Sugar seems to be a culprit in Alzheimer's.
'Alzheimer's disease driven by diet': Scientists suggest sugar cravings fuel dementia - Study Finds
Fructose restricts blood flow to the brain’s cerebral cortex, which is involved in self-control, as well as the hippocampus and thalamus. Simultaneously, blood flow increases around the visual cortex, a region associated with food reward. All of this together helps stimulate the foraging response.
“We believe that initially the fructose-dependent reduction in cerebral metabolism in these regions was reversible and meant to be beneficial,” Prof. Johnson adds. “But chronic and persistent reduction in cerebral metabolism driven by recurrent fructose metabolism leads to progressive brain atrophy and neuron loss with all of the features of AD.”
The human ‘survival switch’ results in overeating today
Prof. Johnson theorizes that this survival response, which he calls a “survival switch,” helped ancient humans survive periods of extreme scarcity. Today, however, that survival switch is still on, so to speak, in a time of relative abundance. This promotes the overeating of high fat, sugary and salty foods resulting in excess fructose production.
Fructose created in the brain can promote inflammation and eventual Alzheimer’s disease, the study concludes. For example, animals consuming fructose display memory lapses, a loss in the ability to navigate a maze, and neuronal inflammation.
“A study found that if you keep laboratory rats on fructose long enough they get tau and amyloid beta proteins in the brain, the same proteins seen in Alzheimer’s disease,” Prof. Johnson comments. “You can find high fructose levels in the brains of people with Alzheimer’s as well.”