Can the nation’s obesity epidemic be behind the rising rates of learning disabilities and attention deficit hyperactivity disorders? A new University of Illinois study suggests the answer may be “yes,” and identified a possible link between high-fat diets and such childhood brain-based mental health conditions.
The findings, published online in the journal Psychoneuroendocrinology, are based on laboratory studies of mice. But lead researcher Gregory Freund, a professor in the University’s College of Medicine and a nutritional science specialist, said they have important implications for people.
“We found that a high-fat diet rapidly affected dopamine metabolism in the brains of juvenile mice, triggering anxious behaviors and learning deficiencies,” said Freund. “Interestingly, when [Ritalin] was administered, the learning and memory problems went away."
Freund said that altered dopamine signaling in the brain is common in people with ADHD and individuals who are overweight or obese.
He said the study was triggered by the recent upsurge in both child obesity and adverse childhood psychological conditions, including impulsivity, depression, and ADHD. His team examined the short-term effects of a high-fat diet (60 percent calories from fat) versus a low-fat diet (10 percent) on the behavior of two groups of mice.
“After only one week of the high-fat diet, even before we were able to see any weight gain, the behavior of the mice in the first group began to change,” he said.
The mice placed on the high-fat diet demonstrated symptoms of anxiety and developed learning and memory deficits, including a decreased ability to negotiate a maze or recognize objects. The researchers also found that a high-fat diet initiates chemical responses in the brain that are similar to those seen in addiction, with dopamine, the chemical important to the addict's pleasurable experiences, increasing in the brain.
Switching mice from a high-fat to a low-fat diet normalized their behavior in one week, Freund noted.
"Although the mice grow out of these anxious behaviors and learning deficiencies, the study suggests to me that a high-fat diet could trigger anxiety and memory disorders in a child who is genetically or environmentally susceptible to them," he added.
The study was funded, in part, by the National Institutes of Health.
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