A young adult’s acute response to alcohol predicts whether he or she will escalate to problem drinking within 2 years, but not in the way in which most experts would expect, according to a report in the April issue of the Archives of General Psychiatry.
Young adults who experience greater positive effects from drinking – for example, reporting that they like and want more of alcohol’s stimulant effects – and lesser negative effects such as sedation are more likely to drink heavily and to progress to problem drinking. In contrast, those who do not experience high levels of positive effects but have greater negative effects – for example, attaining only a mild "buzz" and then rapidly feeling sluggish – are less likely to drink heavily and progress to problem drinking.
"Although the finding that heavier drinkers enjoy the effects of alcohol more than lighter drinkers seems intuitive, there has been limited evidence thus far to support this notion. Indeed, the prevailing model, the low-level response theory, posits that persons who experience a lower level of response to alcohol will engage in heavier drinking over time because they do not feel the internal cues of intoxication" or the warning signs to stop drinking, said Andrea C. King, Ph.D., of the department of psychiatry and behavioral neuroscience at the University of Chicago and her associates.
The investigators studied drinking in 190 healthy volunteers aged 21-35 years, including 85 women and 105 men. In all, 104 of these subjects were classified as heavy drinkers, consuming 10-40 standard alcoholic drinks per week and engaging in regular binge drinking (consuming five or more drinks at one time, and doing so between one and five times per week). The remaining 86 subjects were classified as light drinkers, consuming one to five standard alcoholic drinks per week and engaging in binge drinking five or fewer times per year.
In the first phase of the study, the subjects were assigned in random order to three individual, 5-hour laboratory sessions in which they drank a placebo beverage, a low-alcohol beverage, or a high-alcohol beverage; they were then assessed at 30, 60, 120, and 180 minutes. In the second phase of the study, the subjects were followed every 3 months for 2 years to assess changes in their everyday patterns of alcohol use.
The heavy drinkers showed a markedly different acute response to alcohol than did the light drinkers.
Heavy drinkers reported feeling greater positive and rewarding effects, particularly at the high dose of alcohol. They enjoyed the stimulant effects of drinking to a greater degree, and said that they "wanted more." They did not experience much sedation. In contrast, light drinkers did not experience the positive or rewarding effects of alcohol as much, did not enjoy the stimulant effects as much, and did not "want more." They reported higher sedation and feeling tired and sluggish after drinking, particularly after drinking the high-dose beverage. Light drinkers also showed increases in salivary cortisol levels (a marker of stress) when "coming down" from the high-dose beverage, whereas heavy drinkers did not.
"Collectively, these responses may serve as a protective factor underlying [light] drinkers’ ability to ‘put the brakes on’ and limit their drinking," Dr. King and her colleagues said (Arch. Gen. Psych. 2011;68:389-99).
During the 2-year follow-up, few light drinkers increased their alcohol consumption. In contrast, heavy drinkers were likely to maintain or increase their alcohol intake, particularly to raise their frequency of binge drinking. These subjects increased their likelihood of meeting DSM-IV criteria for alcohol abuse and dependence, the researchers said.
"Taken together, [our] results indicate that the low-level response theory should be revised to include heightened sensitivity to rewarding and stimulating alcohol effects as equally important predictors as lack of sedative responses in the development and maintenance of problematic drinking among at-risk persons," they added.
"We plan to continue to follow up these participants to examine their drinking patterns over a longer time."
One important limitation of the study is the legal requirement that participants be at least aged 21 years to be given alcohol. Therefore, "it is unclear whether the findings can be generalized to younger drinkers," Dr. King and her colleagues wrote.
This study was supported by the National Institute on Alcohol Abuse and Alcoholism, the comprehensive cancer center at the University of Chicago, and the National Center for Research Resources. No conflicts of interest were reported.