Many of you have probably experienced that alcohol has an effect on brain functions when drinking. But what are the exact effects? A recently published meta-analysis1 looks at all the randomised trials and finds that alcohol does not affect the whole central nervous system, but only specific domains. Results show that alcohol consumption specifically affects attention, automatic auditory processing, and performance monitoring. These effects are already present with 1-2 drinks, although only small.
What is already known? Alcohol reaches the brain within approximately 10 minutes. Acute effects of alcohol include amongst others impaired coordination, reaction time and speech.2
What does this study add? This is the first meta-analysis that studies the acute effects of alcohol on the human brain using EEGs. It includes 60 randomised trials with more than 2,000 participants.
The researchers analyse 60 experiments using EEG’s (electroencephalogram) to measure the effect of alcohol on the brain. They specifically look at event-related potentials, or ERP, which is the direct brain response to a sensory, cognitive or motor stimuli.
Small but significant effect with 1-2 drinks
The researchers found significant effects of alcohol on attention, automatic auditory processing, and performance monitoring. These effects were especially visible with high alcohol consumption, but small effects were already present with 1-2 drinks (BAC of 0.026%).
No effects were found for executive control and only small effects for stimulus classification.
Effects on both automatic and controlled domains
Traditionally it was thought that alcohol impairs the whole central nervous system. However, as this study shows, the effect is targeted to specific domains.
A newer theory is that alcohol does not affect the automatic responses of the brain, but only the controlled domains. This too seems to be untrue. Alcohol seems to target specific domains, but these range from automatic to controlled.
- Meta-analysis with many studies included
- Only randomised trials included
- Using EEG’s
- The average alcohol consumption in the trials was 3-4 drinks, thus more than moderate
- Relatively few older participants