New research examining health data from over 130 million individuals shows that antibiotics, antivirals, vaccinations, and anti-inflammatory medication are associated with reduced risk of dementia.
The study, led by researchers from the University of Cambridge and NIHR PenARC (at the University of Exeter), identified several drugs already licensed and in use that can potentially be repurposed to treat dementia.
Dementia is a leading cause of death in the UK and can lead to profound distress in the individual and among those caring for them. It has been estimated to have a worldwide economic cost over 1 trillion US dollars.
Despite intensive efforts, progress in identifying drugs that can slow or even prevent dementia has been limited. Until recently, dementia drugs only helped symptoms and have a limited effect. Recently, lecanemab and donanemab have been shown to reduce the build-up in the brain of ‘amyloid plaques’ – a key characteristic of Alzheimer’s disease – and to slow down progression of the disease. However,the National Institute for Health and Care Excellence (NICE) concluded that the benefits were insufficient to justify approval for use within the NHS.
Scientists are increasingly turning to existing drugs to see if they may be repurposed to treat dementia. As the safety profile of these drugs is already known, the move to clinical trials can be much faster.
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.”
In a study published today in Alzheimer’s and Dementia: Translational Research & Clinical Interventions, Dr Underwood, together with Dr Ilianna Lourida from NIHR PenARC and the University of Exeter, led a ‘systematic review’ of existing scientific literature to look for evidence of prescription drugs that changed the risk of dementia. Systematic reviews help researchers combine multiple studies, even if the evidence is weak or conflicting, to reach stronger conclusions.
In total, the team examined 14 studies that used large clinical datasets and medical records, capturing data from more than 130 million individuals and 1 million dementia cases. Although they found a lack of consistency between studies in identifying individual drugs that affect the risk of dementia, they identified several drug classes associated with altered risk.
One unexpected finding was an association between antibiotics, antivirals and vaccines, and a reduced risk of dementia. This finding supports the hypothesis that common dementias may be triggered by viral or bacterial infections. This supports recent interest in vaccines, such as the BCG vaccine for tuberculosis, and decreased risk of dementia.
Anti-inflammatory drugs such as ibuprofen were also associated with reduced risk. Inflammation is increasingly being seen to be a significant contributor to a wide range of diseases, and its role in dementia is supported by the fact that some genes that increase the risk of dementia are part of inflammatory pathways.
The team found mixed results for several types of drugs—some blood pressure medications and antidepressants, and to a lesser extent, diabetes drugs, were linked to a lower risk of dementia, while others were linked to a higher risk.
Dr Ilianna Lourida, PenARC Dementia Capacity Building Research Fellow at the University of Exeter, said:
“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.”
Conflicting evidence may reflect differences in how studies were conducted and how data was collected, as well as the fact that even similar drugs can work in different ways.
The UK government is supporting the development of an Alzheimer’s trial platform to evaluate drugs rapidly and efficiently, including repurposed drugs currently used for other conditions.
Dr Underwood added:
“Pooling these massive health data sets provides one source of evidence which we can use to help us focus on which drugs we should try first. We’re hopeful this will mean we can find some much-needed new treatments for dementia and speed up the process of getting them to patients.”