Browning meat in the oven, grill or frying pan produces chemicals which may increase the risk of developing dementia, US researchers suggest.
Advanced glycation end (AGE) products have been linked to diseases such as type-2 diabetes.
Mice fed a high-AGEs diet had a build-up of dangerous proteins in the brain and impaired cognitive function.
Experts said the results were "compelling" but did not provide "definitive answers".
AGEs are formed when proteins or fats react with sugar. This can happen naturally and during the cooking process.
Researchers at the Icahn school of medicine at Mount Sinai, in New York, tested the effect of AGEs on mice and people.
The animal experiments, published in Proceedings of the National Academy of Sciences, showed that a diet rich in AGEs affects the chemistry of the brain.
It leads to a build-up of defective beta amyloid protein - a hallmark of Alzheimer's disease. The mice eating a low-AGEs diet were able to prevent the production of damaged amyloid.
The mice performed less well in physical and thinking tasks after their AGEs-rich diet.
A short-term analysis of people over 60 suggested a link between high levels of AGEs in the blood and cognitive decline.
"This paper adds to the body of evidence suggesting that using preventative strategies might reduce the prevalence of Alzheimer's disease and other dementias in society and that could have very positive impact on us all."