Exposure to a virus linked to the common cold sore could double someone’s risk of developing dementia, a new study has warned.
Research, by a team at Uppsala University in Sweden, found that people who have had the herpes virus at some point in their lives could be twice as vulnerable to the condition, compared to those who have never been infected.
They hope this could pave the way for research into the potential of using anti-herpes drugs as a way to lower dementia risk.
Herpes simplex virus, or HSV, is a common infection that can cause painful blisters or ulcers.
It spreads via skin-to-skin contact and is carried by around 3.7 billion people under the age of 50 across the world
There are two types of HSV, HSV-1 and HSV-2. HSV-1 is far more common and causes infections in or around the mouth but can also spread to the genitals.
HSV-2 spreads by sexual contact and causes genital herpes.
A herpes infection is lifelong, but symptoms may come and go over time and many people may never display symptoms to indicate they were infected at any point in their lives.
The new research, published in the Journal of Alzheimer’s Disease, is the latest to indicate that some types of viral infection can be linked to furthering cognitive decline.
As part of the study, a group of 1,000 70-year-olds from Uppsala were followed over a period of 15 years.
It found that people who had been infected with HSV at some point in their lives were twice as likely to develop dementia, compared to those who had never been infected.
This was found to be the case regardless of the two strongest predicting factors of Alzheimer’s disease today: age and people carrying a variant of the gene APOE-4.
Study co-author Erika Vestin, a medical student at Uppsala University, explained: “What’s special about this particular study is that the participants are roughly the same age, which makes the results even more reliable since age differences, which are otherwise linked to the development of dementia, cannot confuse the results.”
55 million people worldwide are affected by dementia. Advanced age and carrying the APOE-4 risk gene are already known risk factors.
The findings come as previous research has already hinted at a link between HSV infection and Alzheimer’s disease.
“It is exciting that the results confirm previous studies,” Erika said.
“More and more evidence is emerging from studies that, like our findings, point to the herpes simplex virus as a risk factor for dementia.”
The team said there is now a need to further investigate whether already known drugs against the herpes simplex virus can reduce the risk of dementia and the possibility of developing new vaccines.
Erika added: “The results may drive dementia research further towards treating the illness at an early stage using common anti-herpes virus drugs, or preventing the disease before it occurs.”
According to the World Health Organisation, common oral herpes symptoms include blisters (cold sores) or open sores (ulcers) in or around the mouth or lips.
Common genital herpes symptoms include bumps, blisters, or open sores (ulcers) around the genitals or anus.
These sores and blisters are typically painful. Blisters may break open, ooze and then crust over.
During their first infection people might experience:
- Fever
- Body aches
- Sore throat (oral herpes)
- Headache
- Swollen lymph nodes near the infection.