For Food Junkies, Brains React to Milkshakes Like Drugs
The brains of food addicts show the same reaction when they anticipate eating as drug addicts show when they anticipate using. Surprisingly, these food addicts, who can't always control their eating habits, aren't fatter than nonaddicts.
"These findings support the theory that compulsive food consumption may be driven in part by an enhanced anticipation of the rewarding properties of food," the researchers write online today (April 4) in the journal Archives of General Psychology. "Similarly, addicted individuals are more likely to be physiologically, psychologically and behaviorally reactive to substance-related cues."
The brains of people addicted to either to food or drugs have a higher release of dopamine (a happiness-inducing brain chemical) in a part of the brain called the mesolimbic system. This brain area is in charge of the reward reinforcement process, which is responsible for the pleasurable feelings we get from things like food and sex, keeping us coming back for more.
Addictive drugs increase release of dopamine in these pathways, creating this feeling of reward and increasing motivation to do more. This causes addiction and dependence. Researchers can see this pathway lighting up in addicts when they are offered their drug of choice during a brain scan.
To study how these brain changes relate to food addiction, the researchers, led by Ashley Gearhardt of Yale University, studied a group of young women with an average age of about 21 and ranging from lean to obese. They first studied their eating habits using the "Yale food addiction scale," which rated each of the women by their eating habits. Symptoms of food addiction, which are part of the scale, include: eating much more than planned, eating to the point of feeling physically ill and using food to mitigate feelings of anxiety or depression.
They were separated into the "high food addiction" group — those who showed three or more symptoms — and the "low food addiction" group — who showed one or fewer symptoms. The two groups were approximately the same in age and body mass index, or BMI, a measure of fatness based on a ratio of height and weight.
Each group was given a brain scan while being shown an image of either a Häagen-Dazs chocolate shake or a tasteless, saliva-like solution. In 60 percent of the trials, the image was followed with actual tasting of the beverage, while the rest of the time no food was delivered.
It seems that for some, their drug of choice is food, in this case the chocolate milkshake. These people showed high scores on the "food addiction" test and showed high activation of this brain pathway when they were offered the milkshake.
Anticipation and reward
Researchers saw that participants with high food-addiction ratings showed signs of reduced inhibition control when given the food. "Consumption of palatable food may override desires to limit caloric food consumption in participants with high FA [food addiction], resulting in disinhibited food consumption," the authors write, which might lead those with high food addiction tendencies to eat more.
Interestingly, the levels of food addiction and brain activation weren't correlated to the test subject's body mass index. Subjects with high food addiction scores were no more likely to be obese or overweight than those with low food addiction scores. Those with high food addiction scores may be more at risk for future weight gain, the researchers note, especially since the study participants are fairly young.
In fact, they did find those who scored high on the food addiction scale also showed signs of binge eating, emotional eating and other kinds of problematic eating.
"It is possible that some individuals experience compulsive eating behavior but engage in compensatory behaviors to maintain a lower weight," they write.
The study will be in the August print issue of the journal.
You can follow LiveScience staff writer Jennifer Welsh on Twitter @microbelover.
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