Shifts in brain chemicals explain causes of alcoholism, relapses
New studies of the effects of alcohol on brain chemistry help to explain why alcoholics experience long-lasting feelings of tension and distress. They also provide a key to why some drinkers develop alcoholism in the first place, and why they tend to relapse, even after protracted abstinence. The studies were described here today at the national meeting of the American Chemical Society, the world's largest scientific society.
George F. Koob, Ph.D., a scientist at The Scripps Research Institute, La Jolla, said animal studies indicate that heavy drinking depletes the brain's supplies of dopamine, gamma aminobutyric acid, opioid peptides and serotonin systems--chemicals that are responsible for our feelings of pleasure and well-being. At the same time, it promotes the release of stress chemicals, such as corticotropin releasing factor (CRF), that create tension and depression. In combination, the depletion of pleasure chemicals and the stimulation of stress chemicals creates a persisting chemical imbalance that leaves the alcoholic vulnerable to relapse, he said.
Hoping to suppress the dark feelings aroused by CRF, alcoholics drink more-but the more they drink, the more CRF is produced. This cycle ultimately raises the "set point" for alcohol intake, or the amount it takes to make an alcoholic feel "normal," according to Koob. He says some data from animal studies suggest that CRF remains active as long as four weeks after someone stops drinking.
At present, family history is the only indicator of vulnerability to alcoholism. Among individuals who have an alcoholic parent, men have a five-to-one chance, and women a two- or three-to-one chance of developing the disease, said Koob. His study could point the way toward the identification of specific chemical markers-as an example, perhaps low levels of dopamine and high levels of CRF that could better warn of danger ahead.
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