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B vitamins may slow cognitive decline

September 17, 2011

According to a new study from the UK, daily doses of folic acid, vitamin B12 and vitamin B6 can slow cognitive and clinical decline in people with mild cognitive impairment.

In the randomized controlled trial, 266 participants with mild cognitive impairment over the age of 70 were randomly assigned to receive a daily dose of 0.8mg folic acid, 0.5mg vitamin B12 and 20mg vitamin B6 or a placebo for two years (1). Changes in cognitive or clinical function were analyzed. The study results showed that the concentration of mean plasma homocysteine in those treated with B vitamins was 30% lower in relation to placebo. The B-vitamin group showed stabilized executive function as well as significant benefit in global cognition, episodic memory and semantic memory in participants with homocysteine levels above the median (11.3mmol/L). In contrast, the placebo group underwent significant cognitive decline. Clinical benefit occurred for people in the B-vitamin group who had high homocysteine concentrations at the beginning of the study.

The researchers concluded that a treatment with B vitamins appears to slow cognitive and clinical decline in people with mild cognitive impairment, in particular in those with elevated homocysteine levels. Further trials would be needed to see if this treatment will slow or prevent progression from mild cognitive impairment to dementia.

Mild cognitive impairment (MCI) is a syndrome defined by a cognitive decline greater than that which is expected for an individual’s age and education level, yet does not interfere notably with activities of daily life. There are about 5 million people in the USA and 14 million in Europe with this condition. Because about half of those with MCI will develop dementia within 5 years of diagnosis, there is an urgent need to identify ways of slowing cognitive decline in this population group. Low levels of B vitamins have been associated with cognitive impairment (2). The biological pathways involved are probably related to formation of the amino acid homocysteine and its increased plasma concentrations with age. Since patients with Alzheimer’s disease have higher plasma concentrations than normal older people, increased homocysteine is recognized as a risk factor for cognitive impairment and Alzheimer’s disease (3).

References

  1. Jager de C. A. et al. Cognitive and clinical outcomes of homocysteine-lowering B-vitamin treatment in mild cognitive impairment: a randomized controlled trial. Int J Geriatr Psychiatry. 2011; 26(10).
  2. Smith A. D. The worldwide challenge of the dementias: a role for B vitamins and homocysteine? Food Nutr Bull. 2008; 29:143–172.
  3. Oulhaj A. et al. Homocysteine as a predictor of cognitive decline in Alzheimer’s disease. Int J Geriatr Psychiatry. 2010; 25:82–90.