Selecting individuals with high homocysteine (in the absence of other potentially accountable factors) focused the study on those with inadequate folate status, according to an accompanying editorial by Martha Clare Morris, Sc.D., and Christine C. Tangney, Ph.D., both of the Rush Institute for Healthy Aging in Chicago.
Participants were randomly assigned to three years of double-blind treatment with placebo or 800 ?g/day folic acid(Drug information on folic acid), which the authors said "is regarded as a low dose for a clinical trial." Treatment was effective with serum folate concentrations increasing by 576% and plasma homocysteine falling by 26% for the folic acid group compared with placebo.
At baseline, both groups had similar scores on a battery of cognitive tests for memory, sensorimotor speed, complex speed, information processing speed, and word fluency.
Three years later, the results were significantly different comparing the folic acid versus placebo groups. The findings were (mean Z score difference):