Folate, vitamin B-12 deficiency tied to lower cognitive function

Low plasma vitamin B-12 and folate are independently associated with worse cognitive function, according to a study of Puerto Rican adults. Notably, vitamin B-12 deficiency is not uncommon and correlates with poorer cognitive function.

This cross-sectional analysis included 1,408 participants (mean age, 57.1 years) from the Boston Puerto Rican Health Study. The authors evaluated cognitive function through a comprehensive test battery and derived a global composite score. They then assessed plasma folate, vitamin B-12, and methylmalonic acid (MMA) in fasting blood samples.

After adjustment for covariates, high plasma folate and high plasma vitamin B-12 each correlated positively with global cognitive score (logged values: β, 0.063, 95 percent confidence interval [CI], –0.0008 to 0.127; p=0.053 and β, 0.062, 95 percent CI, 0.009–0.12; p=0.023, respectively; across tertiles: β, 0.002, 95 percent CI, 0.00005–0.004; p=0.044 and β, 0.00018, 95 percent CI, 0.00001–0.0003; p=0.036, respectively).

Vitamin B-12 deficiency (<148 pmol/L or MMA >271 nmol/L) was detected in 9 percent of participants; none of them were folate deficient (<4.53 nmol/L). Deficiency significantly correlated with lower cognitive score (β, –0.119, 95 percent confidence interval [CI], –0.208 to –0.029; p=0.009) compared with higher vitamin B-12.

The interaction for vitamin B-12 deficiency and high plasma folate could not be examined due to the small sample size (<1 percent of the cohort) in this category.

“More attention should be given to identification and treatment of vitamin B-12 deficiency in this population,” the authors said. “Additional, larger studies are needed to examine the effect of vitamin B-12 deficiency in the presence of high exposure to folic acid.”