2024-08-02 14:35:39
Shingles is a painful disease. A vaccination can protect older people in particular from it – and may also be effective against dementia.
It is estimated that around 1.8 million people in Germany live with dementia. The causes of this neurological disease are not yet fully known. However, infections with certain viruses and bacteria are suspected of causing dementia later in life.
A new study by researchers at Oxford University in England has now found that a vaccination that actually protects against shingles could also delay the onset of dementia. The study was published in the journal “Nature Medicine”.
Shingles, also known as herpes zoster, is a painful disease that affects many older people. It is caused by the so-called varicella zoster virus (herpes virus). This virus can flare up again in adulthood in people who had chickenpox as a child. The Standing Committee on Vaccination in Germany currently recommends vaccination against chickenpox for small children and immunization against shingles for adults. You can find out more about the shingles vaccination here.
Background to the study: In the USA, as in Germany, there are two vaccines against shingles, the live vaccine Zostavax and the inactivated vaccine Shingrix. The researchers of the current study took advantage of the fact that in October 2017, the USA switched from Zostavax to the current vaccine Shingrix within a few days. The reason was that in clinical trials, the live vaccine Zostavax had achieved a significantly worse protective effect against shingles than the new vaccine Shingrix.
This change enabled the researchers to compare the risk of dementia in a Shingrix group with people who had received Zostavax. Each group studied included more than 100,000 people. The British researchers used the electronic health data network in the USA for their study.
In Germany, the herpes zoster live vaccine Zostavax has also not been recommended as a standard vaccination by the STIKO since 2018 due to its limited effectiveness and limited duration of action. In addition, the live vaccine is not suitable for vaccinating people with weakened immune systems.
The result: In the six years following vaccination, people vaccinated with Shingrix developed dementia an average of 164 days later. However, the vaccination could not completely prevent the outbreak of the disease. The positive effects were observed in both sexes, but more pronounced in women than in men.
But in a second analysis, the researchers found that even with the old vaccine, dementia was delayed by 135 to 260 days (14 to 27 percent). Shingrix could therefore cause people to develop dementia a total of 424 days later.
Previous studies had already shown that a shingles vaccination (at that time with the live vaccine) reduced the likelihood of developing dementia in the following years. However, neither the previous nor the current study provide an explanation as to how this protection could come about.
The reasons for the risk reduction are unclear, explains the study’s lead author, Maxime Taquet. However, it is possible that herpes zoster infections contribute to dementia, so the vaccine that protects more effectively against the virus will also be more effective at preventing dementia, says Taquet.
Whether viral infections generally increase the risk of developing a neurodegenerative disease has been a topic of debate for some time. One of the reasons for this was a large study from last year in which 45 different viruses were identified as possible triggers of diseases such as dementia or Parkinson’s.
Hartmut Hengel, head of the Institute of Virology and head of the consultancy laboratory for varicella zoster viruses at the University Hospital of Freiburg, presents a possible mechanism in the “Süddeutsche Zeitung”. According to him, the varicella zoster virus nests in certain human nerve cells. The reactivation of the virus, as is the case with shingles, can then lead to inflammatory reactions in surrounding blood vessels – and even trigger a stroke.
When a stroke occurs, the brain no longer receives the correct blood supply. Dementia can also be caused by circulatory disorders in the brain, says the expert. This is known as so-called vascular dementia. Therefore, this is at least one conceivable mechanism of action with consequences for the cerebrum, says Hengel.
However, the researchers themselves point out that the data only show a correlation between the timing of vaccination and a delayed onset of dementia. Therefore, the data do not allow any conclusions to be drawn about a direct protective effect of the vaccine on dementia.
Before a clear answer can be found to the question of whether the shingles vaccination can prevent or delay dementia, further studies are necessary, say the researchers.
But despite the remaining unanswered questions, the authors agree: A vaccination against shingles makes sense – if only to protect yourself from this painful disease in old age.