B vitamins and the brain

A recent study (the VITACOG study) conducted at the University of Oxford has shown that B vitamins appear to slow cognitive and clinical decline in people with mild cognitive impairment (MCI). This two year randomised, placebo-controlled trial, examined the effect of treatment with vitamins B6, B12 and folic acid on brain shrinkage and memory function in people over 70 years with MCI.

MCI is defined as cognitive decline greater than that expected for an individual’s age, but does not notably interfere with daily life activities. The prevelance of MCI is around 16% in those over 70 years old; with half of those progressing to develop dementia within five years.

The dose of B vitamins compared to placebo was 800 mcg folic acid, 500 mcg vitamin B12 and 20 mg vitamin B6.

Previous studies have identified an association between:
• low levels of B vitamins and cognitive impairment
• low levels of B vitamins and total homocysteine (tHcy) and
• higher than average tHcy and poor cognitive performance.

Elevated levels of homocysteine (an amino acid) in the blood is also associated with atherosclerosis (hardening and narrowing of the arteries), as well as an increased risk of heart attacks, strokes and blood clot formation.

Elevated tHcy is widely recognised as a risk factor for both cognitive impairment and Alzheimer’s disease, with tHcy found to be significantly higher in those with Alzheimer’s than those without.

The primary aim of the VITACOG trial was to determine if lowering tHcy via the use of B vitamins over two years would slow the rate of brain atrophy.

The results are impressive:
• B vitamins reduced tHcy by 30%
• B vitamins stabilised executive and planning functions
• B vitamins provided significant benefit in terms of global cognition, episodic memory and semantic memory.

In participants with high baseline tHcy treated with placebo significant decline occurred during the trial: this decline was prevented in those treated with B vitamins.

The VITACOG trial is truly a landmark study, being the first to show clear benefit of an intervention with vitamin supplementation, with the potential to prevent the progression of MCI to Alzheimer’s disease.