High homocysteine blood levels are being linked with the risk of Alzheimer's disease, vascular dementia and stroke, according to researchers at Queen's University of Belfast in Ireland.

Folic acid and B vitamins help lower homocysteine levels but have not been proven to actually reduce the risk of Alzheimer's disease or the other conditions.

Researchers studied 83 patients with Alzheimer's disease, 64 stroke patients and 78 patients with vascular dementia. These patients, average age 75, were compared to 71 individuals without the three conditions who were within the same age range.

Fasting levels of homocysteine were taken from both groups. Allowances were made for age, sex, hypertension, cholesterol, smoking, creatinine and nutritional measures. Individuals were also screened for variations in a particular gene called MTHRF that prevents folate from being processed properly by the body.

Investigators found a strong association between a 50 to 70 percent increase in homocysteine levels in the blood and Alzheimer's disease, stroke and vascular dementia, according to the study published in the journal Stroke: Journal of the American Heart Association.

"We report that moderately high plasma levels of homocysteine are associated with stroke, vascular dementia and Alzheimer's disease," concluded the researchers. "This is not due to vascular risk factors, nutritional status or MTHFR genotype."

Further studies are needed to test the influence of vitamin B and folate on the risk of these conditions.

Other sources: Stroke