A diet high in fat and calories may raise the risk of Alzheimer's disease in people who are genetically susceptible to the disease, researchers have found.

Researchers found people over 65 who ate the most and carried a gene associated with Alzheimer's were 2.3 times more likely to develop the disease than those who ate the least.

"Those who take cholesterol-lowering drugs are protected to a certain extent against Alzheimer's," said Poirier. "So it's sort of a combination of factors. Completely independent studies are converging with this story (to show) cholesterol is central to the Alzheimer disease biology."

Dr. Jude Poirier

Free radicals may play a role

Researchers suspect our bodies produce more toxins called free radicals from processing higher calorie, high fat diets. Free radicals may hurt cells and increase the damage from beta amyloids, the glue-like particles found in the brains of people with Alzheimer's, Luchsinger said.

The findings may support a controversial theory that suggests people who eat less may live longer. Lower calorie diets have been associated with longer life spans in mice and rats.

"Reduced calorie intake can increase the brain's capacity for plasticity and repair in neurodegenerative disorders, including AD," the researchers wrote in Thursday's issue of The Archives of Neurology.

Luchsinger cautioned he wouldn't make dietary recommendations for people trying to avoid Alzheimer's disease, and researchers don't know how calories or fat might increase the risk in those who carry the Alzheimer gene.

Lola Noel of the Quebec Federation of Alzheimer Societies agreed more studies are needed to confirm the findings.