The compulsion for either food or drugs emerges from the same neural pathways and chemicals in the brain, suggesting that overeating and substance abuse are "two sides of the same coin," according to a report published today in Psychiatric News.
The report is a summary of evidence presented last month at a conference sponsored by the National Hispanic Science Network on Drug Abuse. Several scientific presentations promoted the idea that addictive drugs hijack the normal food reward system that humans need to survive. For example, the dopamine signaling system in the brain is activated by food cues, such as the smell of turkey roasting in the oven. This system drives us to eat and feel satisfied after eating. But brain-imaging studies show this same system is at the core of drug addiction.
"Drugs activate [dopamine release] in a much more efficient and potent way than food," said Dr. Nora Volkow, director of the National Institute on Drug Abuse. "The motivational drive produced by drugs is much more intense than food."
Brain studies show compulsive overeating shares many "characteristics with drug addition," Volkow said. The amount of dopamine receptors in the brain is reduced in obese people, as it is people with long-term addiction to drugs. Another study presented at the meeting, by Dr. Roger McIntyre of the University of Toronto, showed an inverse relationship between obesity and substance abuse among people with bipolar disorder. People with bipolar disorder have higher-than-average rates of obesity and substance abuse. But McIntyre found that the obesity rate in bipolar patients was much lower among those with substance abuse disorder.
Scientists say they hope that more research on this neurocircuitry could yield new treatments for both overeating and addiction.
-- Shari Roan
Photo credit: Andy Rain / European Pressphoto Agency