Alcohol and dementia risk explained

People who drink heavily over time are more likely to develop dementia than people who don’t drink.

Research also suggests that regularly drinking large amounts of alcohol is linked to an earlier onset of Alzheimer’s disease.

The UK guideline is no more than 14 units of alcohol a week. This should be spread over at least three days, with some drink-free days.

But when it comes to brain health, the less you drink, the better. Not drinking at all is the safest option.

Drinking too much alcohol over time can damage brain cells.

Long-term heavy drinking is linked to faster brain shrinkage compared to normal ageing.

Alcohol can also damage blood vessels, reducing the flow of oxygen and nutrients to the brain. Over time, this can lead to the death of brain cells and increase the risk of conditions such as vascular dementia and Alzheimer’s.

For every 100 cases of dementia worldwide, almost half (45%) could be prevented or delayed. One of those 45 cases is linked to drinking too much alcohol in midlife.

So, if nobody drank too much alcohol, there would be one fewer case of dementia for every 100 people who develop it now.

Find out more: Addressing 14 health and lifestyle factors could prevent nearly half of global dementia cases - Alzheimer's Research UK

Long-term heavy drinking can cause alcohol-related dementia, including Korsakoff syndrome.

Korsakoff syndrome is caused by a lack of vitamin B1 (thiamine). Our bodies need vitamin B1 to turn our food into energy. Drinking lots of alcohol makes it harder for our bodies to absorb and store vitamin B1.

Without enough vitamin B1, our brain can’t produce the energy it needs to work properly.

Early treatment with vitamin B1 can improve symptoms. Without treatment, and if drinking continues, the condition can lead to permanent memory problems.

Most of what we know about dementia risk comes from observational studies, which follow groups of people over time to look for patterns in health and lifestyle.

For example, studies like Insight 46 have followed people for decades to understand how health across life is linked to brain health and later on.

This is often the most practical way to study dementia risk. Many risk factors cannot be tested in trials in a fair or ethical way. Dementia also develops over many years, so studies can take a long time to show results.

Observational studies can show when something like our diet or occupation are linked to a higher or lower chance of dementia. But they cannot prove that something directly causes dementia, or that changing it will definitely reduce risk. These studies look at patterns across large groups, not what will happen to any one person.

Randomised controlled trials give stronger evidence because participants are assigned to different groups at random. This design makes it more likely that differences in outcomes, for example our risk of dementia, are caused by the intervention, for example a diet change, rather than by other factors.

But these studies are harder to do in dementia research. They often take many years and may test several changes at once, making results harder to interpret.

Newer trials are helping to build a clearer picture of what may support brain health. No single study can give a definite answer, but it is all research findings together that help us understand what is important for our brain health and risk of dementia.