Overeating a Form of Addiction

Study tracks stomach-to-brain nerve signals in obese people

MONDAY, Oct. 2, 2006 (HealthDay News) -- Eating can be a form of addiction for obese people, suggests a new study that used a device to monitor stomach-to-brain signals.

"We found that areas of the brain that received signals were the hippocampus, which is involved in memory and emotion, and also the frontal cortex," said Dr. Gene-Jack Wang, head of the medical department at Brookhaven National Laboratory in Upton, N.Y. He's also lead author of a report on the findings, published in this week's issue of the Proceedings of the National Academy of Sciences.

The hippocampus is known to be involved in drug addiction, Wang noted.

"An obese person, even if he becomes lean, still has the signals in the area of the hippocampus, so there is a high likelihood that he will relapse," Wang said.

That's the pessimistic view. A more hopeful evaluation comes from Dr. Mark Gold, a professor of psychiatry and neuroscience at the University of Florida's McKnight Brain Institute, who has long proposed that eating can be an addiction.

"The advantage of having a novel hypothesis means that we might be able to develop new treatments for obesity similar to those for drugs of abuse," Gold said. "This opens a whole range of treatment possibilities."

Wang's team used a device called an Implantable Gastric Stimulator, originally designed to help people stop eating by sending a signal to the brain that the stomach was enlarged, therefore full. The device, made by a company that no longer exists, never won approval.

The Brookhaven researchers used the stimulator on seven obese human volunteers to track signals sent from the stomach to the brain via the vagus nerve. The vagus nerve was monitored because "it sends the signal to the brain about how much we ate, and if we need to eat or not," Wang said.

The pattern of activity the researchers saw "suggests that similar brain circuits underlie the enhanced motivational drive for food and drugs seen in obese and drug-addicted subjects, respectively," the report said.

How can the information be used to help people avoid excess weight? "That is the million-dollar question," Wang said. "We must study to learn more about how the signal is transmitted and how to treat obesity. As with drug addiction, we might also have to treat the emotions."

Gold's take on the study is that "the biggest reason this is interesting is that bariatric [stomach-reduction] surgery for obesity is the fastest-growing procedure in the United States, and this paper suggests that alternative and reversible procedures can be done once the stomach-brain connections are matched. We should be able to identify sites within the stomach that are most likely to reduce hunger and appetite or induce a sense of fullness, either of which would be a novel alternative."

But "eating behavior is so complicated," Wang added. "Even if you are under stringent circumstances, you must eat."

More information

For more on treating obesity, visit the American Obesity Association.

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