Herpes and the Brain: Could a Common STI Be Fueling the Dementia Crisis?

A recent study has found that men infected with genital herpes (HSV-2), a sexually transmitted infection, are more than twice as likely to develop dementia compared to uninfected men. HSV-2, which can remain dormant and asymptomatic for life, is a silent but infectious STI. This suggests that a history of infection could be an early warning sign for increased dementia risk.

HSV-2 is transmitted through genital contact, oral, or anal sex. Symptoms can include burning sensations, pain, blisters, ulcers, and painful urination in the genital area. The virus can lie dormant in nerve ganglia before reactivating. Approximately 80% of those infected show no symptoms, often unaware of their infection. This lack of awareness can lead to increased long-term neurological risks if left undetected.

In South Korea, about 30-40% of the population over 40 years tests positive for HSV-2 antibodies. Asymptomatic infections are common even among younger individuals, leading to unknowing transmission. Despite this prevalence, actual diagnoses in medical facilities are rare. Many people don’t seek medical attention during early infection, missing crucial opportunities for treatment and prevention.

On Thursday, researchers from the University of Texas Institute for Neurodegenerative Diseases revealed their findings. They analyzed the electronic health records of 33.23 million Americans aged 65 and older, examining the link between herpes virus (HSV) infections and dementia onset.

The study compared 19,554 individuals with HSV infections to a control group of 96,569 without infections. The HSV group was further categorized into those with oral herpes (HSV-1), HSV-2, and dual infections to assess dementia risk.

Men with HSV-2 infections showed a 2.06 times higher risk of developing dementia compared to those without any HSV history. The risk was 1.76 times higher for the HSV-2 group, 1.66 times for the HSV-1 group, and 2.44 times for those with both types.

While there was no significant gender difference in dementia risk for HSV-1 or HSV-2 infections, men with HSV-2 were found to be nearly twice as likely as women to develop dementia.

The researchers suggested that these findings point to potential biological pathways influenced by HSV-2 that differ between sexes. They speculated that variations in hormones or immune responses might play a role in regulating disease progression or severity.

The team explained that HSV infections can trigger inflammatory responses in the brain, damaging nerve cells and potentially leading to dementia. They stressed the need for long-term studies to clarify the relationship between specific pathogen infections and neurodegeneration. Such research could be crucial in developing strategies to prevent and treat dementia, particularly in understanding how viral infections like HSV impact dementia risk and progression.

This groundbreaking study was published in the February issue of the Journal of Alzheimer’s Disease under the title Increased Risk of Dementia Associated with Herpes Simplex Virus Infections.