Posted on 24th Sep 2010 @ 8:57 AM

Brain atrophy is the partial or complete wasting away of the brain. This is a process which occurs naturally in cognitively healthy individuals however this rate of progression is enhanced in those with mild cognitive impairment and even more so in patients suffering from Alzheimer’s disease. Evidence has suggested that raised homocysteine levels have been associated with an increased risk of brain atrophy. The homocysteine level in the body is largely determined by certain B vitamins such as folate, Vitamin B6 and Vitamin B12.

A recent randomised, double blind placebo controlled trial from the Oxford Project for Memory and Ageing was conducted in which 168 individuals with mild cognitive impairment were either supplemented with the active treatment of  folic acid (0.8mg/day), vitamin B6 (20mg/day) and vitamin B12 (0.5mg/day) or the placebo (dummy pill) for 24 months. The change in the rate of brain atrophy was measured via MRI scans taken both at the beginning and the end of the study. A significant difference in the mean rate of brain atrophy in the active treatment group (0.76%) and in the placebo group (1.08%) was noted. The response was greater in those with high initial homocysteine levels with the rate of brain atrophy in some cases being >50% lower for those on the active treatment. Hence this study concluded that the accelerated rate of cognitive decline in mild cognitive decline can be slowed by treatment with homocysteine lowering B vitamins.

B vitamins such as folate (pulses, green leafy vegetables), vitamin B6 (baked potatoes, bananas and pulses) and vitamin B12 (meat, poultry and fish) are found in a wide range of foods and should be taken in quantities of 200ug, 1.4mg and 2.5ug respectively. It is worth noting that the supplement in the above study contained extremely high doses of the aforementioned vitamins, around 300 times greater than the RDA for vitamin B12 and 4 times greater for folate. These are amounts not accessible from the normal diet and should not be taken unless under medical supervision. Some studies suggest that such high doses of folate may fuel the growth of early stage cancer. Folate is involved in DNA repair; hence in high doses it may cause damage in excess of ongoing DNA repair. Similarly certain medicines such as methotrexate used for the treatment of rheumatoid arthritis and psoriasis are also thought to be folic acid antagonists, hence the side effects of methotrexate are similar to that of folic acid deficiency.

 There is certainly evidence to suggest that B vitamins play an important role in lowering homocysteine and hence slows the rate of accelerated brain atrophy. However caution is necessary with regard to the dosage and it is important not to exceed the recommend daily allowance unless under medical supervision. This study is of large significance with around 1.5million people in the UK suffering from mild cognitive impairment with a 50% chance of going on to develop dementia.