Mild cognitive impairment affects many people as they age and is a common condition in those over 70 years of age. With the rising number of baby boomers, this is likely to become a major public health issue. The causes of cognitive decline is multifactorial but what is known is that both brain shrinkage and higher blood homocysteine levels, an amino acid that is part of normal metabolism, are associated with various forms of dementia including Alzheimer’s disease.
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What is homocysteine?
Homocysteine is an amino acid that is produced as part of normal metabolism. Abnormally high homocysteine levels are associated with many poor health conditions such as cardiovascular disease including congestive heart failure, poor bone health, and cognitive impairment including Alzheimer’s disease. Homocysteine levels are normally kept low because the body converts it to other substances via a process that requires the B vitamins folate, B6 and B12.
What did the study find?
Following up on previous research, this study looked at the impact of supplementation with B vitamins on brain shrinkage, brain function and the area of the brain affected by Alzheimer’s disease. Participants were randomized into one of two groups: placebo and vitamin treatment: 800 mcg of folic acid, 20 mg of vitamin B6, and 500 mcg of vitamin B12; amounts considered to be ‘high’ compared to what is needed to prevent overt vitamin deficiencies but consistent with what can be found in everyday supplements, amounts without any safety concerns.
After two years, brain shrinkage was found in both groups keeping in mind that there is some amount of shrinkage that naturally occurs with aging, so it was expected to see some atrophy. What was impressive about the results is that there was an average of 87 percent less grey matter shrinkage (they type of brain tissue that is responsible for visual and spacial learning, memory and organization of thoughts, and is most affected by Alzheimer’s disease) in those receiving the B vitamins.
Those with high homocysteine levels not only saw an improvement with the B vitamins, but when high homocysteine levels dropped within the normal range, brain shrinkage was reduced by almost 90 percent.
Supplementation with folate, vitamins B6 and B12 in amounts higher than the RDA (Recommended Dietary Allowance) was able to reduce age-associated brain shrinkage. The greatest benefit was seen in those who were at an increased risk for dementia as a result of high homocysteine levels by decreasing the loss of grey matter and brain shrinkage in areas of the brain associated with Alzheimer’s disease. The study did not, nor can it demonstrate that intakes of B vitamins at these levels prevent Alzheimer’s disease, but certainly showed a clinical effect with promising results.
Photo credit: Sash Alexander