Keto diet improves memory, coordination in rat models

By Staff 9 Min Read

  • The number of people with Alzheimer’s disease and other types of dementia is expected to triple by 2050.
  • Cognitive behavior, motor function, and blood lipid (fats) levels can all play a role in Alzheimer’s disease development.
  • Researchers at the University of California, Davis, found that following a ketogenic (keto) diet may significantly decrease blood levels of tau protein in a rat model of Alzheimer’s disease.
  • The keto diet also helped decrease blood lipid levels in the animal model.

A new study in female rat models, conducted by researchers at the University of California, Davis, has found that following the ketogenic — or keto diet, for short — may significantly decrease blood levels of tau protein, which has been found to accumulate in the brains of people with Alzheimer’s disease.

The study, recently published in the journal Aging, also found that animals in the Alzheimer’s disease model following the keto diet also experienced a decrease in their blood lipid (fats) levels.

Past studies have linked high levels of cholesterol — a type of blood lipid — to an increased risk for this type of dementia.

With the number of people around the world with Alzheimer’s disease and other types of dementia expected to triple by 2050, researchers are continuing to find new ways of preventing and treating Alzheimer’s disease.

In this study, scientists focused on finding ways to improve cognitive behavior, motor function, and blood lipids, which can all play a role in Alzheimer’s disease development.

“Cognitive deficits are a hallmark of Alzheimer’s disease and decreases in motor function occur as the disease progresses,” Jennifer Rutkowsky, PhD, an associate project scientist in the Department of Molecular Biosciences in the School of Veterinary Medicine at the University of California, Davis, and lead author of this study explained to Medical News Today.

“There is also evidence that elevated levels of blood fatty acids and cholesterol are associated with the development of Alzheimer’s disease pathology,” she told us.

“As the population of elderly people in the United States expands, so will the incidence of Alzheimer’s disease,” Rutkowsky continued. “Therefore, there is a need to identify viable strategies that can improve cognitive behavior, motor function, and blood lipids as a way to increase the length of healthy life in humans.”

According to researchers, past studies have suggested that the keto diet may help improve memory in mouse models of Alzheimer’s disease.

For this study, Rutkowsky and her team focused on examining which type of keto diet — continuous or intermittent — may have an impact.

“For this study, a continuous ketogenic diet describes the feeding of a ketogenic diet every day in both the morning and evening meals,” Rutkowsky detailed. “With the intermittent ketogenic diet, the animals were fed the control meal each morning and the ketogenic meal each evening.”

“The continuous ketogenic diet was designed to produce a continuous elevation in blood ketone levels while the intermittent ketogenic diet was designed to produce increases in blood ketone levels for only part of each day,” she continued.

“The key issue is that compliance with the continuous ketogenic diet can be difficult whereas it is easier to comply with an approach that induces only intermittent ketosis,” Rutkowsky told us.

The scientists used a TgF344-AD rat model, or transgenic rat model, of Alzheimer’s disease for this study.

These rats are bred with specific genetic mutations associated with Alzheimer’s disease, resulting in the pathological changes normally seen in humans with the condition.

“Mouse models have primarily been used in previous studies investigating the influence of long-term consumption of ketogenic diets on aging and the potential benefits of these diets in models of Alzheimer’s disease,” Rutkowsky said.

“The TgF344-AD rat produces changes in a wide range of Alzheimer’s disease-related pathologies, and the goal of our study was to determine if potential benefits of a ketogenic diet occur in a rat model as a step toward determining if there are general changes with this diet that occur across species,” she explained.

“This is a common approach in science to confirm findings in multiple species as this increases confidence that findings can be extrapolated, or translated, from a rodent model to humans,” Rutkowsky added.

Animals in the rat model were placed on either a continuous or intermittent keto diet or a control diet at six months old.

Researchers found that by 12 months old, rats on both types of keto diet did not show any improved spatial learning memory or motor coordination compared to those in the control group.

However, rats on both an intermittent and continuous ketogenic diet experienced decreased cholesterol levels. Additionally, scientists found the keto diet significantly decreased blood levels of tau protein in female rats.

“Our study did show that a ketogenic diet dramatically decreased blood lipid levels and significantly decreased blood tau levels in female mice, suggesting that in individuals with genetic susceptibility for late-onset Alzheimer’s disease, changes in diet may be beneficial in slowing or mitigating some aspects of disease onset/progression. Further, the ketogenic diet produced changes that may improve some aspects of health in these animals.”

– Jennifer Rutkowsky, PhD

“The next step is to determine if the ketogenic diet significantly alters markers of pathology and cellular processes that contribute to disease progression,” Rutkowsky continued.

“Translation of the present study to humans would involve consumption of a ketogenic diet, or possibly a ketone supplement, prior to the development of major disease symptoms. This would require motivated people who would commit to a diet change for a significant portion of their lives. Therefore, it is important to determine if the diet produces sufficient changes to warrant long-term diet studies in humans,” she cautioned.

MNT also spoke with Monique Richard, MS, RDN, LDN, a registered dietitian nutritionist and owner of Nutrition-In-Sight, about this study.

Richard stressed that the keto diet, while an effective, well-researched therapeutic diet for epilepsy and other specific medical health conditions when being closely monitored by a registered dietitian nutritionist and respective healthcare team, is not for everyone.

“For most individuals, a ketogenic diet is difficult to follow, is not sustainable long-term, and could have negative consequences,” she explained.

“In clinical practice, I have observed individuals’ goals such as a decrease in weight or blood glucose levels be positively affected almost immediately following a ketogenic diet — they either self-prescribed or followed social media to implement a keto diet,” said Richard.

“However, after a ‘honeymoon phase’ of 8-12 weeks, many individuals’ lipid profiles and liver enzymes dramatically increased while their digestive health — bowel movements, gastrointestinal issues — cognition, and satisfaction or pleasure with eating were adversely affected,” she warned. “In addition, both their macro- and micronutrient needs are commonly not consistently being met which may cause other symptoms or exacerbate other issues.”

Richard said it is also important to remember that brain health is not only supported by proper nutrition and a standard lipid profile does not tell the whole story of internal health.

“It would be interesting to see if there was any correlation between those following a ketogenic diet or modified ketogenic diet for five to 10 years or more and increased risk for colon cancer or digestive impairment including integrity of the gallbladder, liver, and gut lining,” she added.

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