UCSD. US: A new study
led by researchers at University of California, San Diego School of
Medicine finds that the brains of obese children literally light up
differently when tasting sugar.
Published online in International Journal of Obesity, the
study does not show a causal relationship between sugar hypersensitivity
and overeating but it does support 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.
“The take-home message is that obese children, compared to healthy
weight children, have enhanced responses in their brain to sugar,” said
first author Kerri Boutelle, PhD, professor in the Department of
Psychiatry and founder of the university’s Center for Health Eating and
Activity Research (CHEAR).
“That we can detect these brain differences in children as young as
eight years old is the most remarkable and clinically significant part
of the study,” she said.
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.
Ten of the children were obese and 13 had healthy weights, as
classified by their body mass indices. All had been pre-screened for
factors that could confound the results. For example, they were all
right-handed and none suffered from psychiatric disorders, such as
anxiety or ADHD. They also all liked the taste of sucrose.
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.
“Any obesity expert will tell you that losing weight is hard and that
the battle has to be won on the prevention side,” said Boutelle, who is
also a clinical psychologist. “The study is a wake-up call that
prevention has to start very early because some children may be born
with a hypersensitivity to food rewards or they may be able to learn a
relationship between food and feeling better faster than other
children.”
According to studies, children who are obese have an 80 to 90 percent
chance of growing up to become obese adults. Currently about one in
three children in the U.S. is overweight or obese.
To learn more CHEAR and its weight management programs for children, call 855-827-3498 or email chear@ucsd.edu
Co-authors include Christina Wierenga, UC San Diego and Veterans
Affairs San Diego Healthcare System; Amanda Bischoff-Grethe, Andrew
James Melrose and Emily Grenesko-Stevens, UC San Diego; and Martin
Paulus, Laureate Institute for Brain Research, Tulsa, OK.
Funding for the study was provided, in part, by National Institutes
of Health (grants R01DK094475, R01 DK075861, K02HL112042, MH046001,
MH042984, MH066122, MH001894 and MH092793).