Effects of aluminum and silica in water on Alzheimer's disease

NEW YORK (Reuters Health) - Higher levels of aluminum in drinking water appear to increase people’s risk of developing Alzheimer’s disease, while higher levels of silica appear to reduce that risk, French researchers have found.

“Alzheimer’s disease is a multifactorial disease and aluminum levels in drinking water may play a role in cognitive decline and Alzheimer’s disease,” Dr. Virginie Rondeau told Reuters Health.

Results of some studies suggest that silica may reduce the oral absorption of aluminum or increase the excretion of this metal.

Rondeau and her colleagues at the National Institute of Health and Medical Research in Bordeaux studied elderly subjects over a 15-year period, examining the association between exposure to aluminum or silica in drinking water and the risk of cognitive decline, dementia, and Alzheimer’s disease.

Daily aluminum intake of at least 0.1 milligrams was associated with increased cognitive decline over the course of the study, the team reports in the American Journal of Epidemiology.

The researchers pointed out that subjects with higher daily aluminum intake had a 2.26-fold increased risk of developing dementia. On the other hand, consuming 10 mg of silica per day was associated with an 11% lower risk of developing dementia.

“Further studies are needed to resolve the debate on the association between aluminum or silica in drinking water and neurological diseases and cognitive impairment,” the researchers concluded.

Source of the above article: American Journal of Epidemiology, February 15, 2009.