Two of the most challenging health problems in America today are drug abuse and obesity. The search for ways to unlock the secrets of both types of addiction may have just gotten a boost. Results of new research, funded by the National Institute on Drug Abuse (NIDA), a component of the National Institutes of Health (NIH), show that some of the same brain mechanisms that fuel drug addiction in humans also accompany the emergence of compulsive eating behaviors and development of obesity in animals.
About the Study
The study, “Dopamine D2 receptors in addiction-like reward dysfunction and compulsive eating in obese rats,” conducted by researchers at the Scripps Research Institute, Jupiter, Florida, was released in the online version of Nature Neuroscience (http://www.nature.com/neuro/journal/vaop/ncurrent/full/nn.2519.html) March 28, 2010, and will appear in the May 2010 print issue. When researchers gave rats unlimited access to high-fat food in varying levels, they found that unrestricted availability alone can trigger addiction-like responses in the brain, leading to compulsive eating behaviors and the onset of obesity.
Both obesity and drug addiction, say researchers, have been linked to a dysfunction in the brain’s reward system.
Overconsumption in both cases can trigger a gradual increase in the reward threshold. This results in the requirement of more and more palatable high-fat food or reinforcing drug to satisfy the cravings over time.
Dr. Nora D. Volkow, director of NIDA, commenting in a press release on the study (http://www.eurekalert.org/pub_releases/2010-03/niod-cmo032610.php) said, “This research opens the door for us to apply some of the knowledge we have gathered about drug addiction to the study of overeating and obesity.”
The study results appear to support the idea that type 2 dopamine receptors (D2DR) – brain receptors that have been shown to play a key role in addiction – also play a key role in the rats’ heightened response to food. As the rats became obese, levels of D2DR in the brain’s reward circuit decreased. This drop in D2DR, say researchers, is similar to what happens in humans addicted to drugs like heroin or cocaine.
Paul J. Kenny, one of the study’s co-authors and an associate professor at Scripps Jupiter, Florida research facility, points out the potential implications. “It is possible that drugs developed to treat addiction may also benefit people who are habitual overeaters.”
Paul Johnson, co-author and graduate student in the department of molecular therapeutics, has this to say: “Hopefully, this will change the way people think about eating. It demonstrates how just the availability of food can trigger overconsumption and obesity.”
Read more about Drug Abuse and Obesity: What Do They Have in Common?