The men and women participants were survivors of the Scottish Mental Surveys of 1932 and 1947, which conducted intelligence tests in Scottish School Children. From 1997-1999, participants in the two groups–born in 1921 and now aged 76-78, and born in 1936 and now aged 61-63–took part in the study. Cognitive status was measured by standardized tests that assessed nonverbal intelligence, speed of information processing, pattern recognition, and general cognitive ability, and plasma concentrations of tHcy, folate, and vitamin B-12 were determined.
The older group (born in 1921) had increased levels of tHcy, which correlated both with lower serum folate and vitamin B-12 concentrations and with lower cognitive test scores. Those who had higher plasma concentrations of folate and B-12 scored higher on 4 of the 6 cognition tests.1 Among the group born in 1936, higher folate concentrations correlated with higher scores on one of the assessment tests, but otherwise no effects of B vitamins or tHcy were apparent.
These findings have important implications for the design of preventative nutritional strategies aimed at delaying cognitive decline in the elderly. In an accompanying editorial, Smith discusses findings in previous studies that both vascular dementia and Alzheimer disease are associated with high levels of tHcy, which may have a neurotoxic effect. He suggests that clinical trials should be developed with the aim of lowering tHcy in the elderly by administration of folic acid or vitamin B-12, which may lower tHcy and prevent those with mild cognitive impairment from developing Alzheimer disease.
Duthie, Susan J et al. Homocysteine, B vitamin status, and cognitive function in the elderly. Am J Clin Nutr 2002;75:908-13.
Smith, A David. Homocysteine, B vitamins and cognitive deficit in the elderly. Am J Clin Nutr 2002;75:785-6.
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American Journal of Clinical Nutrition