It’s well-known that excessive drinking can damage your health and organs including the liver, heart and gut. But what about the brain – what harm can alcohol do to it, and can going sober improve cognitive function?

As millions of people embark on Dry January, where they give up alcohol for a month, Dr Peter Rice, chair of the Institute of Alcohol Studies, says: "Alcohol profoundly affects the brain, both in the short and long-term.

"For many people who consume alcohol – not just heavy drinkers – reducing or stopping alcohol intake often results in enhanced concentration and better mental health, all of which indicate improved brain health."

Dr Richard Piper, CEO at Alcohol Change UK, says: "Alcohol is a chemical that can bring about big changes in the complex functions of the human brain.

"The good news is that by cutting down our alcohol consumption or by taking a break, such as the Dry January challenge, we can realise some immediate health benefits, like reduced blood pressure and heart rate, while improving our hydration and sleep quality, all of which can help our brains."

Here’s how alcohol affects the brain, and how sobriety can reverse those effects…

1. Changes in dopamine, the brain’s feel-good hormone

In the short-term, drinking alcohol triggers the release of extra dopamine, the hormone that makes us feel happier, less inhibited and not as sensitive to physical or emotional pain, explains Piper.

"So it’s no surprise that once we start drinking, we often want to carry on or become reliant on its immediate effects when looking to de-stress or feel better," he says. "Yet, if we drink often or heavily, our body and brain can become used to these dopamine boosts and start to make less dopamine to compensate, leading us to become dopamine-deficient."

If you stop drinking, Piper suggests it can help in the early days to find new ways to reward or treat yourself that don’t involve alcohol, like going for a run or setting yourself a new challenge.

"Initially, we may feel a little grumpy when we stop drinking and this is completely normal," he says. "That’s because dopamine is still depleted and our body is replacing vitamins and minerals."

Finding new reward pathways when you first stop drinking "will help to release these chemicals in your brain in a healthier, more positive and sustainable way," he explains. And if you stay sober, dopamine levels should eventually level out again.

2. Memory changes

Piper says heavy drinking can lead to alcohol-related brain damage (ARBD) and increased risk of dementia, Alzheimer’s and amnesia. "ARBD can manifest itself in a variety of ways, such as changes in personality, as well as problems with thinking, decision-making, mood, memory and learning," he explains.

But after around three weeks of not drinking, he says: "The brain boosts we may notice include improvements in mood and memory, particularly our short-term memory. We might also find that we can retain information for longer, are less forgetful and more able to focus our attention."

And Rice adds: "For daily heavy drinkers in the medium to long-term, stopping or reducing alcohol intake can reverse some harms such as impaired memory and orientation.

"Unfortunately, for some people the extent of brain cell loss means recovery isn’t complete."

3. Changes to brain shape

A 2022 study of 36,678 middle-aged and older men and women found that consuming just one alcoholic drink daily (or two units of alcohol) was associated with changes in grey matter and white matter volumes in the brain.

"Long-term drinking can cause brain shrinkage, memory decline, and increased dementia risk, with brain imaging studies showing shrinkage even at moderate levels of drinking," warns Rice.

And Piper explains that as alcohol is a diuretic, meaning it makes drinkers pass more urine, it can lead to dehydration which can also affect the brain. "This can cause brain cells to shrink and die," he says. "Longer-term, drinking too much alcohol can change the way the brain works and its physical shape and structure."

However, when you stop drinking alcohol, especially for a long time, the brain starts to repair and rebuild damaged neural connections. The Alzheimer’s Society in the UK says: "If a person with ARBD stops drinking alcohol and receives good support, they may be able to make a partial or even full recovery."

4. Changes to vitamin B1 levels

A lack of vitamin B1 (thiamine) can also play a part in changing the shape and structure of the brain, and Piper explains: "Alcohol makes it hard to absorb some vitamins, including the all-important vitamin B1, which is a building block of the brain."

But recovery is possible, and he says: "The outcomes for people who stop drinking and who receive high-dose vitamin B1 treatment can be very good, with much of the damage to the brain being reversed."

5. Mental health changes

Many people drink to try and help manage stress, anxiety, depression or other mental health problems. However, the effects are short-lived and the long-term negative consequences of drinking a lot can be harmful and lead to the worsening of low mood and anxiety symptoms.

Piper explains that depression and heavy drinking are mutually reinforcing – meaning that either one increases a person’s chances of experiencing the other. But he stresses: "Managing your alcohol intake is one way of reducing your risk of developing depression."

"If you’re worried about your drinking or keen to understand your relationship with alcohol may be impacting your health and wellbeing, it’s best to speak to your GP."

If you are affected by any of the issues raised in this article, you can visit Ask About Alcohol.