Herpes infection may double dementia risk in older adults, study finds

Research is latest to indicate some viral infections may play a yet-unidentified role in furthering cognitive decline

Older adults exposed to the herpes virus behind the common cold sore may see a doubling of their dementia risk, a new study warns.

The research, published in the Journal of Alzheimer’s Disease, is the latest to indicate that some types of viral infection play a yet-unidentified role in furthering cognitive decline.

Herpes simplex virus type 1, or HSV-1, is a common infection behind oral sores and carried by nearly 3.7 billion people across the world under the age of 50, while dementia affects nearly 55 million people.

HSV-1 infection is lifelong, but symptoms may come and go over different periods and many people may never exhibit any signs they were infected at any point in their lives.

The new study confirms that herpes simplex virus could also be a possible risk factor for dementia.

In the study, researchers studied 1,000 70-year-olds from Uppsala over 15 years.

It found that people who had been infected with HSV-1 at some point in their lives were twice as likely to develop dementia, compared to those who had never been infected.

Researchers found that the association held regardless of the two strongest predicting factors of Alzheimer’s disease today: age and people carrying a variant of the gene APOE-4.

“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,” study co-author Erika Vestin, a medical student at Uppsala University, explained.

The findings support previous research hinting at a link between HSV infection and Alzheimer’s disease.

“More and more evidence is emerging from studies that, like our findings, point to the herpes simplex virus as a risk factor for dementia,” Ms Vestin said.

Researchers hope to conduct further studies to assess whether already known drugs against the herpes simplex virus can reduce the risk of dementia.

They hope the results may drive dementia research further toward treating the illness at an early stage using common anti-herpes virus drugs.