Published on
Updated
Reading 3 mins.
According to a recent American study, the viral track already mentioned in the appearance of Alzheimer’s disease or other degenerative diseases would have more and more weight. Without being able to affirm a precise causality, 22 different viruses would now be associated with this type of disease.
Research continues to explore the causes of Alzheimer’s disease. On this subject, a new study stands out: it explores the links between viral exposure during life and the appearance of neurodegenerative diseases at a more or less advanced age. Thanks to meticulous work carried out using data from two biobanks, the researchers have updated 22 viruses that could be involved.
A comprehensive approach, different from previous ones
The viral factor in neurological diseases has been emerging for some years. A study published in 2022, for example, showed a strong association between a 32-fold increased risk of multiple sclerosis and previous infection with the Epstein-Barr virus.
“After reading this study, we realized that for years scientists had been searching — one by one — for links between an individual neurodegenerative disorder and a specific virus. That’s when we decided to try a different, more data science-based approach. Using medical records, we were able to systematically search for all possible links at once” explained Michael Nalls, neurogeneticist at the National Institute on Aging in the USA.
The researchers then used the resources of a Finnish project (based on data from 300,000 people) and the UK Biobank (including 500,000 records) to explore potential associations between viral exposures and a variety of common neurodegenerative diseases. The onset of Alzheimer’s disease, amyotrophic lateral sclerosis, dementia, Parkinson’s disease and multiple sclerosis were studied. The team also studied exposure to viral encephalitis, warts, influenza and viral pneumonia.
What associations were found?
The first analysis found 45 significant associations between viral exposure and neurodegenerative disease, reduced to 22 after further analysis. This allowed, according to the study, to update several possible links, without however explaining at this stage the causality that may exist:
- The strongest risk association is between viral encephalitis and Alzheimer’s disease. People who have been exposed to this virus are at least 20 times more likely to be diagnosed with the disease than those who have not;
- Influenza with pneumonia is significantly associated with all diagnoses of neurodegenerative disorders except multiple sclerosis;
- Some of these viral exposures are associated with an increased risk of neurodegenerative disease up to 15 years after infection, and no virus has shown protection against any of these diseases.
Vaccination, a weapon against Alzheimer’s?
The authors point out, however: if all the viruses studied cannot be prevented, some, such as influenza, chickenpox and pneumonia do have a vaccine.
“Although vaccines do not prevent all cases of disease, they are known to significantly reduce hospitalization rates. These data suggest that vaccination may mitigate some risk of developing a neurodegenerative disease.” they conclude.
This study echoes other work that Doctissimo echoed in June 2022, American scientists had found that the flu vaccine was likely to reduce the risk of developing the disease by 40%. Alzheimers. Explanations.
“Several vaccines can protect against Alzheimer’s disease, so we believe that this is not a specific effect of the flu vaccine. Rather, we believe that the immune system is complex and that certain alterations, such as than pneumonia, can activate it in a way that aggravates Alzheimer’s disease”, said at the time the author of the study, Paul. E. Schulz.