The new research was presented at the 34th Society for Neuroscience annual meeting in San Diego.
Reducing the amount of dietary fat and empty calories may improve memory and help reduce the negative effects of stress and aging on thinking and learning, recent animal studies suggest. Other work shows that diets high in fats and carbohydrates may worsen cognitive losses due to sleep apnea in those prone to the condition.
Nearly two-thirds of adults in the United States are overweight, and 30.5 percent are obese, according to data from a recent National Health and Nutrition Examination Survey.
"We are in the midst of an obesity epidemic in the United States," says Barry Levin, MD, of the VA Medical Center in East Orange, N.J. "These new studies show that diets high in fat are a risk factor for not only heart disease, hypertension, and diabetes, but for cognitive decline as well."
Veerendra Kumar Madala Halagappa, PhD, and Mark Mattson, PhD, of the National Institute on Aging studied how a diet high in fat and sugar affected learning and memory in mice.
Young adult male mice were divided into four groups by diet: normal (control) diet, high-saturated-fat diet, high-sugar diet, and diet high in saturated fats and sugar. They were kept on the diet for four months. Mice on the high-fat diet or the diet high in both fats and sugar had gained significantly more weight than those on the control and high sugar diets after the four months.
To test their learning and memory, the mice then completed a maze task. Halagappa found that the mice on the high-fat and high-fat, high-sugar diets could not learn and remember the maze as well as those on the other diets.