Some common germs could plant the seed for dementia later in life. Research today has found a link between several infectious diseases, in particular herpes Simplex-1 (HSV-1), and a greater risk of Alzheimer’s disease.
Scientists from Gilead Sciences conducted the study, published Tuesday in BMJ Open. They analyzed the medical records of Americans with health insurance, noting that people with Alzheimer’s and related conditions were also more likely to be diagnosed with HSV-1. The results are the latest to suggest that prevention and treatment of HSV-1 and similar viruses can be an effective measure against dementia.
Alzheimer’s disease is the most common form of dementia, affecting around 7 million Americans today. Most cases are caused by a complex mixture of environmental and / or genetic factors. In recent years, many studies have suggested that some infections – HSV -1 include – can be part of this equation. The HSV-1 is the main cause of oral herpes, commonly known as cold buttons, although most infected people feel little or no symptoms; It can also cause genital herpes (mainly caused by HSV-2).
However, not all studies have supported this viral link, so the authors decided to take a look by themselves, using real data. According to the principal researcher Luke Liu, this is the first study to use a large insurance complaint database in the United States to examine the link between Alzheimer’s disease and HSV-1.
Liu and his team compared the health results of nearly 400,000 Americans diagnosed with Alzheimer’s disease in people without Alzheimer who had age, sex and other factors. Only a small percentage of people with Alzheimer’s diagnosis had a past HSV-1 diagnosis (just under 0.5%), but they always had it more often than witnesses (about 80% more probably).
The researchers then examined a wider group of people with other forms of dementia linked to Alzheimer’s disease, finding a similar model. They also found a link between Alzheimer’s disease and two other herpesvirus, herpes Simplex-2 and the chickenpox virus, the cause of chickenpox and shingles. Interestingly, they also found that people who had followed antiviral treatment for their HSV-1 were less likely to develop Alzheimer’s disease than people with HSV-1 who have not received treatment (antivirals can remove and shorten active epidemics, but not cure infection).
Observation studies like this cannot prove a cause and effect link between the HSV-1 and the Alzheimer, but the case of such a connection seems to be stronger.
“Exposure to herpesviruses is likely to be associated with Alzheimer’s disease and other dementia, and anti-Hepetic drugs can be protective against Alzheimer’s disease and related dementia,” said Liu, virologist at Gilead, Gizmodo in an email.
There are important questions about this association, including the real mechanisms involved. Certain research has suggested that the immune system of our brain produces a beta and a tau amyloids to defend itself against herpesvirus infection, for example (the poorly folded forms of these proteins are the main engines of Alzheimer). But there could be more ways including HSV-1 and similar viruses can trigger or speed up the condition.
Other factors almost certainly play a role, especially since many people contract the HSV-1 during their lifetime but never develop Alzheimer’s. According to the World Population Organization under 50. Researchers note that the HSV-1 / Alzheimer’s link is even stronger in the elderly, and other research suggests that people carrying the APOE-ε4 allele-a genetic variant that already increases the risk of Alzheimer-also seems more sensitive to HSV-1 infection. These viruses are therefore probably one of the many dominoes that can fall and ultimately lead to Alzheimer’s disease.
However, global evidence indicates that people can significantly reduce their risk of dementia by treating or preventing certain infections. Several studies have found a link between vaccination of zones in zones and the reduction of Alzheimer’s, for example. Clinical trials testing if antiviral herpes treatments can reduce the risk of dementia may be justified, although Liu notes that the type of research will take considerable resources to start. Research is also underway to develop vaccines for HSV-1 and HSV-2-a research that could be more interesting than the supposed today.
“These results emphasize the prevention of herpesvirus as a public health priority,” wrote researchers.
