According to a recent study from the University of Colorado Anschutz Medical Campus, increased fructose intake may be a chief cause of Alzheimer’s.
An ancient human foraging drive, fueled by fructose synthesis in the brain, may provide insights into Alzheimer’s development and potential treatment. The study1, published in The American Journal of Clinical Nutrition, provides a fresh perspective on a fatal condition distinguished by aberrant protein accumulations in the brain that gradually degrade memory and cognition.
The study’s lead author Richard Johnson, MD, a professor at the University of Colorado School of Medicine specializing in renal disease and hypertension, made the case that the diet drives Alzheimer’s. According to Johnson and his team, AD is a detrimental adaptation of a survival route that evolved in animals and our ancient ancestors to help them survive in times of scarcity.
Fructose: A Trigger For The Foraging Survival Response
Early humans had a survival reflex that sent them foraging for food when threatened with the risk of starvation. Yet, foraging is only productive if metabolism is suppressed in different brain regions. Focus, quick judgment, impulsivity, risk-taking, and exploratory behavior are necessary for foraging. It improves by obstructing anything that gets in the way, such as recent memories and time awareness. A type of sugar called fructose aids in calming these areas so that acquiring food can be the main focus.
The researchers discovered that fructose metabolism—whether it was consumed or created by the body—set the entire foraging response in action. It was essential for both humans and animals to metabolize fructose and its byproduct, intracellular uric acid.
The hippocampus, thalamus, and cerebral cortex of the brain that are involved in self-control all experience decreased blood flow as a result of fructose, according to the study’s authors. In the meantime, blood flow across the visual cortex related to food reward increased. Everything triggered the foraging response.
Researchers believed that initially, the fructose-dependent decrease in brain metabolism in these areas was reversible and intended to be advantageous. Yet, recurring fructose metabolism-driven chronic and permanent decline in cerebral metabolism causes progressive brain atrophy and cell death, symptoms of Alzheimer’s.
“Survival Switch” Remained In The “On” Position
Johnson hypothesizes that in an era of relative abundance, the survival reflex, or “survival switch,” that enabled prehistoric people to survive times of scarcity, is currently stuck in the “on” position. This results in excessive consumption of foods high in fat, sugar, and salt, which increases the creation of fructose.
According to the study, fructose generated in the brain may eventually cause inflammation and Alzheimer’s disease. When administered fructose, animals exhibit memory loss, decreased maze navigation skills, and neuroinflammation.
Johnson further stated that laboratory rats fed fructose for an extended period in a study developed the tau and amyloid beta proteins implicated in Alzheimer’s in their brains and that high fructose levels are also present in the brains of Alzheimer’s patients.
Johnson hypothesizes that certain AD patients’ propensity to wander off may be a trace of the primate foraging reflex.
The researchers proposed that both dietary and pharmaceutical trials to minimize fructose consumption or inhibit fructose metabolism be conducted to assess if there is potential benefit in the prevention, management, or treatment of this condition.
- Johnson, R.J., Tolan, D.R., Bredesen, D., Nagel, M., Sánchez-Lozada, L.G., Fini, M., Burtis, S., Lanaspa, M.A. and Perlmutter, D., 2023. Could Alzheimer’s Disease Be a Maladaptation of an Evolutionary Survival Pathway Mediated by Intracerebral Fructose and Uric acid Metabolism?. The American Journal of Clinical Nutrition. https://www.sciencedirect.com/science/article/abs/pii/S0002916523000047.
- Kelly, D. Study Suggests Fructose Could Drive Alzheimer’s Disease. University of Colorado Anschutz Medical Campus. https://news.cuanschutz.edu/news-stories/study-suggests-fructose-could-drive-alzheimers-disease. Published online: 13th Feb, 2013, Accessed: 6th March, 2023.
- Fructose could drive Alzheimer’s disease. Science Daily. https://www.sciencedaily.com/releases/2023/02/230213113345.htm. Published online: 13th Feb, 2013, Accessed: 6th March, 2023.
- Group of Scientists Propose a New Driver of Alzheimer’s Disease: Fructose. Science Alert. https://www.sciencealert.com/group-of-scientists-propose-a-new-driver-of-alzheimers-disease-fructose. Published online: 20th Feb, 2023. Accessed: 6th March, 2023.
- Sugary Foods May Be Driving Alzheimer’s, Study Suggests. Psychiatrist.com. https://www.psychiatrist.com/news/sugary-foods-may-be-driving-alzheimers-study-suggests/. Published online: 20th Feb, 2023. Accessed: 6th March, 2023.