Preventing dementia: what’s the evidence?

In a blog for non-medical people, James Garrard, Specialist Registrar in Geriatric Medicine, looks at the evidence on various drug and non-drug approaches to try and prevent dementia.

Take-home points Many people look for ways to reduce their risk of dementia, which affects 1 million people in the UK. Cochrane evidence on drug and non-drug approaches to try and prevent dementia suggests that: aspirin and statins do not appear to reduce the risk of developing dementia, and vitamin supplements probably do not help either; blood pressure medications probably do not help reduce the risk of dementia in people who have had a stroke. It is unclear whether they are helpful for reducing the risk in other people; interventions to target more than one dementia risk factor do not appear to help; there is currently a lack of research following what happens to people taking part in studies for more than ten years. It is thought that up to 1 in 3 dementia diagnoses could be prevented. While some of the things known to increase the risk of dementia can’t be changed (such as age), there are up to 12 things we can potentially do something about – including drinking less alcohol, stopping smoking, and maintaining a healthy weight. 

From both personal and professional experience, I have witnessed the awful effects of a dementia diagnosis on both the person with dementia and their loved ones. Initially, dementia causes a decline in memory and thinking, but as it progresses it can affect almost any bodily function such as mobility, swallowing, speech, bowel, and bladder control. The financial impacts are also huge. Dementia costs the UK economy £34 billion annually, most of which is paid by the people affected with dementia for support and care.

Dementia currently affects around 1 million people in the UK, but the number of people living with dementia is expected to double by 2050. There are many types of dementia, the commonest being Alzheimer’s Dementia and Vascular Dementia which account for over three-quarters of dementia diagnoses.

What do we know about ways to reduce the risk of dementia?

The diagnosis of dementia often comes when symptoms are at a relatively early stage, triggering fear and anxiety about what the future holds. I have been asked many times by relatives of people with dementia ‘what can I do to prevent me getting dementia in the future?’. Below, I look at the Cochrane evidence on taking blood pressure medications, vitamin and mineral supplements, aspirin, brain training, intensive management of Type 2 Diabetes, and interventions to target more than one known dementia risk factor.

Taking medication for high blood pressure is common – does this help to prevent dementia?

At present, it is very uncertain whether treating high blood pressure may slightly improve memory test results but not change the risk of developing dementia, in up to 5 years of follow-up. This is according to the Cochrane Review Pharmacological treatment of hypertension in people without prior cerebrovascular disease for the prevention of cognitive impairment and dementia (May 2021).

The use of blood pressure lowering drugs following a diagnosis of stroke or mini-stroke (TIA) probably makes little or no difference in the rate of dementia diagnosis within 1 to 4 years follow up, finds the Cochrane Review Blood pressure‐lowering treatment for preventing recurrent stroke, major vascular events, and dementia in patients with a history of stroke or transient ischaemic attack (July 2018).

Blood pressure lowering drugs have other benefits though: they reduce the risk of other vascular events (such as heart attacks) and probably reduce the risk of recurrent stroke, although they probably have little or no effect on the risk of dying.

Some big claims are made about vitamin and mineral supplements, but can they really help prevent dementia?

The use of Vitamin B (B6, B12 and Folic acid) probably makes little to no difference to memory or thinking skills in patients with mild cognitive impairment, according to the Cochrane Review Vitamin and mineral supplementation for preventing dementia or delaying cognitive decline in people with mild cognitive impairment(November 2018). There was no evidence on whether taking Vitamin B affects the risk of developing dementia.

Vitamin E supplements probably do not change the risk of people with mild cognitive impairment developing dementia over three years.

Vitamins and mineral supplements are not routinely prescribed by a doctor (other than for deficiency), so a decision to buy vitamins could be expensive and add to the burden of taking extra tablets. Supplements can cause side effects, they can interact with prescribed medication and some supplements can cause harm if too many are taken. If you take supplements, do tell your doctor what you are taking.

An existing blog, Preventing dementia: do vitamin and mineral supplements have a role? explains that there is no reliable evidence supporting any particular vitamin or mineral supplement for dementia prevention.

Do aspirin and non-steroidal anti-inflammatory medications help prevent dementia?

Evidence indicates that taking a low-dose aspirin does not change the risk of developing dementia. This is according to the Cochrane Review Aspirin and other non‐steroidal anti‐inflammatory drugs for the prevention of dementia (April 2020) which included one study of 19,000 healthy people aged over 70, followed up for nearly 5 years.

