The research, published in Archives of General Psychiatry, found that people with addictive-like eating behaviours appear to have greater neural activity in regions of the brain that are associated with substance dependence, including elevated activation of reward circuitry in response to food cues, and reduced activation of inhibitory regions in response to food intake.
The study, which the authors claim is the first to assess the neural activation of addictive-like eating behaviours in humans, may help to explain why it is difficult for certain people to maintain a healthy weight.
“Food and drug use both result in dopamine release in mesolimbic regions [of the brain] and the degree of release correlates with subjective reward from both food and drug use” said the researchers, led by Ashley Gearhardt of Yale University in Connecticut
“If food cues take on enhanced motivational properties in a manner analogous to drug cues, efforts to change the current food environment may be critical to successful weight loss and prevention effort,” they added.
Ubiquitous food advertising and the availability of inexpensive palatable foods may be making it “extremely difficult” to stick with healthy food choices – “because the omnipresent food cues trigger the reward system,” explained the researchers.
According to the authors, one-third of American adults are now obese, and obesity-related disease is the second leading cause of preventable death in the US.
“Unfortunately, most obesity treatments do not result in lasting weight loss because most patients regain their lost weight within 5 years,” said the researchers.
They explained that theorists have proposed that addictive processes may be involved in the etiology of obesity.
“Although parallels in neural functioning between obesity and substance dependence have been found, to our knowledge, no studies have examined the neural correlates of addictive-like eating behaviour,” said Gearhardt and co-workers.
The researchers used functional magnetic resonance imaging (fMRI) to study the brain activity of 48 young women (ranging from lean to obese) who were offered a chocolate milkshake or a tasteless solution. The authors also measured food addiction symptoms, as assessed by the Yale Food Addiction Scale (YFAS).
Gearhardt and her co-workers found food addiction scores correlated with greater activation in areas of the brain including the anterior cingulate cortex (ACC), medial orbitofrontal cortex (OFC), and amygdala in response to anticipated receipt of food.
“Elevated food addiction scores were associated with greater activation of regions that play a role in encoding the motivational value of stimuli in response to food cues. The ACC and medial OFC have both been implicated in motivation to feed and to consume drugs among individuals with substance dependence,” said the researchers.
They said that their findings support the theory that compulsive food consumption may be driven in part by an enhanced anticipation of the rewarding properties of food, in a similar way to individuals with drug addictions are likely to be physiologically, psychologically, and behaviourally reactive to substance-related cues.
“If certain foods are addictive, this may partially explain the difficulty people experience in achieving sustainable weight loss,” said Gearhardt and colleagues.
Source: Archives of General Psychiatry
Published online ahead of print, doi: 10.1001/archgenpsychiatry.2011.32
“Neural Correlates of Food Addiction”
Authors: A.N. Gearhardt, S. Yokum, P.T. Orr, E. Stice, W.R. Corbin, K.D. Brownell