Turning Off Alcohol Abuse
Studies of brain circuits and neurotransmitters in
“alcoholic” animals suggest new ways to modulate drinking, offering hope
that such treatments may one day help human alcoholics overcome their
-- Karen McNulty Walsh
Stopping alcohol abuse will never be as easy as turning on or off a ‘switch,’” says Panayotis (Peter) Thanos, a neuroscientist at the U.S. Department of Energy’s (DOE’s) Brookhaven National Laboratory. “But understanding the brain’s reward circuits and finding ways to modulate them could play a role in developing successful treatments.”
His research — funded by the Office of Biological and Environmental Research within DOE’s Office of Science, the National Institute on Drug Abuse, the National Institute on Alcohol Abuse and Alcoholism (NIAAA), and others — shows that he’s on to something. Through brain-imaging and behavioral studies in animals, Thanos and his colleagues have demonstrated that a variety of brain receptors play a role in excessive drinking — and that changing the levels of these receptors or their ability to send pleasure/reward signals can drastically affect drinking behavior.
“These studies improve our understanding of the mechanism or mechanisms of alcohol addiction and strengthen our hope that these methods might one day be developed into treatments to help people addicted to alcohol,” Thanos said.
The pleasure of dopamine
One of the first brain chemicals Thanos’ group investigated was the neurotransmitter dopamine. Many studies have shown that alcohol, like all addictive drugs, increases the brain’s production of dopamine, which sends a strong reinforcing signal of pleasure and reward.
Over time, however, the brain responds to this constant dopamine stimulation by “down-regulating,” or decreasing, the number of a particular type of dopamine receptors — nerve cell proteins to which the neurotransmitter must bind to send the pleasure signal. Alcoholics then may drink more and more to try to override this blunted pleasure response. And people with initially low levels of these dopamine receptors (known as D2 receptors) might be particularly prone to abuse alcohol or other drugs.
If this is true, Thanos hypothesized, then perhaps increasing the level of D2 receptors would decrease drinking.