In a recent study published in Alcohol: Clinical and experimental studiesresearchers investigated alcohol-induced psychomotor impairments among young adult alcoholics with alcohol use disorder (AUD).
Acute alcohol poisoning leads to impairment of executive and psychomotor skills, which often results in significant damage, such as impaired driving and accidents. Studies have reported that moderate to heavy alcohol consumption (0.5 to 1.0 g per kg) increases reaction time, impairs motor coordination, and reduces performance in driving simulation and information processing.
Furthermore, alcohol consumption interferes with reasoning, judgment, and decision-making, which can impair the subjective perception of behavior. Behavioral tolerance to alcohol consumption suggests that regular consumers have decreased sensitivity to the harmful effects of alcohol. However, most previous studies evaluating alcohol-induced impairment have focused on social drinking, which limits data on acute behavioral impairment among heavy drinkers (HDs) and AUD drinkers.
About the study
In this cross-sectional study, researchers characterized psychomotor behavioral tolerance in different alcohol drinking phenotypes.
The team evaluated data from 397 participants in the Chicago Social Drinking Project (CDSP) to assess the effects of alcohol consumption on sensorimotor cognitive performance among 86 light drinkers (LD), 208 HD, and 103 AUD subjects. At the start and 30 minutes, 60 minutes, 120 minutes and 180 minutes after consuming 0.80 g per kg of alcohol [the ‘usual high’ dosage; peak breath alcohol concentration (BrAC) was 0.10 g per dL] or a placebo drink in two sessions, subjects completed the Grooved Pegboard test to assess fine motor skills and the Digit Symbol Substitution Task (DSST) to assess perceptual motor processing.
In addition, study participants completed self-report surveys on perceived impairment and completed frequency of alcohol intake and past-month cigarette and alcohol timeline follow-up interviews. Sixty AUD drinkers participated in a third single-blind experimental session with 1.20 g per kg of alcohol (the “very high” dose, peak BrAC 0.1 g per dL).
LD and HD were enrolled from 2004 to 2011, while alcoholics with AUD were enrolled from 2016 to 2019. The cohort included only healthy subjects aged 21.0 to 35.0 years who weighed between 110.0 and 210.0 pounds , and among women, only pregnant women. and non-breastfeeding women. In addition, all AUD subjects scored below 10.0 on the revised Clinical Institute Withdrawal Assessment of Alcohol Scale (CIWA-Ar) at participant screening and before each experimental session.
LDs consumed ≤6.0 drinks per week with infrequent episodes of binge drinking; HDs consumed ≥10.0 drinks per week with one to five episodes of heavy drinking per week; and AUD drinkers consumed ≥28 drinks per week (or ≥21 drinks for women) with ≥11.0 episodes of heavy drinking per month. The team excluded individuals with substance abuse (except nicotine) or mental illness and those who had positive results on breathalyzers, urine toxicology screening [other than tetrahydrocannabinol (THC)]and liver diseases. Logistic regression models were performed adjusting for age, sex, education level, family history of AUD, and cigarette and cannabis use, as well as generalized estimating equations (GEEs) and correlation tests.
Compared with light and heavy drinkers, AUD drinkers experienced fewer impairments and greater behavioral tolerance to intoxicating doses of alcohol, as demonstrated by reduced peak psychomotor impairment followed by faster cognitive recovery to baseline. Among AUD subjects who consumed 1.20 g per kg of alcohol, impairment was twice that after consumption of 0.80 g per kg of alcohol and was greater than psychomotor impairment in LD after 0.80 g per kg of alcohol consumption.
Compared to heavy and light drinkers, AUD drinkers showed worse baseline psychomotor performance on the digital symbol substitution task, which appeared to be related to their lower level of education. AUD drinkers and HD patients, compared to LDs, showed relatively greater behavioral tolerance to intoxicating levels of alcohol on the Pegboard and DSST measures, and they had a perception of being less cognitively impaired.
The results suggest that the behavioral tolerance observed among AUD subjects may be dose-dependent, as at consumption of 1.20 g per kg of alcohol they showed considerable impairment on tests.
The results showed a positive relationship between the extent of alcohol consumption and behavioral tolerance. Repeated exposure to alcohol can alter the function of neuroreceptors and neural networks, particularly glutamatergic and gamma-aminobutyric acid (GABA)-active neurotransmission, which affects psychomotor performance.
Overall, the results of the study showed that consumption of addictive amounts of alcohol strongly inhibited psychomotor function across drinker phenotypes. HDs showed faster recovery in performance with less peak impairment than LDs. However, among AUD drinkers, consumption of 1.20 g per kg of alcohol more than doubled psychomotor impairment compared with 0.80 g per kg of alcohol.
The results indicated that AUD subjects were likely to maintain higher psychomotor skills than light drinkers in moderate doses of alcohol, but when intoxicated at very large doses more similar to their typical drinking levels, their fine motor skills and working memory were significantly impaired.
Further research investigating other psychomotor responses at different alcohol doses could improve our understanding of behavioral tolerance across drinking phenotypes and its relationship to alcohol-related harm and injury.
- Didier, N., Vena, A., Feather, AR, Grant, JE & King, AC (2023) Holding your liquor: Comparison of alcohol-induced psychomotor impairment in drinkers with and without alcohol use disorder. Alcohol: Clinical and experimental studies00, 1–11. doi: https://doi.org/10.1111/acer.15080 https://onlinelibrary.wiley.com/doi/10.1111/acer.15080
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