‘Alzheimer’s disease driven by diet’: Scientists suggest sugar cravings fuel dementia

AURORA, Colo. — An ancient human survival instinct still embedded deep within our brains may be driving dementia onset thanks to an unlikely accomplice — fructose, a kind of sugar. Researchers from the University of Colorado Anschutz say this instinctual foraging mechanism, fueled by fructose production in the brain, could provide new clues into both the development and possible treatment of Alzheimer’s disease, the most common form of dementia.

Study authors believe their findings present a unique take on an awful-yet-common disease, which develops due to abnormal accumulations of proteins in the brain, eventually resulting in the deterioration of both memory and cognition.

“We make the case that Alzheimer’s disease is driven by diet,” says the study’s lead author Richard Johnson, MD, professor at the University of Colorado School of Medicine specializing in renal disease and hypertension, in a media release.

What does Alzheimer’s have to do with being hungry?

Prof. Johnson and his team explain that Alzheimer’s may be a harmful adaptation of an evolutionary survival pathway used by animals and our distant ancestors during times of scarcity for centuries.

“A basic tenet of life is to assure enough food, water and oxygen for survival,” study authors explain. “Much attention has focused on the acute survival responses to hypoxia and starvation. However, nature has developed a clever way to protect animals before the crisis actually occurs.”

Starvation was an everyday threat for early humans. So, they developed a survival response that sent them searching for food. However, foraging for food is only effective if metabolism is inhibited in various parts of the brain. Successful food foraging hinges on focus, rapid assessment, impulsivity, exploratory behavior, and risk taking. In other words, it’s helpful to block out whatever gets in the way, like recent memories and attention to time, while out searching for food. Meanwhile, fructose can help dampen these brain centers, facilitating more focus on food gathering.

Moreover, the research team notes that the entire foraging response sets in motion through the metabolism of fructose, regardless of whether the person eats or produces their own fructose. The metabolization of fructose, and its byproduct intracellular uric acid, is essential to both human and animal survival.

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.”

Prof. Johnson also theorizes that the tendency of some Alzheimer’s patients to wander off could be an evolutionary holdover linked to this ancient foraging response. All in all, the study concludes more research is necessary, examining the role of fructose and uric acid metabolism in dementia.

“We suggest that both dietary and pharmacologic trials to reduce fructose exposure or block fructose metabolism should be performed to determine if there is potential benefit in the prevention, management or treatment of this disease,” Prof. Johnson concludes.

The study is published in the American Journal of Clinical Nutrition.

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John Anderer

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  1. I absolutely do not believe this article. My best friend developed serious Alzheimer’s at age 69 and was institutionalized 14 months later. He did not consume deserts of any kind, was a vegan and sugar was not a part of his diet. However, he has smoked pot literally every day of his life since he was about 28. Also, his mom died of Alzheimer’s and his sister developed debilitating Alzheimer’s at age 52 and has been institutionalized for 4 years.

  2. All these studies are wild shots in the dark with zero substance to back them up. No wonder we’ve gotten nowhere on curing this.

    My mom wasn’t a sweets person, ate salads and kept portions moderate. She jazzercised and exercised. She tried not to have too much coffee. She replaced her metal filllings with composite ones. She loved crossword puzzles and card games and reading.

    My dad loved every sweet he could get his hands on, was a raging diabetic, hated exercise, was overweight, drank coffee, loved TV, and had tons of metal fillings.

    Guess who died of Alzheimer’s and who didn’t? Yep. The person who did everything the Alzheimer’s studies told her to do to stave it off. And she went that much faster.

  3. My father in law died of Alzheimer’s. It took 15 years to die. He loved sugar, put two or more spoons of sugar in his coffee, insisted on desert after his evening meal, and ate candy while watching TV. He wasn’t overweight.

  4. Fructose is a sugar found naturally in fruits, fruit juices, some vegetables and honey. It is also found high fructose corn syrup which is what was used to replace sugar when people started to realise that sugar was bad and didn’t wanted it in their processed food.

  5. It’s interesting that this study addressed *Fructose* specifically. We’ve been taught to think 3+ servings a day of fruit or fruit juice is “healthy.”
    It would be interesting to read a similar study about Glucose, Sucrose (a.k.a. table sugar, used in baking cookies and cakes for example), and Lactose (a.k.a. dairy sugar). There has been dementia in my family and it scares me. Thank you for this article.

  6. I have stopped buying ketchup containing “high fructose corn syrup.”

    It’s shocking how many foods in the store contain high fructose corn syrup!

  7. My mother was a baker/cook and obese. She developed diabetes in her 60’s and within a year or so of that diagnosis (and medications), she started demonstrating signs of Dementia. It took almost 15 years for her to pass, but she was less there every day/month/year. Sugar was directly responsible, and her and her caregivers refusal to help her lose weight and modify her diet, relying instead on pills that only masked the progressive issue to kept her alive. Alzheimer’s can be hereditary, but in many cases like Diabetes, it’s self inflicted by life choices. I think there’s other connections as well, like pesticides, GMO flour and refined sugar vs natural honey/molasses/etc.

    1. I’m sure you check for the bogeyman under your bed each night as well you sad paranoid nut case,

  8. Because as always, these “studies” skirt around the REAL problem, which is grains and corn syrup. Replace the word “Fructose” with “Carbs” and then you get the more complete picture.
    Your Vegan friend Tony, was on an almost 100% carb diet. Plenty of hidden sugar in that vegan junk.

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