University of Illinois researchers have determined a likely link between ADHD and high-fat diets
The prevalence of childhood obesity has risen dramatically and concurring with this upsurge is a growth in adverse childhood psychological conditions including impulsivity, depression, anxiety and attention deficit/hyperactive disorder (ADHD). Due to confounds that exist when determining causality of childhood behavioral perturbations, controversy remains as to whether overnutrition and/or childhood obesity is important, according to the studies summary.
To find out the answer, researchers from the University of Illinois examined juvenile mice to determine if biobehaviors were impacted by a short-term feeding (1–3 wks) of a high-fat diet (HFD). The team looked at the effects between high-fat diet (60% of calories from fat) compared to a low-fat diet (10% of calories from fat) on the behavior of two groups of four-week-old mice.
Dr. Gregory Freund, MD, professor of pathology and head, department of animal sciences, U of I, noted a typical Western diet contains 35 to 45% fat.
"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, said Dr. Freund.
Mouse burrowing and spontaneous wheel running were increased while mouse exploration of the open quadrants of a zero maze, perfect alternations in a Y-maze and recognition of a novel object were impaired.
When mice were switched from a high-fat diet to a low-fat diet, the memory of the mice was restored within one week.
The mice that had continued the high-fat impaired object recognition remained three weeks after the onset of symptoms. However, Dr. Freund is aware from other studies that brain biochemistry normalizes after 10 weeks as the body appears to compensate for the diet. At that time brain dopamine has returned to normal, and mice have become obese and developed diabetes.
Dr. Freund states "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.”
Due to the fact the animals adjust to a high-fat diet, the researchers suggest that abruptly removing fat from the diet might negatively affect anxiety, learning, and memory.
The researchers had expected that the high-fat diet would stimulate inflammation, which is associated with obesity, but they saw no evidence of an inflammatory response in the brain after one or three weeks on the high-fat regimen.
Instead, they saw evidence that a high-fat diet initiates chemical responses that are similar to the ones seen in addiction, with dopamine, the chemical important to the addict's pleasurable experiences, increasing in the brain.
The researchers write “Over nutrition due to fats may be central to childhood psychological perturbations such as anxiety and ADHD.”
In closing Dr. Freund said "We found that a high-fat diet rapidly affected dopamine metabolism in the brains of juvenile mice, triggering anxious behaviors and learning deficiencies. Interestingly, when methylphenidate (Ritalin) was administered, the learning and memory problems went away.”
The research was published in Psychoneuroendocrinology and is available pre-publication online at Science Direct.
Different studies have suggested there is a link between obesity and ADHD.
According to ADHD Statistics 8.4% of children aged 3 to 17 years have been diagnosed with ADHD.
Causes of ADHD can be found online at PsychCentral website.