Different Effects of Alcohol May Explain Binge Drinking in Young Adults

Differences in short-term reaction to alcoholic beverages may help explain why some young adults are heavy drinkers while others are light drinkers, according to new research appearing in the June issue of Alcoholism: Clinical and Experimental Research.

"Young adult binge drinkers show -- heightened sensitivity to stimulant-like alcohol effects and greater tolerance to sedative alcohol effects, compared to their light-drinking counterparts," reports lead author Andrea C. King, Ph.D., of the University of Chicago's Department of Psychiatry. Binge drinkers, in other words, are more likely to experience one of alcohol's more desirable effects, while light drinkers tend to experience one of its less desirable effects more profoundly.

"Heavy [alcohol] drinking among young adults is a serious problem in this country -- and the consequences of this excessive use, both financial and personal, are widespread," King explains.

The cost of health care, lost productivity, crime and accidents due to alcohol consumption has been estimated to exceed $148 million a year in the United States alone. Those who start drinking at a younger age are more likely to suffer alcohol's many ill effects and have lifetime problems with alcohol. Therefore, King observes, "understanding the factors that contribute to escalation and maintenance of excessive [alcohol consumption] is crucial to improve prevention, public education and early intervention strategies."

King and her colleagues recruited 34 young men and women between the ages of 24 and 38 who could be described as "heavy drinkers" or "light drinkers." The 14 light drinkers consumed no more than five drinks a week and never engaged in binge drinking (defined as five or more drinks on one occasion for a man, or four for a woman). The 20 heavy drinkers regularly consumed at least 10 drinks a week and binged one to four times each week.

Members of both groups came to a comfortable laboratory environment, resembling a living room, on three separate occasions. Each participant was given a beverage containing an undisclosed amount of alcohol: either a high dose based on his or her weight, a moderate dose, or just enough alcohol to impart an alcoholic taste. Over the following three hours, while blood alcohol levels rose and then fell, each subject repeatedly answered questions that measured levels of stimulation and sedation. At the same time, the researchers monitored the participants' activities, taking saliva samples and other recordings at regular intervals.

The research team's findings reveal that heavy drinkers generally experience sharp and short-lived stimulation approximately 15 minutes after finishing a high dose of alcohol, while blood alcohol levels are still rising. Their enjoyment of this effect is evident from their frequent reports of liking how they feel and wanting to drink more while stimulated. Light drinkers tend not to experience this pleasant, stimulating sensation at any time after consuming a high dose of alcohol; instead, they are likely to report feeling sluggish and drowsy while their blood alcohol levels are increasing.

Other findings indicate that heavy drinkers are not only more likely to enjoy one of the "up" sides of drinking, but are also less affected by two of its "down" sides: sedation and stress. Those who regularly consume larger amounts of alcohol usually don't feel sedated until after their blood alcohol levels have peaked and are on the decline; light drinkers begin to feel sedated before the peak. Moreover, the heavy drinkers report feeling far less sedated overall than the light drinkers do.

The stress experienced when light drinkers consume a high dose of alcohol, King explains, is revealed by increased blood levels of a stress hormone. Heavy drinkers tend to have relatively constant levels of this hormone after consuming a similar amount of alcohol.

"The light drinkers' absence of alcohol stimulation, in combination with increased sedation and stress hormone levels after alcohol consumption, may be important factors in rendering them at very low risk for the development of future alcohol disorders," King notes.

Funding for the study came from the Alcoholic Beverage Medical Research Foundation and the National Institute on Alcohol Abuse and Alcoholism.