Onion rings can cause dementia.
Onion rings contribute to brain decline
Experts have found that food made using large amounts of cooking oil contains brain-damaging impurities that can contribute to the degenerative disease.
Rats that were fed a diet high in reused oils showed more signs of body inflammation, which is thought to be associated with the acceleration of cognitive decline.
Boffins also spotted more signs of brain damage in the rodents fed diets high in reheated oils when compared to a control group.
The experts also studied the rats' brains under a microscope and found that those who ate the reheated oils showed damage patterns indicative of dementia.
Scientists from the University of Chicago said: "Deep-frying at high temperatures has been linked with several metabolic disorders.
"To our knowledge, we are the first to report that long-term deep fried oil supplementation increases neurodegeneration."