Is obesity triggered by 'different' brain activity in kids?
The small study found that food smells
activated the parts of their
brains related to impulsive
behaviour and obsessive-compulsive
disorder, which is characterised by
recurrent thoughts and repetitive
behaviours. This did not occur in
children of a normal, healthy weight,
researchers reported.
Impulsivity problem
The findings suggest that children with
obesity are not able to stop eating,
said study author Dr Pilar Dies-Suarez,
head of radiology at the Federico
Gomez Children's Hospital of Mexico in
Mexico City. "Thus, treatment of
obesity must focus on the impulsivity
problem," she said.
But researchers only saw an association
between impulsive brain reactions and
children's weight. It's not conclusive
which one caused the other.
The findings were to be presented at
the Radiological Society of North
America's annual meeting in Chicago.
The researchers used two types of
MRI to compared brain imaging results
from 30 children, ages 6 to 10. During
the MRI, the children smelled
chocolate, onion and a non-food smell
of diluted acetone, the active
ingredient in nail polish remover.
Half the children had a body mass index
(BMI) between 19 and 24, considered
to be a healthy or normal weight, and
half had a BMI over 30, considered
obese.
When the children with obesity
smelled the chocolate or onion, the
researchers saw activity in the part of
their brain involved in impulsive
decisions but did not see activity in the
part of the brain that controls the
impulse to eat, Dies-Suarez said. When
the children with normal BMI smelled
food, the researchers saw activity in
parts of the brain related to regulating
pleasure, planning and emotional
processing or memory.
Different wiring
The brain responses in children with
obesity were also much greater when
they smelled the chocolate and the
onion compared to the responses in
the normal-weight kids. When the
obese children smelled the acetone,
the active parts of their brain were
related to memories and risk
assessment
"This probably shows the brain
processing of a smell which is not that
usual," possibly trying to determine
whether it's a safe food, Dies-Suarez
said. "In contrast, the normal-weight
volunteers seemed to be uninterested
in this stimulus."
The results point out why it's
important to find solutions for people
with obesity instead of blaming them
for the condition, said Dr Mitchell
Roslin, chief of obesity surgery at Lenox
Hill Hospital in New York City.
"This study shows that children who are
obese have different wiring in their
brain," Roslin said. "The results should
make people realise that obesity is not
caused by lack of willpower. Instead,
there are biological differences that
contribute to caloric imbalance."
Obesity treatments should be
evidence-based and insurance coverage
should be mandatory, said Roslin, who
was not involved with the study.
"Obesity is still a condition for which
we blame the afflicted," Roslin said.
"There is little compassion, and
because of our preconceived notions,
coverage for effective treatment is
frequently not available."
The study is small, however, and it
leaves open a number of questions,
said Dr Peter LePort, medical director
of Memorial Care Centre for Obesity at
Orange Coast Memorial Medical Centre
in Fountain Valley, California.
Emotional distress
"This study does not provide evidence
that children are incapable of
controlling food cravings," LePort said.
"What is not clear is how the parents
fed these children to get them to a
BMI over 30."
The study would need to be done with
newborns, comparing the brain
responses of infants when they
consume their mother's milk, and then
following the children to see which
ones become obese, LePort said.
"I have doubts that this effect is inborn
except in rare cases," LePort said,
explaining that the rapid increase in
obesity in the population is occurring
too quickly for evolution to be playing a
role. One possible problem is that
children may be learning from adults to
soothe themselves with food during
emotional distress.
"Infants and children need a correct
model on which to learn how to
function," LePort said.
Data and conclusions presented at
meetings are usually considered
preliminary until published in a peer-
reviewed medical journal.
