A new study led by researchers at the University of Minnesota has found that even moderate alcohol consumption can significantly change how the brain communicates within itself.
The findings, published in Drug and Alcohol Dependence, show that just a few drinks can make brain activity more localised and less connected across different regions. In simple terms, parts of the brain begin to work more in isolation rather than as a fully integrated network.
The study involved 107 healthy adults aged between 21 and 45. Over two sessions, participants were given either a drink that raised their blood alcohol level to the United States legal driving limit of 0.08 grams per decilitre or a placebo. Thirty minutes later, their brains were scanned using MRI technology.
Researchers analysed communication between 106 brain regions. They found that alcohol increased local clustering within certain areas but reduced global efficiency across the whole brain. This shift was linked to how intoxicated participants said they felt, even though their alcohol levels were similar.
One of the most affected areas was the occipital lobe, which processes visual information. Reduced connectivity here may help explain blurred vision and coordination problems linked to drinking.
The study only examined brains at rest and did not test behaviour directly. However, researchers say the findings help explain why alcohol affects thinking, emotion and self control.
Further studies are needed to explore long term effects and impacts on heavier drinkers.
