A new study by researchers at the University of California, San Diego, found no difference in the cognitive decline of Alzheimer’s patients with mild to moderate forms of the condition who took high-dose vitamin B supplements, compared to those taking a placebo.

The research focused on vitamin B because vitamin B9, vitamin B6 and B12 are known for their ability to reduce levels of homocysteine in the body. Alzheimer’s sufferers tend to have high homocysteine levels and this has also been linked to an increased risk of heart disease. Homocysteine is an amino acid produced by the body.

The purpose of the study was to determine whether large doses of three vitamins – B6, B12, and folic acid (a form of B9) – might slow the progression of Alzheimer’s disease. The study looked only at patients who already suffered Alzheimer’s disease.  

For the study, Paul Aisen, the study’s lead author and a professor in the department of neurosciences at the University of California San Diego, and colleagues randomly assigned 409 people with mild to moderate Alzheimer’s disease to a combination of folic acid, vitamin B12 and vitamin B6, or an inactive placebo pill.

Over 18 months, researchers found that although the supplements reduced levels of the amino acid called homocysteine, which tends to be higher in people with Alzheimer’s, there was no reduction in disease progression.

“We were successful in lowering homecysteine, but it had absolutely no effect on the clinical symptoms of Alzheimer’s disease,” the study’s lead author said.

The researchers measured the cognitive scores using the Alzheimer’s Disease Assessment Scale and found no significant difference in the rate of cognitive decline of patients taking supplements and those receiving a placebo. One perturbing finding of the study was that the participants taking high-dose vitamin D supplements suffered more depressive symptoms than those taking placebo pills.

High doses of vitamin B supplements will not bring a significant improvement for patients with Alzheimer’s disease, Aisen’s team concluded. The findings were published in the Oct. 15 issue of the Journal of the American Medical Association.

The researchers said people with Alzheimer’s should not take high doses of the vitamins to avoid mental decline.

According to the estimates of the U.S. National Institutes of Health, there are currently about 4.5 million Americans with Alzheimer's disease. One in 20 people with ages ranging from 65 to 74 and almost half of those with ages over 85 are affected by the terrible condition.

Alzheimer’s is a terminal and degenerative disease for which there is no known cure. The most commonly symptom is memory loss, as well as difficulty to remember recently learned facts. Sometimes, the condition could not be diagnosed for years. The best way to reduce the risk of dementia is to eat a balanced diet, to exercise regularly and to give up smoking and drinking, which influence the development of the Alzheimer’s.