Un vaccin contre le zona pourrait retarder la démence.
La démence est une maladie liée à l'âge crainte qui devrait toucher plus de personnes à l'avenir. Les chercheurs ont maintenant des indices selon lesquels un vaccin contre l'herpès zoster relativement nouveau, en plus de prévenir l'herpès zoster, pourrait également arrêter la démence.
L'utilisation du vaccin contre l'herpès zoster Shingrix a entraîné une diminution des cas de démence chez les personnes âgées de 65 ans et plus aux États-Unis, selon des chercheurs de l'Université d'Oxford. L'effet était observable chez les femmes et les hommes, mais plus marqué chez les femmes, selon les résultats publiés dans la revue "Nature Medicine".
L'introduction du nouveau vaccin Shingrix, utilisé aux États-Unis depuis 2017, a fourni un point de départ idéal pour la recherche. Auparavant, il n'était possible de comparer les effets secondaires des vaccins contre l'herpès zoster que chez les personnes vaccinées et celles non vaccinées. Comme il est connu que les personnes qui se font vacciner ont tendance à mener une vie plus saine dans l'ensemble, ces résultats de recherche étaient sujets à des erreurs et donc seulement partiellement significatifs. Cependant, avec l'approbation du nouveau Shingrix, l'équipe de recherche a pu comparer les effets secondaires de différents vaccins.
Données des dossiers médicaux électroniques
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 de l'effet protecteur encore inconnue
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.
