Increases in Homocysteine Are Related to Worsening of Stroop Scores in Healthy Elderly Persons: A Prospective Follow-Up Study

Abstract

Elevated blood levels of homocysteine have been associated with cerebrovascular disease and cognitive impairment. The authors' objective was to determine the relationship between cognitive changes and variations in tHcy levels over time in healthy elderly volunteers. This prospective cohort study was conducted in healthy community-dwelling older adults without cerebrovascular disease at baseline and followed them for 2.3 years. Cobalamin, red blood cell folate, total serum homocysteine (tHcy), and creatinine levels were measured and recorded. Cognitive measures included the Mini Mental State Examination, California Verbal Learning Test, Mattis Dementia Rating Scale, and Stroop Neuropsychological Inventory. At baseline, participants with elevated tHcy levels had lower Stroop scores (72.7 vs 85.35, p <.05) than did participants with normal tHcy levels. The tHcy levels correlated significantly with Stroop scores at baseline and follow-up. At follow-up, tHcy levels had increased in 104 participants (group I) and decreased in 76 participants (group II). Compared to mean baseline values, the mean tHcy in both groups had changed significantly at follow-up (p <.05 and p <.001, respectively). Participants in group I had significantly lower Stroop scores in multivariate analyses at follow-up than at baseline. The scores of participants in group II at follow-up were not significantly different than their scores at baseline. The rate of change of tHcy levels and the rate of change of the Stroop scores were significantly correlated (r = -0.264, p <.001) after multivariate analysis. Stroop scores decreased by 22% at follow-up in participants whose tHcy levels increased by 40% from baseline to follow-up. Elevated tHcy levels and increases in tHcy during a short period of time are associated with decreased Stroop scores in otherwise cognitively normal elderly volunteers.