People with alcohol use disorder (AUD) show the same or even more levels of fine motor and cognitive impairment as light/moderate drinkers when consuming their usual excessive amount, new research has shown.

While heavy drinkers can tolerate a certain amount of alcohol better than light or moderate drinkers, the concept of "holding your liquor" is more nuanced than commonly believed, according to new research from the University of Chicago.

"There's a lot of thinking that when experienced drinkers (those with AUD) consume alcohol, they are tolerant to its impairing effects," said Andrea King, a professor of psychiatry and behavioural neuroscience and senior study author.

However, when they drank alcohol at a dose similar to their usual drinking pattern, "we saw significant impairments on both the fine motor and cognitive tests that were even more impairment than a light drinker gets at the intoxicating dose."

The researchers conducted the study, published in the journal Alcohol: Clinical and Experimental Research, with three groups of young adults in their 20s with different drinking patterns.

The groups were light drinkers who do not binge drink, heavy social drinkers who binge drink several times a month, and drinkers who meet the criteria for AUD and binge drink frequently, at least one-third or more days in a typical month.

The AUD and heavy social drinkers both reported feeling less impaired than the light drinkers. While they did show less overall alcohol impairment on the motor and cognitive tests, at the 30-minute interval they had similar slowing on the fine motor test as the light drinkers.

They also recovered quicker to their baseline levels, supporting the notion that they had more tolerance and can "hold their liquor" better than people who don't drink as much. However, people with AUD do not often stop drinking at four or five drinks and engage in high-intensity drinking.

At a higher dose of alcohol, they showed more than double the amount of mental and motor impairment than after they had the standard intoxicating dose.

"I was surprised at how much impairment that group had to that larger dose because while it's 50 per cent more than the first dose, we're seeing more than double the impairment," King said.