Antibiotics, Vaccinations and Anti-Inflammatory Drugs Reduce the Risk of Dementia, According to Research

Antibiotics, antivirals, vaccinations and anti-inflammatory drugs are associated with a lower risk of dementia, according to a new study that analyzed health data from over 130 million people. The study, led by researchers from the universities of Cambridge and Exeter, identified several already approved and in-use medications that have the potential to be repurposed to treat dementia.

New Treatments for Dementia

Dementia is a leading cause of death and can cause profound despair for those affected and their caregivers. Despite intensive efforts, progress in identifying drugs that can slow or even prevent dementia has been disappointing. Until recently, dementia drugs were only effective for symptoms and had only a modest effect. Recently, lecanemab and donanemab were shown to reduce the build-up of amyloid plaques in the brain – a key feature of Alzheimer’s disease – and slow disease progression. However, the National Institute for Health and Care Excellence (NICE) concluded that the benefits were insufficient to warrant approval for use within the NHS.

Researchers are increasingly turning to existing medications to see if they can be repurposed to treat dementia. Because the safety profile of these medications is already known, the transition to clinical trials can be significantly accelerated. Dr. Ben Underwood from the Department of Psychiatry at the University of Cambridge and the Cambridgeshire and Peterborough NHS Foundation Trust said: “We urgently need new treatments to slow down, if not prevent, the progression of dementia. If we can find drugs that are already licensed for other conditions, we can include them in trials and, crucially, potentially make them available to patients much, much faster than we could for a completely new drug. The fact that they are already available should reduce the cost, making them more likely to be approved for use on the National Health Service (NHS).”

Relationship Between Antibiotics, Antiviral Drugs and Vaccines and a Reduced Risk of Dementia

In a study published in Alzheimer’s and Dementia: Translational Research & Clinical Interventions, Dr. Underwood, together with Dr. Ilianna Lourida from the University of Exeter, conducted a systematic review of the existing scientific literature to search for evidence of prescription drugs that alter the risk of developing dementia. Systematic reviews allow researchers to combine multiple studies where the evidence may be weak or even conflicting, to arrive at more robust conclusions. In total, the team examined 14 studies that utilized large clinical data sets and medical records, capturing data from more than 130 million individuals and 1 million dementia cases. Although they found a lack of consistency across studies in identifying individual medications that affect dementia risk, they did identify several classes of medications that were associated with an altered risk.

One unexpected finding was an association between antibiotics, antivirals and vaccines and a reduced risk of dementia. This result supports the hypothesis that common infections with viruses or bacteria can trigger dementia and the recent interest in vaccines such as the BCG vaccine against tuberculosis and a reduced risk of dementia. Anti-inflammatory medications such as ibuprofen have also been associated with a reduced risk. Inflammation is increasingly recognized as a key factor in a wide range of diseases, and its role in dementia is supported by the fact that some genes that increase dementia risk are part of inflammatory pathways. The team found inconsistent evidence for several classes of medication, with some blood pressure and antidepressant drugs, and to a lesser extent diabetes medications, associated with a reduced risk of dementia and others with an increased risk.

Fast and Efficient Drug Assessment

Dr. Ilianna Lourida from the National Institute for Health and Care Research Applied Research Collaboration South West Peninsula (PenARC) at the University of Exeter said: “The fact that a particular drug is associated with an altered risk of dementia does not necessarily mean that it causes dementia or actually helps with dementia. For example, we know that diabetes increases the risk of dementia, so anyone taking medication to regulate their blood sugar levels will naturally have a higher risk of dementia – but that doesn’t mean the medication is increasing the risk.” It is important to remember that all medications carry both benefits and risks, and medications should never be changed without first consulting a doctor, according to the researchers.

The conflicting findings may also be due to differences in how certain studies and data collection are conducted, as well as the fact that different drugs, even within the same class, often target different biological mechanisms. The UK government is supporting the development of an Alzheimer’s testing platform to quickly and efficiently evaluate drugs, including repurposed drugs that are currently used for other conditions. Researchers hope that this will help them to find much-needed new treatments for dementia and speed up the process of making them available to patients.