Older adults who receive a high-strength flu jab may have a significantly lower risk of developing Alzheimer’s disease, a major study suggests.
Researchers found those given the vaccine had a 55 per cent lower risk of the condition, compared with a 40 per cent reduction among those receiving a standard jab.
The findings, based on nearly 200,000 adults aged 65 and over and published in Neurology, add to growing evidence that routine vaccinations may help protect the brain as we age.
Previous studies have suggested that getting a flu shot each winter could help reduce the risk of dementia.
There is no suggestion that catching flu causes dementia; rather, scientists believe the benefit comes from vaccination later in life.
Vaccines – given to more than 16 million people in England last winter – may help the ageing immune system reduce inflammation, a key driver of brain damage linked to dementia.
As we get older, cells become more prone to damage and release chemicals that drive chronic inflammation, while the body becomes less able to repair itself.
This increases the risk of illnesses such as cancer, dementia and heart disease.
Scientists believe the vaccines may help the ageing immune system reduce inflammation that contributes to brain damage linked to dementia
Everyone experiences dementia differently. Use this checklist to help you make a note of your symptoms before you talk to your GP.
Scientists are increasingly exploring whether it may be possible to slow or even reverse this biological ageing process.
Vaccines such as the high-dose flu jab may help strengthen the ageing immune system and dampen inflammation, potentially lowering dementia risk.
The protective effect appeared stronger in women, though the reason for this is not yet clear.
‘At age 65, the immune system becomes less effective at fighting infection,’ said Dr Paul Schulz, professor of neurology at McGovern Medical School at UTHealth Houston and director of the Neurocognitive Disorders Centre. ‘This is why a high-dose vaccine is recommended for adults aged 65 and over.’
Previous research from his team suggested that getting any flu shot could lower Alzheimer’s risk. This new study shows that a higher dose may offer even greater protection.
Dr Avram Samuel Bukhbinder, a corresponding author and neurology fellow at Massachusetts General Hospital, said: ‘Our findings suggest that selecting the high-dose vaccine could be an easy, safe, and widely available way to help protect the brain as we age.’
The findings are particularly relevant in the UK, where more potent flu vaccines are already part of routine care.
As of the most recent flu season, the Joint Committee on Vaccination and Immunisation (JCVI) recommends ‘enhanced’ vaccines for adults aged 65 and over to counteract the natural weakening of the immune system.
This includes the high-dose inactivated influenza vaccine (IIV-HD), such as Efluelda, which is four times stronger than standard vaccines.
Another option commonly used in the UK is the adjuvanted vaccine (Fluad), which contains an added ingredient to boost the immune response and provide longer-lasting protection.
The JCVI also recommends the recombinant vaccine (Supemtek), an egg-free jab considered equivalent in providing enhanced protection.
These vaccines are offered free on the NHS to those aged 65 and over, generally from October each year.
While flu vaccination has long been recommended for older adults, this research highlights the added benefit of the high-dose shot, not just for preventing influenza but also for reducing the risk of Alzheimer’s.
The study was observational, meaning it shows an association rather than proof that the vaccine prevents Alzheimer’s. Factors such as overall health and lifestyle could also influence results.
In England, flu vaccine uptake for those aged 65 and over is consistently high, with 74.9 per cent vaccinated in the 2024–25 season – close to the 75 per cent target set by the World Health Organisation, although uptake in 2023 was higher at 79 per cent.
Alzheimer’s is the most common form of dementia in the UK, accounting for 60 to 80 per cent of cases – roughly two in three people with the condition.
The progressive disorder is caused by abnormal protein build-up in the brain, known as plaques and tangles, which gradually destroy brain cells.
