Just three days of eating a diet high in saturated fat leads to memory problems and related neuroinflammation in older rats, reported a new study published in Immunity and Ageing.
Previous research has demonstrated that a short-term high-fat diet triggers neuroinflammation, which rapidly impairs memory function. Changes in gut microbiome composition have also been linked to obesity and cognitive impairment. Hw diet and aging interact to affect the gut microbiome, however, and how quickly these changes occur, remains unclear.
In the current study, researchers investigated the impact of a high-fat diet after 3 days and 3 months on memory function, anxiety-like behavior, central and peripheral inflammation, and gut microbiome profile in both young and aged adult rats. High-fat diets were defined as diets in which fat constituted 60% of calories.
Ultimately, the researchers found that eating a high-fat diet for three months led to metabolic problems, gut inflammation, and shifts in gut bacteria in all rats compared to those who ate a regular diet. Eating a high-fat diet for just three days, however, was not linked to any major metabolic or gut changes.
Meanwhile, eating a high-fat diet for both 3 days and 3 months impaired memory function and increased anxiety-like behavior in aged, but not young rats. These changes coincided with pro- and anti-inflammatory cytokine dysregulation in the hippocampus and amygdala at both time points among aged rats fed a high-fat diet.
"Changes in the body in all animals are happening more slowly and aren't actually necessary to cause the memory impairments and changes in the brain. We never would have known that brain inflammation is the primary cause of high-fat diet-induced memory impairments without comparing the two timelines,” said senior author of the study, Ruth Barrientos, associate professor of psychiatry and behavioral health and neuroscience at The Ohio State University College of Medicine.
Sources: Science Daily, Immunity and Ageing