Chemical Roots of Alcoholism Traced by Scientists

Scientists have identified a chemical that, when lacking in mice, causes them to overindulge in alcohol. The substance, neuropeptide Y, has already been implicated in a wide range of emotional states and behaviors, including overeating, anxiety and depression. It is actively being pursued by pharmaceutical companies as the basis for behavior-modifying drugs. Similarly, the recent findings may one day be applied to a drug that treats alcoholism.

Scientists first suspected that neuropeptide Y played a role in alcoholism while studying rats, who along with humans depend on the brain chemical for a wide range of mental and physical functions. Rats that have been selectively bred to be heavy drinkers have low concentrations of the chemical in their brains.

To pursue the alcoholism-neuropeptide Y link further, Todd Tiele of the University of Washington and colleagues genetically engineered mice to produce lower-than-normal quantities of the chemical. They provided these mice and normal ones with unlimited access to alcohol via the water spigots in their cages. The neuropeptide Y-deficient mice drank twice as much as the others. They were also less sensitive to alcohol's sedative effects, recovering faster after drinking-induced stupors. The results were reported in the November 26, 1998 issue of Nature.

These findings mesh with studies in humans. Heavy drinkers seem to be less physically affected by alcohol than others. College age drinkers with a greater tolerance for alcohol are more prone to become alcoholics later in life than their more "light-weight" counterparts.

The findings also agree with previous studies linking neuropeptide Y and anxiety. Neuropeptide Y-deficient mice are more prone not only to heavy drinking but also to anxiety. The connection suggests that mice-and humans-lacking in the chemical might turn to drinking as a way to soothe their nerves.

This tendency may be similar to one seen in smokers. Research suggests that smokers "self-medicate" with nicotine as a way of correcting chemical imbalances in their brains associated with depression.

The Washington team's findings offer hope that a drug designed to raise neuropeptide Y levels may reduce cravings for alcohol. While the findings bode well for alcoholism treatment, they do not look good for the diet pill business. Previous research has shown that high levels of neuropeptide Y stimulate appetite. Based on this finding, some have speculated that drugs designed to lower concentrations of the chemical may help reduce the appetites of overeaters. But given the new findings, these drugs may have the unintended consequence of promoting drinking.

Sources

"Smoking May Protect Some High-Risk Women From Breast Cancer." David Brown. Washington Post, May 20, 1998, page A16.

"Study Links Gene Pattern to Strong Alcohol Addiction." Thomas H. Maugh. Los Angeles Times, March 4, 1998, page 1A.