They’re uncomfortable, embarrassing, and difficult to get rid of, but cold sores can also be a warning sign of dementia.
Scientists from Sweden published a paper linking the virus behind cold sores, herpes simplex virus-1 (HSV-1), to an increased risk of the memory-robbing disease.
By studying more than 1,000 elderly people for 15 years, researchers found that people infected with HSV-1 were twice as likely to develop dementia than those who were not infected.
Scientists aren’t sure why the two conditions are linked, but it could be that the disease hides in your nervous system for life.
Flare-ups can happen at any time, which can cause inflammation in the nervous system, compressing and damaging the delicate tissue of the nervous system and brain.
The theory goes that over time this could lead to some of the changes associated with dementia, such as memory loss, brain tissue breakdown and confusion.
This is just the latest in a series of articles exploring a link between common viruses and the risk of dementia later in life.
Recently, scientists have also linked the varicella-zoster virus, which is behind chickenpox and shingles, to changes in brain health.
Cold sores are caused by the Herpes simplex virus 1. Another strain of the same virus causes the STD that leads to genital herpes
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Still, experts say the evidence is mixed and other studies have found no link between the virus and cognitive decline.
According to Johns Hopkins, HSV-1 affects between 50 and 80 percent of American adults. This virus is similar to, but not the same as, the virus that causes the STD herpes.
It’s even reportedly teasing celebrities like comedian Jim Carrey and singer Usher.
The virus is mainly spread through intimate personal contact, such as kissing or oral sex, although in some rare cases it can be spread through sharing drinks.
It can also be passed from mother to child in the womb and cause serious side effects in children.
Once someone contracts the disease, many of the symptoms are manageable and mild. The first signs include fever, swollen lymph nodes, sore throat, and ulcers in the mouth and gums.
After the initial flare-up, symptoms may disappear completely before periodically popping up on the side of the mouth or lip as a red, ulcerated ulcer.
During one of these flare-ups, doctors may prescribe antiviral medications or ointment to ease discomfort, or instruct patients to take over-the-counter pain relievers such as ibuprofen to control inflammation.
For a long time, doctors thought this unsightly visitor was one of the only lingering effects of the disease.
In recent years, however, a more worrying connection has emerged.
This also applies to the team of researchers from Uppsala University, who published their findings in December 2023 in the Journal of Alzheimer’s Disease.
Their study followed 1,002 Swedes, 80 percent of whom are carriers of HSV-1, over 70 years old, for a period of 15 years.
They adjusted for factors such as educational status and genetic predisposition to Alzheimer’s disease.
At the end of the study, 32 subjects had developed Alzheimer’s disease and 63 percent had developed another form of dementia. In total, this represented 11 percent of participants. Eighty-nine percent of those people had herpes.
Researchers then compared these people to the rest of the group, who had not developed dementia by the end of the study, with 82 percent of participants having herpes.
After adjusting for TK, they found that those who had contracted herpes were two times more likely to develop some form of neurodegeneration.
They note that their limitations include not being able to adjust for the influence that age may have on the data, and also not being able to rule out other factors such as medications, heart disease and diabetes.
In the US, an estimated 4 percent of adults over the age of 65 have dementia. For comparison: experts from Johns Hopkins estimates that between 50 and 80 percent of the population has HSV-1.
As many as 80 percent of Americans may have some form of the herpes virus. Usher’s diagnosis became public in 2019 after a lawsuit. Jim Carrey’s diagnosis became public amid an ex-girlfriend’s 2017 lawsuit alleging the actor failed to inform her of his condition
Their article is not the first to link the two.
A 2024 study Researchers in South Korea using data from a national health insurance agency including more than 750,000 people found that people with HSV and varicella zoster virus (VSV) were more likely to develop dementia.
However, not all studies of these two factors have found a link. A review from 2019 from multiple universities in Great Britain found that the link between dementia and HSV-1 was inconclusive and did not establish a strong association.
Dr. Jagan PillaI, a cognitive neurologist at the Cleveland Clinic, told Parade that the studies are not conclusive enough to conclude that herpes could cause dementia. Of the 2019 study from Britain, he said, “it supports the need for better quality future studies.”
In addition, Dr. Monica Gandhi, an infectious disease specialist at UC San Francisco, said Medical news today the rate of herpes infections is generally much higher than the rate of dementia.
This difference, she said, is evidence that they may not be connected.
She said: ‘Given how common herpes virus infection is in young people, I wouldn’t worry too much about this study.’