| New Food-Addiction Link Found | |
A recent study by the U.S. Department of Energy’s Brookhaven National Laboratory found that the mere sight or smell of food spikes levels of the brain "pleasure" chemical, dopamine. The study's findings were published in the June 1, 2002, issue of Synapse. The research showed that the mere display of food causes a significant elevation in brain dopamine, a neurotransmitter associated with feelings of pleasure and reward.
In the study, food-deprived subjects were allowed to smell and taste their favorite foods without actually eating them. The display of these foods caused a significant elevation in brain dopamine. This activation of the brain’s dopamine motivation circuits is distinct from the role the brain chemical plays when people actually eat, and may be similar to what addicts experience when craving drugs. Psychiatrist Nora Volkow, the study’s lead investigator, stated:
Scientists investigated the role of dopamine in food intake in healthy, non-obese individuals. The researchers used PET (Positron Emission Tomography) scans -- a brain-scanning technique -- to measure dopamine levels in 10 food-deprived volunteers. Each volunteer was given an injection containing a radiotracer, a radioactive chemical "tag" designed to bind to dopamine receptors in the brain.
The subjects’ brains were scanned four times over a two-day period, with and without food stimulation, paired with and without an oral dose of methylphenidate. Methylphenidate (Ritalin) is known to block the reabsorption of dopamine into nerve cells. The researchers wanted to see if it would amplify any subtle changes in dopamine levels.
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"Eating is a highly reinforcing behavior, just like taking illicit drugs. But this is the first time anyone has shown that the dopamine system can be triggered by food when there is no pleasure associated with it since the subjects don’t eat the food. This provides us with new clues about the mechanisms that lead people to eat other than just for the pleasure of eating, and in this respect may help us understand why some people overeat."
A significant number of studies have been conducted at Brookhaven focusing on the relationship between addictive drugs and dopamine levels in the brain. These studies have shown that addicts have fewer dopamine receptors than non-addicts. In an effort to understand how dopamine relates to obesity, the researchers found that obese individuals also had fewer dopamine receptors than normal control subjects.
