Leafy Green Vegetables May Help Keep Brains Sharp Through Aging

A team led by Katherine L. Tucker, PhD, director and professor ofthe Nutritional Epidemiology Program at the Friedman School ofNutrition Science and Policy at Tufts, studied a group of Boston-areamen who were members of the ongoing Normative Aging Study (NAS). Tuckerand her colleagues found that men who obtained more folate in theirdiets showed significantly less of a decline in verbal fluency skillsover the course of three years than did men with lower dietary folateintake.

High folate levels, both in the diet and in the blood, alsoappeared to be protective against declines in another category ofcognitive skills known as spatial copying. To test this, the 50- to85-year-old study participants were asked to copy various shapes andfigures, and their drawings were assessed for accuracy. "The men took aseries of cognitive tests at the beginning of the study period and thenrepeated those tests three years later," explained Tucker. "We comparedtheir first and second scores, reviewed their responses to dietaryquestionnaires, and took blood samples in order to see if nutrientlevels in the diet and the blood were related to changes in cognitiveperformance."

In an earlier study with the same NAS group, whichcorroborated the findings of other investigators, the Tufts researchteam observed that high homocysteine--a known blood marker ofcardiovascular disease risk--was associated with lower cognitive testscores.

Since folate supplementation can help reduce blood levels ofhomocysteine, it was thought that this might explain folate'sbeneficial effects. However, in the current study, the effects offolate were independent of its impact on homocysteine, which turned outto be more strongly associated with tests of memory.

"Unlike our prior work with this population, in which weobserved an association between low folate levels and lower cognitivetest scores at one point in time, this study looks at the effects ofthese nutrients over time." Tucker says, "That is an important step inestablishing causality."

Tucker KL, Qiao N, Scott T, Rosenberg I, Spiro A, III. AmericanJournal of Clinical Nutrition. 2005; 82: 627. "High homocysteine andlow B vitamins predict cognitive decline in aging men: the VeteransAffairs Normative Aging Study."