Yale Graduate School of Arts and Sciences

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Understanding Food Addiction

Working at Yale’s Rudd Center for Obesity Research and Policy, Ashley Gearhardt (Psychology) has found that food addiction and substance dependence trigger similar brain activity.

Ashley’s work strengthens the hypothesis that some people are physically addicted to foods high in added fat and sugar. Her research has been published in the Archives of General Psychiatry and is part of her dissertation.

To identify individuals with symptoms of food addiction, Ashley devised a 25-point questionnaire based on a similar questionnaire that is used to diagnose substance dependence. According to the Yale Food Addiction Scale, as the instrument is called, some of the people who participated in the study showed signs of being addicted to food regardless of their body type. Whether lean, obese, or in between, their weight did not correlate to their likelihood of having food addiction.

Previous research had identified similar patterns of brain activity in obese and substance-dependent people, which has led to the theory that some people may be addicted to high-calorie foods. However, no previous studies explored whether lean individuals who exhibit symptoms of addictive eating behavior have neural responses similar to those of drug addicts.

Ashley and her team conducted the experiment at the University of Oregon using functional MRI to record brain activity as the 48 test subjects were shown images of a chocolate milkshake and of a clear, flavorless liquid that served as a control. MRI images were also recorded while the participants actually tasted those drinks. The milkshake, she reports from personal experience, “is extremely tasty.”

An fMRI machine uses the magnetic properties of blood to see what brain regions appear most active. “It is similar to working out,” she explains. “When you are working a certain muscle, blood rushes to that area. The brain appears to work the same way, and we can track what brain regions are receiving the most blood.” Ashley notes that her first study using fMRI “was a learning experience,” one made easier by collaborating with the Oregon Research Institute’s Eric Stice and Sonja Yokum, experts in understanding brain responses to food cues and consumption.

Ashley found that both thin and overweight participants who had higher food addiction scores showed different brain activity patterns than those with lower scores. In response to the anticipated receipt of food, participants with higher food addiction scores showed greater activity in parts of the brain responsible for cravings and the motivation to eat, but less activity in the regions responsible for inhibiting urges during consumption. Like drug addicts, people with food addiction may struggle with increased cravings and stronger urges to eat in response to food cues and may feel more out-of-control when eating something delicious.

“The findings of this study support the theory that compulsive eating may be driven in part by an enhanced anticipation of food rewards,” Ashley says. “Addicted individuals are more likely to be physiologically, psychologically, and behaviorally reactive to triggers such as advertising. The possibility that food-related cues may trigger pathological properties is of special concern in the current food environment, where highly palatable foods are constantly available and heavily marketed.” In follow up to the milkshake experiment, she is now investigating the neural correlates of food advertising and its association with food addiction.

Kelly Brownell and Will Corbin advise Ashley’s work on food addiction, and Teresa Treat advises her study of attentional bias and eating. Ashley earned her undergraduate degree from the University of Michigan. She is currently undertaking a clinical predoctoral internship in Ann Arbor.