How alcohol affects our mental health – and why it's so addictive
Case study / by Conor D’Andrade
Alcohol is one of the most addictive substances in the world and can have serious detrimental effects on our physical and mental health. Conor D’Andrade walks us through alcohol’s journey through the body to the brain, how it alters our neurological chemistry, and why some people literally can’t get enough.
Humans have had a long, interesting and turbulent relationship with alcohol. The first evidence we have of alcohol consumption comes from the Yellow River Valley in China, where chemical analyses on pottery from a neolithic village showed traces of a mixed fermented drink containing honey, rice, and either hawthorn fruit or grape, and dated back to 7000-6600 BCE (9000-8600 years ago, to be precise). Many researchers even suggest that the true origins of alcohol consumption date back 10 million years ago, with our distant ancestors eating partially fermented fruits that had fallen to the forest floor.
Clearly, the consumption of alcohol has played an important role to humans throughout history, but interestingly that role has been ever-changing. You only have to look at the different attitudes to drinking wine observed in Ancient Greece compared to Ancient Rome, despite the latter culture taking much inspiration from the former. But while people have been using alcohol for a variety of purposes throughout history – whether that be to celebrate, for religious rituals, or for sterilising drinking water – they certainly wouldn’t have understood why these drinks had the effect they did.
So, what is it about alcohol that makes it have such a strong effect on mood, behaviour and cognition?
A whistle stop tour of alcohol’s journey to the brain
Before we discuss how alcohol affects our brain and causes the effects many of us will have experienced at some point in our lives, let’s first look at how it gets there.
Stop 1: The stomach
The first stop for alcohol in the body is of course the stomach, where absorption of alcohol into the bloodstream begins. As time goes on it will pass into the intestinal tract, where the majority of alcohol absorption will occur in the small intestine. Because alcohol is being absorbed through the lining of the stomach and intestine, it takes time for its effects to be felt.
Stop 2: The bloodstream
The alcohol has now entered the bloodstream. The bloodstream is the body's transportation system, carrying oxygen and vital nutrients to, and carbon dioxide from, all of the cells and organs in our body so they can carry out their function. Once alcohol enters the bloodstream, its first port of call is the liver.
Stop 3: The liver
The liver is a crucial organ in our body’s processing of alcohol. Once it reaches the liver, the process of breaking it down begins immediately.
This occurs in two steps: first, a protein called ADH breaks alcohol down into the toxic acetaldehyde (ethanal). Second, this is then quickly converted by a protein called ALDH into a non-toxic substance called acetate. Acetate leaves the body in urine once it has been processed by the kidneys.
However – as you may have guessed from the fact people are able to get drunk – the liver is not able to break down all the alcohol on its first pass, and so its journey continues onto the other organs – most importantly, the brain.
The final stop: The brain
Finally, alcohol enters the brain where, depending on the amount of alcohol consumed, it carries out its often desired (as well as other less desired) effects on mood, behaviour and the body.
Glutamate and GABA: a sleepy combo
Alcohol has a huge impact on a highly important chemical in our brains called GABA.
GABA is known to reduce the activity of brain cells, making them much less likely to be active. This function is very important for processes such as sleeping, which GABA is heavily involved in.
Alcohol does not directly impact the amount of GABA in the body though. Instead, it replicates the effects of GABA by binding to GABA receptors on brain cells, preventing them from becoming active and making you feel sleepy.
GABA receptors can be activated by many other molecules than just GABA – and one of the most potent is molecules is alcohol.
But this alone is not responsible for alcohol’s potent effects, alcohol also inhibits another chemical in our brain called glutamate. If GABA can be considered the brain’s brakes, glutamate can be considered its accelerator, and alcohol has the opposite effect on these receptors.
This combination is the reason alcohol is able to have such a huge impact on humans. As brain cells in parts of the brain responsible for movement struggle to activate, the body struggles to stay coordinated and balance becomes difficult. At the same time, brain cells in parts of the brain responsible for language production struggle to activate, so speech becomes slurred and forming coherent sentences is a challenge.
This is why low levels of alcohol are relaxing, slightly more can be sleep-inducing, even more can cause loss of consciousness, and – scarily – large consumptions of alcohol can cause death as brain cells simply aren’t able to carry out their usual functions.
What makes drinking alcohol a pleasurable experience?
So, all of this explains the strong physical effects of alcohol, but what about the psychological effects? After all, people don’t start drinking because they want to fall into a chair – they start because it’s supposed to be a pleasurable experience.
The most likely cause of the pleasurable effects of alcohol comes from its effects on the release of a chemical called serotonin, and other chemicals called endorphins.
Serotonin is crucial for mediating feelings of satisfaction, optimism and happiness, while β-endorphin (beta-endorphin) causes feelings of euphoria while reducing our ability to feel pain. The combination of these effects accounts for both the joy people report when drunk, and the bruises they don’t report until the next day.
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What makes alcohol so addictive?
Being able to influence so many chemicals in our brains gives alcohol its famously potent effects. And as you may have guessed, repeatedly or aggressively exposing your brain and body to these effects can be extremely dangerous, causing detrimental psychological and physical consequences.
This is no secret, yet in England, 49% of people of drinking age consume alcohol at least once a week, 10% drink five or more days a week, and 5% of men and 3% of women aged 16-74 are estimated to be high-risk drinkers.
The problem comes down to many factors, one of the biggest being its addictiveness. And one of the most well-known causes of alcohol addiction comes from its effects on a chemical called dopamine. This protein is heavily involved in the brain’s motivation and reward system, and alcohol causes more of it to be released in the brain. But, rather than causing a feeling of pleasure, this effect can actually cause a feeling of dissatisfaction when dopamine levels drop again. This motivates people to drink more alcohol to feel satisfied again, which can quickly lead to a dependence on alcohol to achieve a feeling of normality.
The relationship between alcohol, dopamine and mental health
Dopamine is known to be a key chemical affected in many forms of mental illness, so perhaps it’s unsurprising that mental health is in fact the most influential factor in whether someone will become alcohol dependent.
We can see this in cases of so-called ‘self-medication’ for many mental illnesses where alcohol provides a temporary solution to symptoms. For example, someone with depression may find that alcohol temporarily elevates their low mood, and someone with anxiety may find that it temporarily helps them to calm down.
But, as we’ve discussed, when the effects of the alcohol stop and dopamine levels drop again, the individual is motivated to consume more to prevent their negative symptoms from returning. This is an extremely potent cocktail of emotions and behaviour that can drive someone with a mental health issue to keep drinking.