Researchers hone in on the biological mechanisms that underpin the link between diet, diabetes and Alzheimer’s.
It may be common knowledge that high-sugar, high-fat foods (think: fried food, milkshakes, pastries, cakes and cookies) aren’t good for your waistline, but could they also be harming your brain? A new study has found that eating foods high in fat and sugar, along with aging, could increase the risk of Alzheimer’s.
Scientists from Brock University in Ontario, Canada used mice to test whether diet affects the chances of developing Alzheimer’s. For thirteen weeks, they gave one group of mice a diet high in fat and sugar, and another group a normal diet. When they measured the inflammation levels in the hippocampus, the brain’s memory center, and the prefrontal cortex, the area of the brain responsible for decision-making and social behavior, they found that the brains of the mice given the high-fat, high-sugar diet had more inflammation, cellular stress and insulin resistance—which is associated with degenerative brain diseases like Alzheimer’s.
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In the control group, inflammation levels rose, too, which the researchers interpreted as a sign that diet isn’t the only factor at play—aging itself may cause inflammation. But the evidence shows that a poor diet may increase the effects of aging, according to the study authors.
“These results add to our basic understanding of the pathways involved in the early progression of [Alzheimer’s] … and demonstrate the negative effects of a [high-fat, high-sugar] diet on both the prefrontal cortex and hippocampal regions,” the study team wrote.
Both poor diet and obesity have been linked to Alzheimer’s in the past. In a study last year, MRI scans revealed that people who were obese, smoked, had elevated cholesterol levels, high blood pressure or diabetes had more beta-amyloid in their brains, the sticky protein that builds into plaques in the brains of Alzheimer’s patients. Having just one of those risk factors increased the likelihood of elevated amyloid levels by 88 percent; two or more risk factors nearly tripled the likelihood of elevated amyloid. Even amongst those risk factors, obesity stood out—it alone nearly doubled the chances of elevated amyloid in later life.
Sugar, in particular, has been implicated in Alzheimer’s disease. Some scientists even refer to Alzheimer’s as ‘Type 3 diabetes’ because of the difficulty Alzheimer’s brains seem to have in breaking down glucose, the brain’s main source of energy. High levels of blood sugar have been shown to cause memory problems even when they are not at levels that qualify as diabetic and the fluctuation in blood sugar is mild. And of course, Type 2 diabetes itself is a risk factor for dementia, raising the lifetime likelihood of being diagnosed by 75 to 100 percent. Some scientists have even shown that diabetes drugs show promise in treating Alzheimer’s.
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The evidence does start to add up—diets high in sugar and fat are likely bad for both the brain and the body. But while this study corresponds with other evidence that shows diet can affect brain health, it was conducted on mice, not people. More research is needed to see if the same findings hold true in humans.
This study was published in Physiological Reports.