A new study backs up previous indicators showing that excessive intake of aluminum can increase the risk of dementia among the elderly.

A group of scientists in France examined the link between daily exposure to aluminum and silica in drinking water and the risk of cognitive decline, including forms of dementia such as Alzheimer's disease.

The group studied people 65 years of age or older over a period of 15 years and found that seniors who consumed a large amount of aluminum were twice as prone to dementia.

In the case of silica by contrast, for every 10-mg increase in consumption, the possibility of developing dementia dropped by 11 percent.