Homocysteine—an amino acid associated with inflammation, cardiovascular disease, osteoporosis, and other health problems—has also been linked to cognitive decline and dementia. Researchers at the University of Oxford have reported that elevated homocysteine levels are associated with approximately double the risk of cognitive impairment and dementia. Vitamins B12, B6, and folic acid are required for the metabolic conversion of homocysteine into less harmful compounds.
Further insight comes from a longitudinal study published in the American Journal of Clinical Nutrition (November 2007; Vol. 86, No. 5:1384–1391). This study followed more than 1,600 participants over a 10-year period. Researchers assessed vitamin B12 status using holotranscobalamin and methylmalonic acid—both sensitive indicators of B12 availability—and measured cognitive function at three points during the study.
Higher vitamin B12 status was associated with a slower rate of cognitive decline. Specifically, doubling holotranscobalamin levels was linked to a 30% reduction in the rate of cognitive decline over the study period. In contrast, folic acid levels did not appear to significantly influence cognitive decline in this population.
