Supplemental doses of B vitamins were found to slow the progress of dementia in a new British clinical trial, again raising hopes that they may prove to be a defense against Alzheimers disease.This is a very dramatic and striking result, commented lead researcher A. David Smith, PhD, of Oxford University. Its much more than we could have predicted. It is our hope that this simple and safe treatment will delay development of Alzheimers in many people who suffer from mild memory problems.Smith and colleagues cautioned, however, that larger trials are needed before their findings could be applied to clinical practice. They also stressed that the B vitamins were administered in such high doses that this is a drug, not a vitamin intervention.B vitamins are known to reduce blood levels of an amino acid, homocysteine, linked to risk of Alzheimers disease and other forms of dementia. But results from previous studies of B vitamins effect on cognitive function have been mixed. For example, a 2006 New Zealand clinical trial of high levels of B vitamins failed to find any cognitive benefit better than a placebo.The British researchers targeted mild cognitive impairment (MCI), which affects 16% of those over age 70 worldwide-and half of those progress to Alzheimers disease. Mild cognitive impairment may not interfere with daily life, but is characterized by issues with memory, language and other mental functions. The progress of the condition can actually be measured by scanning the brain, so Smith and colleagues compared brain shrinkage over two years between those on the B vitamins and those on placebo.Overall, 271 older individuals with mild cognitive impairment enrolled in the study, and 168 had cranial MRI scans at the start and finish. Participants were randomly assigned to two equal groups. One group received a placebo, while the others got daily doses of 0.8 milligrams of folic acid (double the RDA), 0.5 milligrams of vitamin B12 (more than 200 times the RDA) and 20 milligrams of vitamin B6 (12-13 times the RDA).When the brain scans were compared over time, those in the high-dose B vitamin group showed an average rate of brain atrophy of 0.76% a year. That was significantly better than those in the placebo group, whose brains shrank by an average 1.08% per year. Although the trial was not focused on cognitive function per se, researchers also reported that greater rates of brain atrophy were associated with lower cognitive test scores at the end of the trial.As expected, homocysteine levels played a role in the results. Those with the highest levels of homocysteine at the start of the study saw the most benefit from the B vitamins; their brains shrank at only half the rate of those in the control group.The accelerated rate of brain atrophy in elderly with mild cognitive impairment can be slowed by treatment with homocysteine-lowering B vitamins, Smith and colleagues concluded, reporting their findings in the Public Library of Science (PLoS) One journal. Since accelerated brain atrophy is a characteristic of subjects with mild cognitive impairment who convert to Alzheimers disease, trials are needed to see if the same treatment will delay the development of Alzheimers disease.
TO LEARN MORE:PLoS One,online at www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0012244. Alzheimers Association,www.alz.org; 24-hour helpline, (800) 272-3900. National Institute on Aging Alzheimers Disease Education and Referral (ADEAR) Center www.nia.nih.gov/Alzheimer , (800) 438-4380.