by Rachel Harris
Many addictive drugs, such as nicotine, alcohol, and amphetamines, change the levels of dopamine in an area of the midbrain called the substantia nigra. In disrupting the dopamine systems in the brains, these drugs interrupt the brain’s quest for rewards and control of decisions. Recently, the obesity epidemic has catalyzed many psychologists to examine how food consumption acts on the brain in ways similar to substances more typically associated with addiction. Researchers at the National Institute on Drug Abuse have compared brain images of obese people and methamphetamine users. They have found that fewer dopamine receptors in both groups, when compared to a normal control group. Moreover, the signs of drug addiction: developing tolerance, withdrawal symptoms, and overwhelming involvement are also seen with food. [Editor's note: More on food "addiction" in this post on the hazards of delicious food. ] In addition, the absence of food is seen to cause withdrawal symptoms in rats. Although these results cannot be directly applied to humans, this study suggests that food might create powerful motivations to eat not only because the taste is rewarding, but also because eating reduces anxiety or stress.