Published on: August 29, 2012
by Fiona Macrae for Daily News:
Gorging on junk food may not just make you fat – it could also give you dementia. Evidence is growing that a bad diet triggers Alzheimer’s by poisoning the brain.
With studies on animals strongly implicating the hormone insulin in the process, some believe Alzheimer’s to be another version of diabetes. Bizarre as the claim may seem, confirming the link could speed the search for desperately needed new treatments for Alzheimer’s, which, along with other forms of dementia, affects more than 800,000 Britons.
Bad diets are already linked to dementia, through high blood pressure and cholesterol interrupting blood supply to the brain. But the latest theory points to high levels of fatty and sugary food damaging the brain by interrupting its supply of insulin.
In type 2 diabetes, the most common form of the condition, unhealthy foods lead to cells in the body becoming resistant to the insulin they need to convert sugar into energy. This week’s New Scientist magazine says something similar may be happening in Alzheimer’s, with a bad diet preventing brain cells from responding properly to insulin.
Insulin is needed to regulate brain chemicals key to memory and learning, to make and strengthen connections between brain cells and to maintain the blood vessels that supply the brain with blood and oxygen.
In tests, rats given a chemical that stopped their brains from being able to use insulin developed Alzheimer’s symptoms. Suzanne de la Monte, of Brown University in the U.S., said: ‘They were demented. They couldn’t learn or remember.’
And triggering diabetes created Alzheimer’s-like changes in the brains of rabbits, including the development of the sticky beta amyloid plaques that clog up the brains of human patients.
Evidence that resistance to insulin is key also comes from a University of Pennsylvania study of brain tissue taken from cadavers.
Brain tissue from people who had not had Alzheimer’s seemed to spring back to life when it was bathed in insulin. But brain cells from Alzheimer’s patients barely reacted at all.
And when researchers fed healthy men and women fatty, sugary foods for a month levels of insulin and beta amyloid rose.
New Scientist says: ‘If they are right – and a growing body of evidence suggests they might be – the implications are deeply troubling. Since calorific foods are known to impair our body’s response to insulin, we may be unwittingly poisoning our brains every time we chow down on burgers and fries.’
It adds that sufferers of type 2 diabetes – the form that usually occurs in overweight, middle-aged adults – may be particularly vulnerable to diabetes of the brain. With rates of diabetes soaring, dementia could be on course to reach ‘epidemic’ proportions.
But there is some hope. Early trials of an insulin nasal spray have had promising results and diabetes drugs could make the brain more sensitive to insulin or help break up the poisonous plaques.
The Alzheimer’s Society’s director of research, Professor Clive Ballard, said: ‘One in three people over 65 will develop dementia. Research like this points us in new directions for treatment development.’
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