A shingles vaccine could delay dementia
Dementia is a feared age-related disease that is set to affect more people in the future. Researchers now have indications that a relatively new shingles vaccine not only prevents shingles but could also halt dementia.
The use of the shingles vaccine Shingrix has led to a decrease in dementia cases among those aged 65 and over in the USA, according to researchers at the University of Oxford. The effect was observable in both women and men, but was stronger in women, the researchers write in their results published in the journal "Nature Medicine".
The introduction of the new Shingrix vaccine, used in the USA since 2017, provided a good starting point for research. Previously, it was only possible to compare the side effects of shingles vaccines in those who were vaccinated with those who were not. Because it is known that people who get vaccinated tend to live healthier lives overall, these research results were prone to errors and therefore only partially meaningful. However, with the new approval of Shingrix, the research team was able to compare the side effects of different vaccines.
Data from electronic health records
Given previous indications of protective effects of shingles vaccines against dementia, the team led by Paul Harrison took a closer look at the effects of the new Shingrix vaccine. The scientists analyzed the data from the electronic health records of over 200,000 people aged 65 and over who were vaccinated against shingles.
For this purpose, two groups were formed from the data of the electronic health records, which were as similar as possible in their properties. The first group consisted of around 104,000 seniors who had previously been vaccinated with the conventional vaccine Zostavax against shingles. In the second group, with the same number of seniors, all were vaccinated with Shingrix. The period of observation lasted six years after the last dose of vaccine.
In evaluating the data, the researchers found that those who were vaccinated with Shingrix received a dementia diagnosis 17% later than those who were vaccinated with Zostavax. This means that those vaccinated with Shingrix lived, on average, 164 days longer without a dementia diagnosis.
In a further investigation, the researchers compared the results of the two shingles vaccines with various vaccines against influenza, diphtheria, tetanus, and whooping cough. Here too, Shingrix showed the best results with a delay in dementia of 14 to 27%. "The results are fascinating and encouraging. Given the large and growing number of people affected, anything that could reduce the risk of dementia is welcome," Harrison is quoted as saying in a statement from the university.
Cause of protective effect still unclear
The researchers cannot yet say how the protective effect comes about. "One possibility is that an infection with the herpes zoster virus could increase the risk of dementia. Through inhibition of the virus, the vaccine could reduce this risk. Alternatively, the vaccine also contains chemicals that may have separate positive effects on brain health," says John Todd, who was also involved in the study.
Before proposing the use of the shingles vaccine as a dementia delay, further investigations are needed. However, people should protect themselves against infection with the varicella-zoster virus, which can cause painful shingles and, in some cases, painful nerve inflammation, with a vaccination. In Germany, a vaccination recommendation with two doses is given for everyone aged 60 and over, and for everyone aged 50 and over with an underlying condition such as diabetes or rheumatoid arthritis, or a weakened immune system. In special cases, adults aged 18 and over can also be vaccinated.
The findings suggest that the new Shingrix vaccine, which has shown promising results in preventing shingles, might also delay the onset of dementia. As mentioned by Harrison, individuals vaccinated with Shingrix received a dementia diagnosis 17% later than those who received the conventional vaccine Zostavax, indicating a potential longevity benefit of around 164 days without a dementia diagnosis.
