One in three people will develop shingles in their lifetime and the condition is most common in people aged 60 and older.

Shingles, which can lead to a painful rash and, in extreme cases, blindness or hearing loss, is a viral infection that comes from the same virus behind chickenpox.

Some researchers are linking shingles infections to an increased risk of dementia, though they haven’t proven yet that it can lead to dementia.

Is there a connection?

A study by Harvard-affiliated Brigham and Women’s Hospital, which was published in Alzheimer’s Research & Therapy, looked at data from three large studies of men and women. It involved 149,327 participants who filled in health surveys every two years. Both shingles and dementia were on the surveys.

Researchers found that participants with a history of shingles were 20% more likely to experience a condition called subjective cognitive decline.

Scientists aren’t sure exactly why the link seems to exist, but it seems to be stronger among men who carry the APOE4 gene which has been linked to a higher risk of dementia.

The researchers also think shingles could lead to “neuroinflammation, cerebral vasculopathy, direct neuronal damage, and the activation of other herpesviruses like HSV-1,” which may increase the risk of dementia.

“We’re evaluating to see if we can identify risk factors that could be modified to help reduce people’s risk of developing shingles,” the paper’s senior author Sharon Curhan told The Harvard Gazette.

“We also want to study whether the shingles vaccine can help reduce the risk of adverse health outcomes from shingles, such as cardiovascular disease and cognitive decline.”

Vaccinate against shingles for free

Fortunately, you can protect yourself against shingles.

There is a free shingles vaccination in Australia for people aged 65 and older, Aboriginal and Torres Strait Islander people aged 50 and older and high-risk immunocompromised adults with certain medical conditions.

Vaccination is a safe and effective way to protect yourself from serious complications caused by shingles.