Upton, NY — Many studies have suggested that genetic differences make some individuals more susceptible to the addictive effects of alcohol and other drugs. Now scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory provide the first experimental evidence to directly support this idea in a study in mice reported in the October 19, 2010, issue of Alcoholism Clinical Experimental Research.
The study compared the brain’s response to long-term alcohol drinking in two genetic variants of mice. One strain lacked the gene for a specific brain receptor known as dopamine D2, which responds to dopamine, the brain’s “feel good” chemical, to produce feelings of pleasure and reward. The other strain was genetically normal. In the dopamine-receptor-deficient mice (but not the genetically normal strain), long-term alcohol drinking resulted in significant biochemical changes in areas of the brain well know to be involved in alcoholism and addiction.
“This study shows that the effects of chronic alcohol consumption on brain chemistry are critically influenced by an individual’s pre-existing genetic makeup,” said lead author Panayotis (Peter) Thanos, a neuroscientist with Brookhaven Lab and the National Institute on Alcohol Abuse and Alcoholism (NIAAA) Laboratory of Neuroimaging. “Our findings may help explain how someone’s genetic profile can interact with the environment—in this case, chronic alcohol drinking—to produce these changes only in some individuals, but not in others with a less vulnerable genetic profile. The work supports the idea that genetic screening could provide individuals with valuable information relevant to understanding risks when deciding whether or not to consume alcohol.”
The scientists were particularly interested in the dopamine system because a wide range of studies at Brookhaven and elsewhere suggest that deficiency in dopamine D2 receptors may make people (and animals) less able to experience ordinary pleasures and more vulnerable to alcoholism, drug abuse, and even obesity. The ability to breed mice completely lacking the D2 gene—and carefully control and monitor their alcohol intake—made it possible to test the effect of this genetic influence on the brain’s response to chronic alcohol drinking for the first time in this study.