Catching the virus that causes cold sores almost doubles the risk of developing Alzheimer’s – but the treatment lowers the opportunities, suggests an investigation.
Researchers discovered earlier that the Herpes Simplex virus type 1 (HSV-1) can be lifelong in human cells in human cells before they ‘look up again’, leading to dementia symptoms.
It has been shown that it causes changes that resemble those in the brain of dementia patients, such as amyloid plaque-like formations and inflammation.
Now a large study suggests that treating HSV-1 can be a way to reduce the risk of Alzheimer’s disease.
Scientists, including the pharmaceutical company Gilead Sciences and the University of Washington in Seattle, used data on 344,628 people with Alzheimer’s linked to the same number of people without the disease.
All were older than 50 and the diagnosis of Alzheimer’s was made between 2006 and 2021.
A history of HSV-1 diagnosis was noticed for 1,507 (0.44 percent) patients with Alzheimer’s, compared to 823 (0.24 percent) of those without.
Almost two -thirds (65 percent) of those with Alzheimer’s disease were women, with an average age than 73.
Catching the virus that causes cold sores almost doubles the risk of developing Alzheimer’s – but the treatment lowers the opportunities
The study showed that people who had suffered the herpes virus had an 80 percent increased risk of Alzheimer’s, even when other factors were taken into account.
But those with HSV-1 who used antivirals to treat the virus were 17 percent less likely to develop Alzheimer’s compared to those who did not do the medication.
Among the 2,330 people with a history of HSV-1 infection, 931 (40 percent) used antivirals after their diagnosis.
The authors, who are open in the magazine BMJ, concluded: “Finding findings of this large … Study implies HSV-1 in the development of Alzheimer’s disease and emphasize anti-herpetic therapies as potentially protective for Alzheimer’s and related dementia.”
In the UK, the Aciclovir drug is one of that available for the treatment of cold sores, chicken pox, shingles and other herpes virus infections.
Data from the open prescription website indicate that doctors spend around 90,000 recipes for the medicine in England every month.
The researchers also looked at the potential role of other herpes viruses, including HSV-2, Varicella zoster virus (which causes chickenpox) and cytomegalovirus.
Both HSV-2 and Varicella Zoster virus infections were also associated with an increased risk of Alzheimer’s disease.
Amyloid plaque formation between neurons in Alzheimer’s disease
Exactly how HSV-1 and other viruses can increase the risk of dementia is not clear, pointing to the researchers.
“Studies have shown that inflammatory changes in the brain caused by HSV infection are crucial in the development of (Alzheimer’s disease),” they added.
HSV-1 DNA is also found in the plaques that are characteristic of Alzheimer’s disease, and people who carry the most common genetic risk factor for the disease are more sensitive to HSV infections, they said.
Professor Tara Spires-Jones, van de Universiteit van Edinburgh, zei: ‘Dit is een goed geconditeerde studie die bijdraagt aan sterke gegevens in het veld dat HSV-1 verbindt en andere virale infecties tot een verhoogd risico op het ontwikkelen van de ziekte van Alzheimer, maar het is belangrijk om op te merken dat HSV-1-infectie, die uiterst vaak voorkomt in de populatie, een garantie is dat iemand Alzheimer zal to develop.
‘Why viral infections can increase the risk of dementia is not fully understood, but the most likely explanation is that infections increase inflammation in the body and contribute to age -related brain inflammation.
“More research is needed to understand the best way to protect our brains against Alzheimer’s disease as we get older, including a better understanding of connections between viral infection and the risk of Alzheimer’s.”
Dr. David Vickers, from the University of Calgary in Canada, said that the research “exaggerates the role of HSV-1, so that its absence in 99.56 percent of the cases of Alzheimer’s disease is not appreciated.”
He added: “The observed 17% hazard reduction with anti-herpetic medicines translates into a delay of only nine months at the start of Alzheimer’s disease.”
Professor Tara Spires-Jones, from the University of Edinburgh
The study showed that people who had suffered the herpes virus had an 80 percent increased risk of Alzheimer’s, even when other factors were taken into account
Dr. Richard Oakley, director of research and innovation at the Alzheimer’s Society, said: ‘The results of this observational study suggested that people with registered cold painful infections previously developed Alzheimer’s disease, and it is interesting that the prescribed antiviral medicines had a slightly lower risk.
‘But this does not prove that cold sores cause Alzheimer’s disease, or that antivirals prevent this.
‘The data came from insurance records, often based on self -reported symptoms that can miss or incorrectly classify infections, and did not keep track of how often people had cold sores or how consistently they took medication.
“Much more research is needed to investigate exactly how viruses can be involved and before we can draw strong conclusions.”
Dr. Sheona Scales, director of research at Alzheimer’s Research UK, welcomed the study, but said that more research was needed.
‘We know that there are 14 established risk factors for dementia, and there is not enough evidence to include infections in this list.
‘This study does not tell us whether infections cause the risk, it only shows an association. Further research is needed to understand what the underlying biology around it is. ‘
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