‘Repurposing’ current drugs to tackle dementia an ‘urgent priority’ – experts

More must be done to see whether existing drugs could help to tackle dementia, scientists have said after finding that a number of common treatments may affect a person’s risk.

While some new drugs are coming online to treat dementia, researchers say there is a need to see whether drugs that are currently used for other ailments could be used to alter a person’s dementia risk.

“Understanding whether drugs in current use could be re-purposed for use in dementia is an urgent priority,” academics from the University of Cambridge and the University of Exeter said after conducting a review to discover any potential treatment candidates.

They found that some vaccines, anti-inflammatory medicines and antibiotics are linked to reduced dementia risk.

Researchers set out to examine all studies which have linked commonly used treatments to dementia risk – both increased and decreased risk level.

They analysed data on 14 studies tracking the health of more than 130 million people.

Some one million cases of dementia were identified.

As well as looking at whether or not people were diagnosed with dementia, the research team also analysed prescription data and identified a number of drugs which appeared to be linked to dementia risk.

Researchers said that overall they found a “lack of consistency” between studies in identifying drugs which may modify a person’s risk of dementia.

But they did find some “candidates” which could warrant further studies.

Dr Ben Underwood, from the Department of Psychiatry at the University of Cambridge and Cambridgeshire and Peterborough NHS Foundation Trust, said: “We urgently need new treatments to slow the progress of dementia, if not to prevent it.

“If we can find drugs that are already licensed for other conditions, then we can get them into trials and – crucially – may be able to make them available to patients much, much faster than we could do for an entirely new drug.

“The fact they are already available is likely to reduce cost and therefore make them more likely to be approved for use in the NHS.”

Certain vaccines, antimicrobial treatments, anti-inflammatories and drugs to treat high blood pressure appeared to reduce a person’s risk of dementia, according to the study.

The vaccines highlighted in the study are those for hepatitis A, typhoid, hepatitis A and typhoid combined, and diphtheria.

And previous work has suggested that the BCG vaccine, which protects against tuberculosis, could also have a protective effect against Alzheimer’s disease.

Meanwhile, the large new review also suggests that antipsychotics, antihypertensives, drugs for diabetes and some antidepressants were linked to increased risk.

But the authors stressed that the finding of increased risk may be due to a number of factors – for instance a person with early dementia may be prescribed an antidepressant for altered mood so the link with antidepressants could be a “reverse causation” where dementia itself is leading to higher prescriptions for antidepressants.

Despite this, they say their study highlights some drug classes where there is “biological plausibility” for these medicines to be studied further.

“The association between antibiotics, antivirals and vaccines and decreased risk of dementia is intriguing,” they wrote in the journal Alzheimer’s and Dementia: Translational Research and Clinical Interventions.

“Viral and bacterial infectious causes of common dementias have been proposed, supported by epidemiological data linking infection to dementia risk, antiviral drugs have been identified as some of the most promising repurposed drugs for dementia and there is increasing interest in vaccination as being generally protective.

“Our findings support these hypotheses and lend further weight to these agents as being potentially disease-modifying or preventative for dementia.”

Dr Ilianna Lourida from the University of Exeter, added: “Because a particular drug is associated with an altered risk of dementia, it doesn’t necessarily mean that it causes or indeed helps in dementia.

“We know that diabetes increases your risk of dementia, for example, so anyone on medication to manage their glucose levels would naturally also be at a higher risk of dementia – but that doesn’t mean the drug increases your risk.

“It’s important to remember that all drugs have benefits and risks.

“You should never change your medicine without discussing this first with your doctor, and you should speak to them if you have any concerns.”

The NHS estimates that by 2030, the number of people with dementia in the UK will be more than one million.

Commenting, Dr Richard Oakley, associate director of research and innovation at Alzheimer’s Society, said: “If we can repurpose drugs that have already been shown to be safe and approved for use for other conditions, this could save millions of pounds and decades it takes to develop a new dementia drug from scratch, and get us closer to beating dementia.

“This research provides some initial groundwork and indicates which drugs have potential for being repurposed for dementia and should be prioritised for further investigation.

“But we can’t draw definite conclusions from this study alone. This was an observational study so more work is needed to understand the careful balance between how the drugs work, their specific doses, interactions with other drugs and the individual’s own health, and how that can impact a person’s risk of developing dementia.

“Clinical trials will help to answer some of these questions in the context of dementia.”

Dr Julia Dudley, head of research strategy at Alzheimer’s Research UK, added: “As these medications have already been shown to be safe for use in people, this could potentially speed up the process of testing in clinical trials, as well as being significantly cheaper.

“Although these findings are interesting, it is too early to say if these medications can reduce the risk of dementia. Researchers will need to confirm these findings in clinical trials and investigate how these medications could potentially protect the brain against dementia.”