Newswise — People who have a pattern of heavy drinking showed less impairment than light drinkers after drinking similar amounts of alcohol — yet this difference depends largely on how much time has elapsed after drinking and may only be evident at moderate intoxication. A study published in Alcohol: Clinical and Experimental Research found that people who exceed drinking an amount of alcohol that is typical for them showed substantial impairment. And, when heavy drinkers and lighter drinkers were similarly impaired, the heavy drinkers perceived themselves to be less impaired, which may lead to risky decisions.
The study tested the commonly held assumption that people who regularly drink in excess are better able to ‘hold their liquor’ than people who don’t regularly drink as much. Researchers examined data from the Chicago Social Drinking Project (CSDP), a placebo-controlled laboratory study of acute responses to alcohol.
Four hundred young adults were categorized based on their drinking patterns as light drinkers, heavy social drinkers, or as having alcohol use disorder. On average, the light drinkers drank three drinks per week and drank about a quarter of days in the month. Heavy social drinkers drank almost twenty drinks per week and tended to drink about half the days in the month. People with alcohol use disorder averaged nearly forty drinks per week and drank three out of four days a month.
Participants were given specific doses of alcohol and then tested for breath alcohol content and performance on fine motor skills and short-term memory tests half an hour, two hours, and three hours after drinking.
When they drank alcohol in amounts equivalent to a binge drinking episode--four or more drinks for women or five or more for men—the heavier drinkers showed greater tolerance than the lighter drinkers, performing better on the tests of fine motor skills and working memory with quicker recoveries as well as reporting feeling less impaired than the light drinker group. However, when participants with alcohol use disorder drank a very high dose of alcohol that more closely aligned with their usual drinking pattern, they showed substantial impairments in working memory and fine motor skills, which were greater than those in light drinkers at the binge dose. Additionally, in the first thirty minutes after alcohol consumption, the light and heavier drinking groups all showed impairment, but the heavy drinker and alcohol use disorder groups perceived themselves to be less impaired. This misperception of impairment can lead to increased drinking and risky decision-making.
Other studies have suggested that people who regularly drink to excess learn how to manage impairing effects of alcohol. However, this study suggests that tolerance might dissipate with high quantities of alcohol that are common for drinkers with alcohol use disorder. The authors note that it cannot be construed from the study that habitual drinking causes the development of tolerance.
Holding your liquor: Comparison of alcohol-induced psychomotor impairment in drinkers with and without alcohol use disorder. N. Didier, A. Vena, A. Feather, J. Grant, A. King (p. xx – xxx)
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