TREATING cold sores with anti-viral medicines could slash the risk of Alzheimer’s disease by 17 per cent, research suggests.
Previous studies have found that the herpes simplex virus – which causes cold sores – can lie dormant in human cells for a lifetime before “re-awakening”, leading to dementia symptoms.
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Experts have discovered that herpes simplex virus type 1 (HSV-1) causes changes similar to those observed in the brains of dementia patients, such as amyloid plaque-like formations and inflammation.
Now, a large US study suggests that treating HSV-1 may be a route to lowering the risk of Alzheimer’s disease.
Researchers from the pharmaceutical firm Gilead Sciences and the University of Washington in Seattle used data on 344,628 people with Alzheimer’s aged over 50 who had been diagnosed with the disease between 2001 and 2006.
Nearly two thirds (65 per cent) of those with Alzheimer’s disease were women, with an average age of 73.
They matched participants’ information to data from the same number of people without Alzheimer’s.
Of the Alzheimer’s patients, 1,507 (0.44 per cent ) had been diagnosed with HSV-1.
Just 823 of the other group (0.24 per cent) had been infected by the virus.
The study found that people who’d been infected with herpes had an 80 per cent increased risk of Alzheimer’s, even when other factors were taken into account.
But those with HSV-1 who used anti-virals to treat the virus were 17 per cent less likely to develop Alzheimer’s compared with those who did not take the medicines.
Among the 2,330 people with a history of HSV-1 infection, 931 (40 per cent) used anti-virals after their diagnosis.
Dr David Vickers, from the University of Calgary in Canada – who wasn’t involved in the research – said the “research exaggerates the role of HSV-1, failing to appreciate its absence in 99.56 per cent of Alzheimer’s disease cases”.
He added: “The observed 17 per cent [risk] reduction with anti-herpetic drugs translates to a mere nine-month delay in Alzheimer’s disease onset.”
The authors, writing in the journal BMJ Open, concluded: “Findings from this large study implicate HSV-1 in the development of Alzheimer’s disease and highlight anti-herpetic therapies as potentially protective for Alzheimer’s and related dementia.”
In the UK, the drug aciclovir is used to treat cold sores, chickenpox, shingles and other herpes virus infections.
The researchers also looked at the potential role of other herpes viruses, including HSV-2 – which can be responsible for genital herpes – the varicella zoster virus that causes chickenpox, and cytomegalovirus.
Both HSV-2 and varicella zoster virus infections were also associated with a heightened risk of Alzheimer’s disease.
Exactly how HSV-1 and other viruses might raise the risk of dementia is not clear, the researchers pointed out.
“However, studies have shown that inflammatory alterations in the brain caused by HSV infection are pivotal in Alzheimer’s disease development,” they noted.
Other ways to reduce your Alzheimer’s risk
Be physically active
Regular physical activity is crucial for overall health and may help reduce the risk of dementia, including Alzheimer’s disease. Aim for at least 150 minutes of moderate-intensity activity per week.
Eat a healthy diet
A balanced diet, potentially including the Mediterranean diet, can help reduce your risk of dementia, as well as other health conditions.
Stay mentally active
Keeping your mind active can strengthen your brain’s ability to cope with disease. Engage in activities like reading, learning new skills, or playing brain games.
Manage other health conditions
Maintaining healthy blood pressure, cholesterol, and blood sugar levels can also contribute to reducing your risk of dementia.
Prioritise sleep
Aim for seven to eight hours of quality sleep each night, as sleep deprivation can negatively impact brain health.
Maintain good heart health
Taking care of your heart health, including avoiding smoking and excessive alcohol consumption, can also lower your risk of dementia and other diseases.
Seek medical advice
If you have any concerns about your health or a family history of Alzheimer’s, consult with a healthcare professional.
HSV-1 DNA is also found in the plaques characteristic of Alzheimer’s disease, and people carrying the most common genetic risk factor for the disease are more susceptible to HSV infections, researchers added.
But scientists who were not involved in the study were quick to point out that herpes infections are extremely common in the general population, and that contracting the virus didn’t guarantee someone would develop Alzheimer’s.
Dr Richard Oakley, director of research and innovation at the Alzheimer’s Society, said: “Results from this observational study suggested that people with recorded cold sore infections were more likely to develop Alzheimer’s disease, and interestingly those prescribed antiviral drugs had a slightly lower risk.
“But this doesn’t prove that cold sores cause Alzheimer’s disease, or that anti-virals prevent it.
“The data came from insurance records, often based on self-reported symptoms which may miss or misclassify infections, and didn’t track how often people had cold sores or how consistently they took medication.
“Much more research is needed to explore exactly how viruses might be involved and before we can draw firm conclusions.”
Professor Tara Spires-Jones, from the University of Edinburgh, said: “This is a well-conducted study adding to strong data in the field linking HSV-1 and other viral infections to increased risk of developing Alzheimer’s disease, but it is important to note that HSV-1 infection, which is extremely common in the population, is by no means a guarantee that someone will develop Alzheimer’s.
“Why viral infections may increase 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 from Alzheimer’s disease as we age, including a better understanding of links between viral infection and Alzheimer’s risk.”
Dr Sheona Scales, director of research at Alzheimer’s Research UK, welcomed the study but said more research was needed.
“We know there are 14 established risk factors for dementia, and there’s not enough evidence to include infections in this list.
“This study doesn’t tell us if infections are causing the risk, it only shows an association. Further research is needed to understand what the underlying biology around this is.”
