Infections increase risk of death and vaccines show significant benefit for dementia

27 July 2020

  •  Results suggest seasonal flu vaccine reduces Alzheimer’s disease risk
  • Pneumonia vaccine also linked with reduced risk of Alzheimer’s
  • Dementia and infection when admitted to hospital increases likelihood of death

Research presented at the 2020 Alzheimer’s Association International Conference indicates that people with dementia are at increased risk of death from infection, while vaccinating against flu and pneumonia could help reduce the number of dementia cases.

Three separate researchers presented their findings at the online conference.

Infections increase risk of death and vaccines show significant benefit for dementia, Alzheimer's Research UKSpeaking about the results as a whole, Dr Rosa Sancho, Head of Research at Alzheimer’s Research UK, said:
“It has become clear people with dementia, and their loved ones, have been hit particularly hard by COVID-19. The pandemic has also highlighted the serious nature of infectious diseases as well as the importance of vaccination. With dementia affecting nearly one million people in the UK alone, we must also consider the impact of infections, and preventing them, on dementia risk.

“We must continue to explore all potential avenues to reduce the number of dementia cases and this research suggests that reducing preventable infections in older people could be one helpful strategy.”

“Conferences provide an important channel for scientists to share their latest findings and this is the first opportunity that other dementia experts have to scrutinise these results. We will be better able to consider the importance of these findings when they are published in peer reviewed scientific journals.”

Seasonal flu vaccine linked to reduced Alzheimer’s risk

Researchers used US health records to look at the relationship between the influenza vaccine and dementia. The scientists compared 9,066 people and found that having a vaccine for influenza reduces the odds of developing Alzheimer’s disease, the most common cause of dementia.

Dr Rosa Sancho, Head of Research at Alzheimer’s Research UK said:
“A link between having a seasonal flu vaccine and reduced dementia risk is intriguing and this study indicates there is a beneficial impact of having one flu vaccination on dementia risk.

“It is difficult to speculate on the reasons behind this link and understanding why a seasonal flu vaccine is linked to reduced dementia risk is an important avenue for further research. This research does not mean that Alzheimer’s disease is caused by the common flu and there are potential non-biological explanations for this association, such as people who get the flu vaccine being more likely to take other steps to protect their health.

“In the UK anyone over the age of 65 is entitled to a free flu jab and anyone with queries about receiving the vaccine or worries about their health you should consult their doctor.”

Infections increase risk of death and vaccines show significant benefit for dementia, Alzheimer's Research UK

Pneumonia vaccine linked with reduced risk of Alzheimer’s

Researchers in the US have found that vaccination for infection by the pneumonia bacteria reduces the risk of dementia.

The scientists took into account the sex, age, race and education of study volunteers, as well as a genetic risk factor that could have influenced the results.

They found vaccinating against pneumonia and the flu between ages 65 and 75 was associated with a lower risk of Alzheimer’s.

Dr Rosa Sancho, Head of Research at Alzheimer’s Research UK said:
“The pneumonia vaccine protects against serious and potentially deadly infections caused by a bacteria In the UK anyone over the age of 65 is eligible to get the vaccine on the NHS.

“Exactly why this vaccine might reduce the risk of Alzheimer’s remains unclear. While some researchers have proposed a role for certain bacteria in triggering or accelerating Alzheimer’s disease processes, there is strong evidence indicating that factors other than bacterial infections are central to the development of Alzheimer’s.

“We haven’t yet seen the full findings from this research and these results will need to be taken in the context of existing research.

“It would be a bonus if a vaccine already licensed to prevent serious bacterial infections also helped reduce the risk of Alzheimer’s disease, particularly for those at increased risk of the condition. While a vaccine like this could be a cheap and relatively simple way to help reduce the number of dementia cases, we would need to see well conducted large-scale clinical trials to confirm how effective this might be.

Having dementia and infection when admitted to hospital admission increases likelihood of death

Researchers in Denmark used hospital records to investigate adverse outcomes in those who visited the hospital with an infection. They found those with dementia who visited hospital with an infection were six and a half times more likely to die in a month following the visit than those without dementia.

Dr Rosa Sancho from Alzheimer’s Research UK said:
“While we know 20% of hospital admissions of people living with dementia are for preventable conditions, this research helps to provide a clearer picture of a link between hospital admissions and adverse outcomes.

“Taken together with research into vaccines presented at this conference, this study highlights the importance of limiting preventable infections. We know dementia is caused by physical diseases in the brain and people living with dementia are more vulnerable to certain infections. Understanding the impact of hospital admissions for people with dementia will help develop approaches to limit any negative effects on their long-term health.”