Cognitive Status According to Homocysteine and B-Group Vitamins in Elderly Adults.

Objectives: To determine the association between hyperhomocysteinemia and cognitive function, taking into account the effect of B group vitamin (BGV) deficiency.

Design: Cross-sectional.

Setting: Memory Clinic, S. Anna University Hospital, Ferrara, Italy.

Participants: Elderly individuals (≥65) (N = 318; 44 normal cognition, 127 with cognitive impairment, 147 with dementia) divided into four groups according to plasma homocysteine (high vs normal) and BGV (normal vs deficit) levels.

Measurements: Cognitive, clinical, biochemical, functional, and neuroimaging parameters were evaluated.

Results: Hyperhomocysteinemia (>15 μmol/L) was associated with a higher prevalence of cognitive and functional impairment and dementia (odds ratio (OR) = 1.98, 95% confidence interval (CI) = 1.13-3.48), independent of BGV status and other confounders. Participants with hyperhomocysteinemia with normal BGV status had the worst functional status and the highest prevalence of dementia (high homocysteine/normal BGV vs normal homocysteine/normal BGV: OR = 3.20, 95% CI = 1.65-6.21). Homocysteine levels were correlated negatively with folate and vitamin B12 levels and glomerular filtration rate and positively with free thyroxine and uric acid levels (model coefficient of determination = 0.43).

Conclusion: Hyperhomocysteinemia was associated with worse cognitive and functional status and dementia independently of BGV levels. Approximately half of participants with hyperhomocysteinemia had normal BGV levels, suggesting that other unmeasured factors might be associated with high homocysteine levels.