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General anaesthetic and the risk of dementia

It's not clear whether general anaesthetics increase dementia risk. If you're worried about surgery, it can help to talk to your doctor.

Can general anaesthetics increase the risk of dementia?

There is currently no strong evidence to say that general anaesthetics increase a person’s risk of developing dementia.

Some older people undergoing surgery show memory and thinking problems afterwards. This is known as post-operative cognitive dysfunction and patients usually recover quickly.

In rare cases, these problems sometimes persist – and may even lead to a diagnosis of dementia. This can happen when someone has underlying or undiagnosed memory and thinking problems.

This has led to questions about whether the general anaesthetic used during surgery can cause dementia, but there is no scientific evidence of this. Researchers are looking at whether it may increase a person’s risk of developing dementia. 

How to reduce the risk of dementia

A lifelong approach to good health is the best way to lower your risk of dementia.

There are some lifestyle behaviours with enough evidence to show that changing them will reduce your risk of dementia.

Reduce your risk of dementia

Can having surgery increase dementia risk?

Apart from the general anaesthetic, surgery itself tends to carry higher risks of complications for older people. One reason for this is that as we age, our bodies may be less able to protect themselves from infection or repair damage. Doctors sometimes measure this as ‘frailty’.

Studies have shown that older, more frail patients are at higher risk of complications from surgery. They are also more likely to have short-term problems with memory and thinking, and longer stays in hospital after surgery.

There is also evidence that surgery can result in inflammation, which is associated with cognitive decline. Some researchers think that cell damage from surgery is more likely to trigger inflammation in older brains than general anaesthetics. Others think that some general anaesthetics could prevent brain cells from repairing the damage.

In the brain, damaged cells signal to nearby ‘repair cells’. These repair cells trigger the immune system to protect and repair the damage. This process is known as inflammation and is beneficial. However, it can be less controlled in the brains of older people and lead to too much inflammation which further damages brain cells.

Studying the effect of general anaesthetics on the brain is difficult. Dementia can develop very slowly, and few studies follow people for a long enough period of time. The studies that do exist have mixed results. Some studies showed no association between general anaesthetics and dementia. Others showed a small increase in dementia risk.

Even in studies that showed an association, it doesn’t mean the general anaesthetic caused the increase in dementia risk. It may have something to do with the condition that required the surgery, rather than the general anaesthetic itself.

For example, issues with heart and blood vessels increase the risk of dementia, and a person with these issues is also more likely to need surgery.  

How general anaesthetics may be related to short-term changes in thinking and memory has also been investigated. One study found that some types of anaesthesia may lead to faster recovery from short-term changes in the brain of older people. This result indicates general anaesthetic may play a role in thinking and memory problems immediately after surgery.

Some studies in animals have found that certain types of general anaesthetics lead to increased levels of toxic clumps of amyloid and tau proteins in brain cells. These proteins are thought to cause damage to brain cells in Alzheimer’s disease.

Damage to brain cells could also be caused by low levels of oxygen in the blood and lower body temperatures caused by anaesthesia. Some studies also suggest that anaesthesia may make existing underlying dementia mechanisms worse, particularly in people at increased genetic risk of the condition.

Further reading

What to consider when a person with dementia is preparing to go into hospital.

Find out more

How a hospital in Norfolk is helping people with dementia feel at ease before surgery.

Find out more

Learn all you need to know about general anaesthesia.

Find out more

Last reviewed: December 2023

Next review: December 2025