Ability to ‘Handle Your Alcohol’ More Complex Than Thought

New research from the University of Chicago suggests that the ability to “handle your alcohol” isn’t as straightforward as it might seem. This study involved three groups of young adults in their 20s, each with different drinking habits. The researchers found that individuals with alcohol use disorder (AUD), previously known as alcoholism, performed better on fine motor and thinking tasks than light or heavy social drinkers after having an amount of alcohol that would legally make someone drunk, which is about four to five drinks.

However, when those same individuals with AUD had more alcohol, similar to what they usually drink (around seven to eight drinks), they performed significantly worse on the same tasks. This was more than double the decrease in performance they experienced after the initial amount of alcohol, and they didn’t return to normal even three hours later.

Andrea King, a professor from UChicago and the lead author of the study, said, “There’s a lot of thinking that when experienced drinkers (those with AUD) consume alcohol, they are tolerant to its impairing effects. We supported that a bit, but with a lot of nuances. When they drank alcohol in our study at a dose similar to their usual drinking pattern, we saw significant impairments on both the fine motor and cognitive tests that was even more impairment than a light drinker gets at the intoxicating dose.”

This study, part of the Chicago Social Drinking Project, started by King in 2004, examines how substances like alcohol, caffeine, and antihistamines affect mood, performance, and behavior in people with different drinking habits. The research worked with three groups: light drinkers who don’t often drink a lot at once, heavy social drinkers who often drink a lot at once, and drinkers who meet the criteria for AUD and often drink a lot more than once a month.

In the experiment, participants were given a drink containing either alcohol, a stimulant, a sedative, or a placebo. The alcoholic beverage was a flavored drink mix in water with very strong alcohol at 16% volume based on body weight, which is similar to four to five drinks. This amount of alcohol is enough to get a typical drinker drunk. The participants finished the drink within 15 minutes.

They took a breathalyzer test and completed two performance tasks half an hour, one hour, two hours, and three hours after having the drink. The first task tested their fine motor skills, where they had to pick up, turn, and place a grooved metal peg into 25 randomly placed holes on a metal board as quickly as possible. The second task was a paper and pencil task to test thinking skills, in which the participants had to match symbols from a key pair onto a numbered grid as quickly and correctly as possible.

Half an hour and three hours after drinking the beverage, participants were also asked to rate how drunk they felt. The AUD and heavy social drinkers reported feeling less drunk than the light drinkers. Although they did show less overall effects from the alcohol on the motor and thinking tests, half an hour after drinking, they were just as slow on the fine motor test as the light drinkers. They also returned to their normal levels faster, suggesting they had more tolerance and could “handle their alcohol” better than people who don’t drink as much.

However, those with AUD often don’t stop after four or five drinks. Therefore, some of the AUD drinkers in the study took part in a separate session where they drank an amount more in line with their regular habits, equivalent to about seven or eight drinks. With this larger amount of alcohol, they showed more than double the amount of mental and motor skill decline than after they had the legal limit of alcohol. Even after three hours, they never returned to their normal performance levels. Their level of decline even exceeded that of the light drinkers who

had the legal limit of alcohol, suggesting that the more someone drinks, the worse the physical effects, regardless of how experienced they are.

“I was surprised at how much impairment that group had to that larger dose, because while it’s 50% more than the first dose, we’re seeing more than double the impairment,” King said.

She has also conducted research showing that heavy social drinkers and those with AUD enjoy alcohol more and want to drink more than their lighter-drinking counterparts. “They’re having the desire or craving to drink more and more, even though it’s impairing them. It’s really a double-edged sword,” she said.

Deaths from drunk driving have significantly dropped since the minimum drinking age was set at 21 in 1984 and after public awareness campaigns. However, the Centers for Disease Control and Prevention reports that over 140,000 people still die from too much alcohol use in the U.S. each year, and alcohol intoxication is still involved in 30% of traffic deaths. King believes that understanding the effects of intoxication more fully could help prevent more harm.

“It’s costly to our society for so many reasons, that’s why this study is just so important to understand more,” she said. “I’m hoping we can educate people who are experienced high-intensity drinkers who think that they’re holding their liquor or that they’re tolerant and won’t experience accidents or injury from drinking. Their experience with alcohol only goes so far, and excessive drinkers account for most of the burden of alcohol-related accidents and injury in society. This is preventable with education and treatment.”

The study, “Holding your liquor: Comparison of alcohol-induced psychomotor impairment in drinkers with and without alcohol use disorder,” was supported by the National Institute on Alcohol Abuse and Alcoholism and the National Institute on Drug Abuse. Other contributors to the research include Nathan Didier, Ashley Vena, Abigayle Feather, and Jon Grant from the University of Chicago.