Scientists have discovered that brains of obese children have a different response to sugar.
Researchers at University of California conducted a study, which though didn't show a causal relationship between sugar hypersensitivity and overeating, supported the idea that the growing number of America's obese youth may have a heightened psychological reward response to food.
This elevated sense of food reward- which involves being motivated by food and deriving a good feeling from it- could mean some children have brain circuitries that predispose them to crave more sugar throughout life.
First author Kerri Boutelle, PhD, said that they could detect the brain differences in children as young as 8 years old, and it was the most remarkable and clinically significant part of the study.
For the study, the UC San Diego team scanned the brains of 23 children, ranging in age from 8 to 12, while they tasted one-fifth of a teaspoon of water mixed with sucrose (table sugar). The children were directed to swirl the sugar-water mix in the mouth with their eyes closed, while focusing on its taste.
The brain images showed that obese children had heightened activity in the insular cortex and amygdala, regions of the brain involved in perception, emotion, awareness, taste, motivation and reward.
Notably, the obese children did not show any heightened neuronal activity in a third area of the brain- the striatum- that is also part of the response-reward circuitry and whose activity has, in other studies, been associated with obesity in adults.
The striatum, however, does not develop fully until adolescence. The researchers said one of the interesting aspects of the study is that the brain scans may be documenting, for the first time, the early development of the food reward circuitry in pre-adolescents.
According to studies, children who are obese have an 80 to 90 percent chance of growing up to become obese adults.
The study is published online in International Journal of Obesity.