As we age it’s common for cognitive functions to decline due to the increased rate of brain atrophy. According to previous studies, the amino acid homocysteine increases with age and is a marker for cognitive impairment, brain atrophy and dementia. High levels of homocysteine has also been associated with cardiovascular disease.

Because plasma concentrations of homocysteine can be reduced by dietary intake of B vitamins, researchers at the University of Oxford in England set out to test whether vitamin B supplementation would slow the rate of brain atrophy in elderly participants with mild cognitive impairment.

For the randomized, double-blind experiment, researchers David Smith et al. recruited 646 participants over the age of 70 who had mild cognitive impairment. The subjects were split into two groups and were either treated over the course of 24 months with high doses of folic acid (0.8 mg/d), vitamin B12 (0.5 mg/d) and vitamin B6 (20 mg/d), while the control group was treated with placebo.

Adherence to treatment was determined by measuring plasma vitamins and counting returned tablets. MRI scans were done at the start and end of the trial on a subset of the participants to assess the rate of atrophy.

The effect of vitamin B and homocysteine levels on brain atrophy in the elderly

Of the 168 participants that took part in the MRI scan, brain atrophy was found to be 0.76% per year in the vitamin B group and 1.08% per year in the placebo group. The trial supported the notion that homocysteine levels was associated with rate of atrophy.

They found that the rate of atrophy in participants with homocysteine levels greater than 13 µmol/L was reduced by 53% for the vitamin B group. Cognitive test scores were also shown to be higher for participants with lower rate of atrophy. Based on these results, Smith, et al., conclude that increased rate of brain atrophy in elderly individuals with mild cognitive impairment can be slowed by vitamin B intake.

Since Alzheimer’s disease, the most common form of dementia, starts with mild cognitive impairment, the researchers believe additional studies should be conducted to determine whether vitamin Bs will delay development of the disease.