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Psychiatry Newsletter - Brain Circuity and Obesity Risk

Hopkins BrainWise Spring 2014

Brain Circuity and Obesity Risk

Date: May 1, 2014

Susan Carnell
Susan Carnell titled her recently published study “Fat brains, greedy genes, and parent power: a biobehavioral risk model of child and adult obesity.”

In an environment laden with high-calorie, palatable foods, why do some people become obese while others manage to stay lean? Psychologist Susan Carnell has been using brain imaging and other research tools to tease out risk factors for obesity in childhood.

“We know that individuals differ in appetite-related behavioral traits like responsiveness to food cues,” she explains. “These traits show up very early in life, are influenced by biological factors such as genetics, and interact with the environment, affecting our eating behavior and likelihood of becoming obese.”

With funding from the National Institute of Diabetes and Digestive and Kidney Diseases, Carnell plans to investigate the neural underpinnings of obesity and familial/genetic obesity risk in adolescents. To do so, she’ll image the brains of about 90 adolescents—a mix of obese teenagers, lean teens with obese mothers, and lean teens with lean mothers—while they perform food-related tasks custom-designed to tap into reward and self-regulation circuits. She’ll also study saliva DNA and assess families’ food and physical activity habits. There could be resiliency as well as risk factors at play, she says. For example, maybe lean adolescents with obese mothers offset their heightened obesity risk by exercising more.

A companion project in 8- to 13-year-olds will see if obese children and those with raised familial obesity risk also demonstrate altered brain responses. In both projects, Carnell hopes to investigate not only the neural circuitry relating to appetite for food, but also the circuits underlying related issues like general impulsivity and self-control, which may be altered in obesity as well as other common disorders, such as ADHD.

The studies build on her previous work, which showed that lean adolescents with obese or overweight mothers showed relatively less activation in brain circuits associated with self-regulation, including multiple structures within the frontal and cingulate cortices, than lean teens from lean mothers. Just seeing written words describing high-calorie foods, like frosted cupcake, triggered more wanting in these teens, who also ate relatively more when presented with a smorgasbord of different foods.

Identifying the circuitry underlying obesity risk could highlight biomarkers capable of predicting excessive weight gain before the problem begins, she says, but “even if this proves challenging, a better understanding of neurobehavioral risk factors is certain to inspire novel, biologically informed interventions to prevent or treat obesity.” 

For information: 410-614-0012.