Many of us enjoy an alcoholic drink from time to time – and it’s not only we humans who indulge. You probably know that excessive alcohol consumption can cause liver disease, but what about its effects on the brain? Some are fairly obvious – when people start falling over and slurring their words, you know something’s up – but over the longer term, the impact of alcohol can be more insidious.
Short-term effects of alcohol
Speech
One of the first signs that someone has had one too many is when you can’t understand a word they’re saying. American Addiction Centers points out that this effect is typically only seen once blood alcohol concentration (BAC) reaches 0.1 percent – the legal driving limit in the US for those over the age of 21 is 0.08 percent. There are a few different things that come together to cause this effect.
One generalized effect that alcohol has on the brain is that it alters the balance of two key neurotransmitters: glutamate, which is excitatory; and gamma-aminobutyric acid (GABA), which is inhibitory. When there’s more GABA and less glutamate around, neurons fire more slowly and everything just kind of takes longer – this is why alcohol has a sedative effect and one reason why you may experience “hangxiety” after a heavy night as these levels restabilize.
When this imbalance affects areas responsible for motor control, it impairs voluntary movement of the muscles in the tongue and face, making it difficult to form words properly.
A 2015 study also pointed to the role of alcohol in altering the function of Purkinje neurons in the cerebellum, which are vital for movement and coordination. Using a detailed computer model, researcher Michael D Forrest showed how alcohol can inhibit sodium-potassium pumps on the surface of these neurons, meaning that the balance of sodium and potassium ions is upset and the cells can’t function properly.
Alcohol can also directly affect the areas of the brain responsible for language processing and speech production – so if your friend is no longer making sense to you, chances are your attempts to communicate back won’t be faring much better.
Balance
That leads us neatly to the next most obvious sign that someone’s been drinking – they’re staggering around the place, doing their best impression of a newborn foal, and quite possibly falling over.
Just as messing with the function of motor neurons can affect speech, it can also affect walking and coordination. The cerebellum is again key to this, as it controls both movement and the coordination of visual and spatial information that helps keep us upright relative to our surroundings.
This effect tends to be seen once someone’s BAC hits around 0.18 to 0.25, well past the point of legal “intoxication”. At this stage, alcohol is impacting pretty much every part of the brain.
Memory
Your drunken antics may well gift your friends with several choice memories they can laugh about later, but as for your memory? It’s probably not going to be working so well the morning after.
Losing chunks of time to alcohol is often colloquially referred to as getting “blackout drunk”. People may arrive in a new location with no memory of having traveled there – even if that travel involved an airplane – or, more sinisterly, end up involved in dangerous situations with no memory of what has happened to them.
It’s thought that alcohol’s effect on the hippocampus is what causes this, as this region of the brain is central to the formation of new memories. It’s thought that alcohol impairs this process – it’s not so much that we “forget” what’s happened, more that we never recorded those memories in the first place.
A series of… questionable experiments in the 1960s and 70s helped scientists understand how blackouts happen. Researcher Donald Goodwin recruited people with alcohol addiction – some with a history of blackouts – and gave them large quantities of booze before performing memory tests. Needless to say, there’s no way this would get past an ethics committee today.
Inhibitions
That memory loss can sometimes be a blessing in disguise, though, when we consider our final short-term effect of drinking. Alcohol impairs our judgment and lowers our inhibitions, making us say and do things that we’d ordinarily never contemplate.
In this case, the region of the brain that alcohol is impairing is the prefrontal cortex, which controls reasoning, judgment, and all those higher cognitive skills that set humans apart from other species. Sober humans, anyway.
Research does not go so far as to suggest that alcohol can alter your personality completely; it might just make you more likely to speak your mind in an unfiltered way, which may not go down so well with the people you’re relying on to drive you home.
Long-term effects of alcohol
So far, we’ve focused on things that could affect any one of us after only a few drinks. When alcohol use becomes chronic, with high-level consumption over a long period of time, it’s possible to see permanent damage to the brain.
Addiction
While lots of people consume alcohol without developing a dependency, alcohol is an addictive substance.
As the National Institute on Alcohol Abuse and Alcoholism explains, there are three main mechanisms that are thought to drive the development of alcohol use disorder (AUD).
- Alcohol activates the brain’s reward circuitry, mediated by dopamine, which can drive some people towards increased consumption.
- Drinking alcohol can become a habit where the decision to drink is no longer under conscious control, thus making it very difficult for people to stop.
- Alcohol temporarily relieves pain and negative emotions by decreasing activity within the amygdala, relieving stress. When this effect is lifted and the alcohol has left a person’s system, they may be driven to drink more and more to try and recapture this state.
Wernicke’s encephalopathy
One condition that people with AUD are almost uniquely predisposed to is Wernicke’s encephalopathy, caused by a deficiency in vitamin B1, AKA thiamine.
Thiamine is essential to a number of metabolic processes within nerve cells, and without enough of it around the cells can die. Alcohol prevents thiamine from being absorbed, processed, and stored correctly.
The major signs of Wernicke’s encephalopathy include an altered mental state, problems with gait – which may even result in losing the ability to walk – and eye movement disorders, especially nystagmus.
If untreated, Wernicke’s encephalopathy can be fatal. A large percentage of survivors – up to 85 percent – in cases where treatment is not given or is delayed will develop a chronic complication called Korsakoff syndrome.
Korsakoff syndrome
Korsakoff syndrome is a chronic condition that often follows episodes of Wernicke’s encephalopathy and is commonly seen in people who’ve had AUD for a long time. Together, the two conditions are sometimes called Wernicke-Korsakoff syndrome (WKS).
The cardinal symptom is short-term memory loss, although some individuals may experience issues with long-term memory too. The peculiar part is that many people with Korsakoff syndrome are unaware they have it, and they’re generally able to continue social behaviors like holding conversations just as they were before.
The effects can be permanent, and over time nerves controlling other bodily functions can be affected. Eventually, patients can start to experience blood pressure and cardiovascular issues. About 10 to 20 percent of people with advanced WKS will fall into a coma and die, according to the National Organization for Rare Disorders.
Can brain damage from alcohol be reversed?
WKS is at the extreme end of the damage that alcohol can do to the brain and is typically seen in people who have had AUD for a considerable period of time. However, even one episode of binge drinking can have a marked (if usually temporary) impact on the brain.
“There is no designated ‘safe’ level of drinking,” addiction specialist Dr Amanda N. Donald said in an article for Northwestern Medicine’s HealthBeat.
The human body is resilient, and the brain can recover if alcohol consumption is stopped. One recent study found that in the brains of participants who had experienced AUD for a number of years, their cortical thickness had recovered to a similar level to control participants after 7.3 months of abstinence. Another found that just 18 days of sobriety was enough to improve cognition.
If you’re worried about your own alcohol use, or that of a friend or family member, help and support are available.
The content of this article is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of qualified health providers with questions you may have regarding medical conditions.
All “explainer” articles are confirmed by fact checkers to be correct at time of publishing. Text, images, and links may be edited, removed, or added to at a later date to keep information current.
Source Link: What Does Alcohol Actually Do To Your Brain?