The review also found that other anti-inflammatory medications probably do not reduce the risk of dementia. Both aspirin and non-steroidal anti-inflammatory medications were associated with higher rates of bleeding from the gut, and the studies were all stopped early because of a lack of benefit and risk of harm.

Brain training tools and apps are becoming more widely available, but do they work to prevent dementia?

There is currently a lack of evidence as to whether computerised brain training helps to improve aspects of memory and thinking speed, and there is no evidence at the moment about whether this helps to prevent dementia, finds the Cochrane Review Computerised cognitive training for preventing dementia in people with mild cognitive impairment (March 2019).

Brain training interventions rely on access to technology, computer literacy and internet connection, which may limit who can take part in them. These practical barriers to taking part will typically affect older people and people from lower socio-economic backgrounds more, where the risk of dementia is higher.

Alzheimer’s Research UK suggests that doing things you enjoy – and are likely to carry on doing – is important to keep your brain active. This may in the meantime help to boost ‘cognitive reserve’ and help the brain to cope for longer.

Can statins help to prevent dementia?

There are lots of other potential reasons for people to be prescribed statins. The Cochrane Review Statins for the prevention of dementia (January 2016) looked at the use of statins in 26,000 patients aged 65 and over, or patients with a history of cardiovascular disease. Statins probably make little or no difference to the rate of dementia diagnosis, nor do they lead to differences in the results of memory testing. In 3 years of follow up, the risk of side effects was low, and few people stopped taking their statin.

Does a more intensive approach to managing type 2 diabetes affect the risk of developing dementia?

For patients with type 2 diabetes, a more intensive treatment regime probably makes little to no difference to the rate of dementia diagnosis or to performance on memory tests, in up to 5 years of follow up. The intensive treatment regime probably increases the risk of low blood sugar (hypoglycaemia), which can be a major problem for patients with diabetes. This is according to the Cochrane Review Effect of the treatment of Type 2 diabetes mellitus on the development of cognitive impairment and dementia (June 2017).

Could an intervention to target two or more dementia risk factors prevent the onset of dementia?

Current evidence indicates that interventions targeting multiple different risk factors (for example, increasing physical activity plus taking medication to reduce blood pressure or cholesterol) make little to no difference to the rate of dementia diagnosis, finds the Cochrane Review Multi‐domain interventions for the prevention of dementia and cognitive decline (November 2021).

It is unclear whether people managed to stick to the interventions, but there were no reported harmful effects.

People showed a small improvement in detailed tests of cognitive function, but this could have been explained by them receiving brain training as part of the intervention. In people with an increased genetic risk of dementia (ApoE4 gene), the improvement in memory testing scores was greater.

So, what can you do to reduce your risk of dementia and where can you look for help?

Overall, there appears to be a lack of evidence to support any one intervention or medication to prevent dementia. Currently, it is unknown whether starting any of the tablets or interventions mentioned in this blog in mid-life reduces dementia risk in the long-term, as there is a lack of research for long enough.

We know that the risk of dementia increases with age, as well as with many medical, sociological, and psychological factors. In a previous blog Behind the headlines: can one in three dementia cases be prevented? Kirsty Marais from Alzheimer’s research UK discussed the 12 risk factors which can be changed, accounting for up to a third of dementia cases.

The 12 risk factors are:

  • hearing loss
  • low education
  • smoking
  • depression
  • lack of physical activity
  • social isolation
  • high blood pressure
  • obesity
  • diabetes
  • excessive alcohol consumption
  • head injury
  • air pollution.

The NHS website talks through some ways to try and address some of the changeable risks of dementia. Alzheimer’s Research UK  discusses three simple rules to try and protect our brains:

  1. Love your heart – trying to maintain a healthy diet, good blood pressure control and regular activity or exercise
  2. Stay sharp – keeping your mind active can help improve your brain reserve, it is important to consider doing something you enjoy
  3. Keep connected – keeping connected to the people around us is another good way to give back to our brains, and can make us feel happier and healthier in general.

Join in the conversation on Twitter with @jamie_garr @CochraneUK or leave a comment on the blog.

Read more of our dementia blogs.

Please note, we cannot give medical advice and do not publish comments that link to individual pages requesting donations or to commercial sites, or appear to endorse commercial products. We welcome diverse views and encourage discussion but we ask that comments are respectful and reserve the right to not publish any we consider offensive. Cochrane UK does not fact check – or endorse – readers’ comments, including any treatments mentioned.

References (pdf)

Dr James Garrard has nothing to disclose.



Preventing dementia: what’s the evidence? by James Garrard

is licensed under a Creative Commons Attribution-NoDerivatives 4.0 International

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