The Australian relationship with alcohol is complicated. It’s a colourful thread woven into the fabric of our society.
As a chemical, alcohol is a very simple molecule, but its effects on the brain are quite complex. And different people respond differently to alcohol in different situations.
Consumed orally, alcohol enters the bloodstream through the gastrointestinal tract. The amount that is absorbed varies from individual to individual depending on their genetic make-up and any medical conditions. It also varies depending on whether there is food in the gut, since this can reduce absorption into the bloodstream.
The size of the person and ratio between muscle and fat will also affect the rate at which the person’s blood alcohol concentration rises with consumption. Because alcohol is water-soluble, if two people weigh the same, the person with more muscle and less fat will have a lower blood alcohol concentration than somebody with more fat and less muscle after consuming the same amount of alcohol.
Once in the bloodstream, alcohol affects many of our body’s organs, but the nervous system (including the brain) is key in terms of behavioural effects. Alcohol acts as a central nervous system depressant. This means it slows down the rate at which brain cells and other nerves in the body communicate with one another.
Some people are surprised to find out alcohol is a central nervous system depressant since a low dose of alcohol can often lift one’s mood and act as a social lubricant.
The reason alcohol acts as a social lubricant is because it reduces the functioning of the limbic system of the brain. The limbic system is responsible for producing emotions that drive anxiety and fear. As such, we tend to feel a little less socially awkward after a few drinks.
In addition, alcohol reduces the functioning of the pre-frontal cortex – the part of the brain responsible for higher-order cognitive processing (including reasoning and judgement). This leads people to be less inhibited and more impulsive after they have had a few drinks.