Low folate and vitamin B12, elevated homocysteine predict cognitive decline

Japanese researchers are the latest to show an association between low levels of the B-complex vitamins folic acid and vitamin B12 and the development and rate of cognitive decline in older men and women. The researchers also found an association between cognitive decline and high plasma homocysteine, an amino acid that rises in concentration when folic acid levels are inadequate; it has been shown to be an independent risk factor for developing atherosclerosis when elevated.
The scientists at Yagoya University Graduate School of Medicine recruited 28 men and 71 women aged 60 to 94 for the current research. Blood samples were analyzed for plasma homocysteine, serum folic acid and vitamin B12, and other factors. Participants underwent examinations for cognitive function, and were also tested for depression.
Thirty one percent of the subjects had cognitive function test scores that were suspicious for cognitive impairment, and 11 percent were categorized as depressed. High homocysteine levels and low folic acid and vitamin B12 levels were associated with a greater adjusted risk of cognitive impairment, but not depression. Previous research shows that elevated homocysteine levels have been associated with the development of dementia and Alzheimer's disease. A lack of B12 or Folic Acid has been associated with mental decline and shrinkage of the brain with age. The authors note that “It is conceivable that keeping appropriate levels of B vitamins and homocysteine throughout life are useful to prevent cognitive decline in later life. From this standpoint, the appropriate supplementation of B vitamins needs to be considered as the relevant issue for all age groups in Japan." The study is published in the December, 2008 issue of the journal Clinical Nutrition.