Abstract: New research shows that, independent of obesity, a high-fat diet for just three days can cause memory loss and brain inflammation in older people. Researchers compared old rats with older rats fed diets at 60% of the calories from fat, and found that only older rats showed cognitive decline.
Changes in metabolism and gut health took several months, but memory impairment quickly manifested in the elderly brain. Findings suggest that diet-related encephalopathy is not driven solely by obesity, but occurs rapidly in an unhealthy diet.
Important Facts:
A high-fat diet for just three days caused memory impairment in older rats. Brain inflammation occurred prior to changes in metabolism and intestinal health. Your rats on the same diet did not experience cognitive decline.
Source: Ohio State University
Eating a diet high in saturated fat may be sufficient to cause memory problems and associated brain inflammation in older people, new research in rats suggests.
Researchers compared how separate groups of young rats are fed a high-fat diet for three days or three months to rapidly change in the brain and the rest of the body when eating an unhealthy diet.
As expected based on previous diabetes and obesity studies, eating fatty foods for three months resulted in dramatic changes in the intestine compared to those consumed normal chow, while high fat for three days did not cause large-scale metabolic or intestinal changes.
However, when it comes to brain changes, the researchers found that only older rats, whether they only had a high-fat diet for three months or three days, were performed poorly on memory tests, showing negative inflammatory changes in the brain.
Ruth Barientos, an investigator at Ohio State’s Institute of Behavioral Medicine, said the results dispel the idea that obesity-driven diet-related inflammation in the aging brain. While most studies on the effects of fat and processed foods on the brain focus on obesity, the effects of unhealthy feeding, independent of obesity, remain largely unexplored.
“Unhealthy diet and obesity are linked, but they are inseparable. We are truly looking directly for the effects of diet on the brain. And Barientos, who is also an associate professor of psychiatry, behavioral health and neuroscience at Ohio’s medical school, said:
“All animals’ body changes occur more slowly and are not necessary to actually cause memory loss and brain changes. You would never have known that brain inflammation is the main cause of high-fat diet-induced memory loss without comparing the two timelines.”
This study was recently published in Journal Immunity & Aging.
Long-standing research in Barientos’ lab suggests that aging leads to long-term “priming” of brain cell spare loss and bouncing brain inflammatory profiles, and that an unhealthy diet can exacerbate brain problems in older people.
Fats account for 60% of the calories in high-fat diets used in studies, which could represent a range of common fast food options. For example, nutritional data shows that McDonald’s Double Smoky BLT Quarter Pounder cheese or Burger King Double Whopper cheese and calories account for about 60% of the cheese and calories.
After animals took a high-fat diet for three days or three months, the researchers performed the tests by assessing two types of memory problems common in older people with dementia based on separate regions of the brain: ced fair memories derived from contextual memory mediated by the hippocampus (the main memory center of the brain);
Compared to animals eating butterflies and young mice on a high-fat diet, aged rats showed behavior indicating that both types of memory were damaged after a 3-day fat diet.
The researchers also saw changes in levels of protein ranges called cytokines in the brains of aged rats after three days of fatty food. This showed a dysregulated inflammatory response. Three months after taking the high-fat diet, some of the cytokine levels changed but remained dysregulated, and cognitive problems persisted on behavioral tests.
“Deviation from baseline inflammatory markers is a negative response and has been shown to impair learning and memory function,” Varientos said.
Compared to rats eating normal chow, older animals gained more weight and showed signs of metabolic dysfunction – poor insulin and glycemic control, inflammatory proteins in fat (fat) tissues, and altered gut microbiota three months after a high-fat diet. The memories, behaviors and brain tissues of young mice were not affected by fatty foods.
“These diets lead to obesity-related changes in both young and old animals, but younger animals appear to be resilient due to the effects of high-fat diets on memory, likely due to their ability to activate compensatory anti-inflammatory responses that aging animals lack,” said Barientos.
“Also, because inflammation of glucose, insulin and fat has led to an increase in both old animals and old animals, there is no way to distinguish between what is happening in the body that is causing memory loss only in old animals. What’s important for memory responses is what’s happening in the brain.”
Funding: This work was supported by grants from the National Institute of Aging.
Co-authors include Michael Butler, Stephanie Muscat, Bridget Gonzalez Ormo, Sabrina Mackie Alfonso, Nashari Massa, Brian Alvarez, Jade Blackwell, Menaz Betts and James DeMarsh of Ohio. Maria Elisa Caetano Silva, Alicity Schresta, Robert McCusker and Jacob Allen of the University of Illinois at Urbana-Champaign.
About this diet and memory research news
Author: Emily Caldwell
Source: Ohio State University
Contact: Emily Caldwell – Ohio State University
Image: Image credited to Neuroscience News
Original research: Open access.
“Obesity-related memory disorders and neuroinflammation precede widespread peripheral perturbations in older rats,” Ruth Barrientos et al. Immunity and aging
Abstract
Obesity-related memory impairment and neuroinflammation precedes widespread perturbation in older rats
background
Obesity and the metabolic syndrome are major public health concerns associated with cognitive decline with aging. Previous studies from our lab demonstrate that short-term high-fat diet (HFD) rapidly impairs memory function via neuroinflammatory mechanisms. However, the extent to which these rapid inflammatory changes are inherent in the brain is unknown.
Furthermore, although deviations in gut microbiome composition are associated with obesity and cognitive impairment, it is less clear how diet and aging interact to affect the gut microbiome, or how quickly these changes occur.
Therefore, our study investigated the effects of HFD after two different periods of consumption: 3 months (modeling diet-induced obesity) or 3 days (to detect rapid changes occurring in HFD), memory function, anxiety-like behavior, central and peripheral inflammation, and gut microbial profiles in aged rats.
result
Our data show that both short- and long-term HFD consumption impairs memory function and increases increased anxiety-like behavior, rather than aging but younger adults. These behavioral changes were accompanied by anti-inflammatory cytokine dysregulation in the hippocampus and amygdala of aged HFD-fed rats at both time points.
However, changes in fasting glucose, insulin, and inflammation in peripheral tissues such as the distal colon and visceral adipose tissue were increased only in young and aged rats, but not short-term and not short-term HFD consumption.
Furthermore, subtle HFD-induced changes in the gut microbiota occurred rapidly, but robust age-specific effects were present only after long-term HFD consumption.
Conclusion
Overall, these data suggest that HFD-induced neuroinflammation, memory impairment, and anxiety-like behaviors in aging develop apart from peripheral features of diet-induced obesity.
