Obesity and drug addiction share commonality

  Dopamine plays a key role in drug addiction and obesity

A recent study by researchers at The Scripps Research Institute published March 28, 2010, show that the molecular mechanisms that push persons into chemical dependency underlie compulsions to overeat, and thus become obese.

This "Study shows compulsive eating shares addictive biochemical mechanism with cocaine, and heroin abuse," according to the study.

For too many people then, bacon, candy, french fries, and many other fattening foods are like abusing cocaine, or heroin.

Research Associate Professor Paul J. Kenny and graduate student Paul M. Johnson devised a study involving feeding rats a modified diet resembling the type contributing to human obesity. The rats were served foods easy to obtain, high in calories, and fatty like sausage, bacon, and cheesecake. Shortly after the study started, the rats gained blew up in weight.

"They always went for the worst types of food," Kenny said, "and as a result, they took in twice the calories as the control rats. When we removed the junk food and tried to put them on a nutritious diet – what we called the 'salad bar option' – they simply refused to eat. The change in their diet preference was so great that they basically starved themselves for two weeks after they were cut off from junk food. It was the animals that showed the "crash" in brain reward circuitries that had the most profound shift in food preference to the palatable, unhealthy diet. These same rats were also those that kept on eating even when they anticipated being shocked," the report stated.

"In rat models the development of obesity coincides with a progressively deteriorating chemical balance in reward brain circuitries. As these pleasure centers in the brain become less and less responsive, rats quickly develop compulsive overeating habits, consuming larger quantities of high-calorie, high-fat foods until they become obese. The very same changes occur in the brains of rats that overconsume cocaine or heroin, and are thought to play an important role in the development of compulsive drug use," noted the report.

At the heart of  the study are brain chemistry shenanigans occurring from the ingestion of fattening foods, just as there are changes in substance abuser brain chemistry from drugs.

Researchers Kenny and Johnson also investigated the underlying molecular mechanisms to explain the changes in brain chemistry. The pair zeroed in on the dopamine D2 receptor identified as playing a key role in vulnerability to chemical dependency, and obesity. This is the same receptor that responds to the neurotransmitter dopamine that is released in the brain by pleasurable experiences such as sex, eating food, and drugs such as cocaine and heroin.

Dopamine is known as the "feel good" neurotranmitter because it signals to us that eveything is just peachy even if your house is burning, you owe $100,000 to Visa, your wife just left you, and she took the only car.

"In cocaine abuse, for example, the drug alters the flow of dopamine by blocking its retrieval, flooding the brain and overstimulating the receptors, something that eventually leads to physical changes in the way the brain responds to the drug. The new study shows that the same thing happens in junk food addiction ," according to the report.

According to Professor Kenny, "These findings confirm what we and many others have suspected, that overconsumption of highly pleasurable food triggers addiction-like neuroadaptive responses in brain reward circuitries, driving the development of compulsive eating. Common mechanisms may therefore underlie obesity and drug addiction." 

If you or a loved one needs help with any type of drug abuse/addiction problem, contact these sites depending on where you live. SEMCA (Wayne County residents), CARE (Macomb County residents), PACE (Oakland County residents), Drug Free Detroit (City of Detroit residents). For those residing outside the State of Michigan, contact SAMHSA for assistance. For assistance with medical marijuana contact The Michigan Medical Marijuana Association, or Michigan Medical Marijuana Certification Center.

In the flow...

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 (Photo National Institute of Health - Wikimedia Creative Commons)