0.06, 95% CI 0.01-0.11, P=0.02). Modeling suggested that 3 years of multivitamin supplementation might slow cognitive aging by an estimated 60%, or 1.8 years.

The only other large, long-term randomized and cognition found no benefit among older male physicians who took a daily multivitamin.

Despite its positive findings, COSMOS-Mind leaves a number of questions unanswered.

"While the Alzheimer's Association is encouraged by these results, we are not ready to recommend widespread use of a multivitamin supplement to reduce risk of cognitive decline in older adults," Alzheimer's Association Chief Science Officer Maria Carrillo, PhD, said in a statement.

"Independent confirmatory studies are needed in larger, more diverse study populations," Carrillo pointed out. "It is critical that future treatments and preventions are effective in all populations."

The study had several limitations, Baker and co-authors acknowledged. Adherence to taking cocoa extract, multivitamins, or placebo throughout the study was monitored by self-report.

The researchers could not determine what components in the vitamin-mineral supplement led to better cognition. In addition, biomarker and genetic information about participants was not available.

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