Vitamins to prevent cognitive decline.

The Problem

A well-nourished, ambulatory 62-year-old man presents for a general medical exam. He has a history of coronary artery disease and hypertension. He tells you that he has been reading about life extension (mostly the works of Aubrey de Grey). He has also been surfing the Internet and believes that multivitamins help prevent memory problems associated with aging. He tells you that he has purchased expensive vitamin supplements and asks you whether they will prevent him from forgetting the names of his grandchildren.

The Question

In older patients, do multivitamins prevent cognitive decline, compared with placebo?

The Search

You go to PubMed (www.pubmed.gov) and enter "vitamins" and "cognitive function" and limit the search to randomized, controlled trials. Your search yields a relevant study (see box at right).

Our Critique

The study provides additional evidence that multivitamins and multiminerals do not prevent cognitive decline among nonselected elderly patients. As the authors point out, vitamin and mineral levels achieved through the supplements given in this study could be reached with a well-balanced diet. The possibility exists that the tests used were not sensitive enough to pick up minor changes in cognitive function.

Importantly, studies of B vitamins and antioxidants at doses higher than used in this study have not demonstrated any beneficial effects. However, patients at increased risk for nutritional deficiencies (e.g., nursing home patients, the very elderly) have been shown to have improvement in cognitive function with supplements.

Clinical Decision

You suggest to your patient that as long as he is eating a well-balanced diet, the vitamin and mineral supplements may be doing nothing more than making expensive urine. You conclude that 12 months of vitamin supplementation may not be preventing the natural aging processes of his central nervous system. You further suggest that vitamins also appear to do nothing to prevent natural aging on the outside and emphasize this by showing him the updated picture of the authors of this column (see updated color photo).

G. McNeill et al.

Effect of multivitamin and multimineral supplementation on cognitive function in men and women aged 65 years and over: A randomised controlled trial. Nutrition Journal 2007;6:10.

Design and Setting: MAVIS (Mineral and Vitamin Intervention Study), a large randomized, placebo-controlled trial, was done at primary health centers in northeast Scotland between February and December 2002.

Subjects: Subjects were men and women aged 65 years and older who had not taken vitamin, mineral, or fish oil supplements within 3 months of recruitment or water-soluble vitamins other than [B.sub.12] in the past month. Potential subjects were recruited by their physicians at their practice or by an experienced nurse or dietician at their home.

Intervention: Eligible subjects were randomized to a vitamin/mineral supplement containing 800 mcg vitamin A, 60 mg vitamin C, 5 mcg vitamin D, 10 mg vitamin E, 1.4 mg thiamine, 1.6 mg riboflavin, 18 mg niacin, 6 mg pantothenic acid, 2 mg pyridoxine, 1 mcg vitamin [B.sub.12], 200 mcg folic acid, 14 mg iron, 150 mcg iodine, 0.75 mg copper, 15 mg zinc, and 1 mg manganese; or matching placebo. Subjects were instructed to take one tablet daily for 12 months with compliance checked at monthly intervals.

Outcomes: Cognitive function was assessed in all participants by digit span forward and verbal fluency tests. Tests were conducted face to face at recruitment and over the telephone at the end of the intervention. The digit span forward test is conducted by asking the subject to repeat a sequence of random digits up to a nine-digit sequence. Digit span is a test of attention and immediate memory. The verbal fluency test is conducted by asking the participant to name words beginning with certain letters (either P, R, and W or C, F, and L) in an exactly timed 1-minute period; this tests speed of processing and information retrieval. Intention-to-treat analysis was used. Risk of vitamin deficiency was assessed using a nutrition risk questionnaire.

Results: In this study, 456 subjects (239 men and 217 women) received the supplement and 454 subjects (240 men and 214 women) received the placebo. Across both groups, 290 subjects were 75 years of age or older. No significant differences were observed between groups at baseline. Compliance with the tablets for the 12-month period was 78% in both supplemented and placebo groups. No significant differences in baseline test results were seen between the supplement and placebo groups.

Overall, improvement was observed in the digit span forward test scores from baseline to 12 months but not in the verbal fluency scores. However, no differences were observed in the digit span or verbal fluency between the two groups.

Weak but nonsignificant improvements with supplementation were observed in subjects older than 75 years and among subjects with an increased risk for vitamin deficiency. These two subgroups were selected for analysis a priori.

BY JON O. EBBERT, M.D., AND ERIC G. TANGALOS, M.D.

DR. EBBERT and DR. TANGALOS are with the Mayo Clinic in Rochester, Minn. They have no conflict of interest to report. To respond to this column or suggest topics for consideration, write to Dr. Ebbert and Dr. Tangalos at our editorial offices or e-mail them at imnews@elsevier.com.