Key Takeaways:
- People diagnosed with HSV-1 infection had a higher risk of a subsequent Alzheimer’s diagnosis.
- Antiherpetic drugs reduced Alzheimer’s risk in those diagnosed with HSV-1.
- The findings apply only to people with clinical episodes of cold sores.
MedPage Today – People diagnosed with herpes simplex virus type 1 (HSV-1), the virus responsible for cold sores, were more likely to have a subsequent Alzheimer’s disease diagnosis, an analysis of U.S. commercial insurance claims suggested.
Across 344,628 Alzheimer’s case-control pairs, a history of HSV-1 diagnosis was present in 1,507 people (0.44%) with Alzheimer’s disease and 823 matched controls (0.24%), reported Yunhao Liu, PhD, of Gilead Sciences, a pharmaceutical company based in Foster City, California, and colleagues.
This translated to an adjusted odds ratio of 1.80 (95% CI 1.65-1.96), Liu and co-authors wrote in BMJ Open.
Of patients diagnosed with HSV-1, those who used antiherpetic drugs were less likely to develop Alzheimer’s compared with those who didn’t use antiherpetics (adjusted HR 0.83, 95% CI 0.74-0.92).
“These findings place an even greater emphasis on viewing the prevention of herpesviruses as a public health priority,” Liu and colleagues said.
The results confirm previous findings that people with a history of cold sores may have a higher risk of developing Alzheimer’s disease, and that this risk may be reduced in people who receive antiviral treatment, noted Alberto Ascherio, MD, DrPH, of the Harvard T.H. Chan School of Public Health in Boston, who wasn’t involved with the research.
“This is an observational study based on electronic data of varying quality, so the conclusions cannot be considered definitive,” he wrote in a post on the Spanish Science Media Center website …
Judy George covers neurology and neuroscience news for MedPage Today, writing about brain aging, Alzheimer’s, dementia, MS, rare diseases, epilepsy, autism, headache, stroke, Parkinson’s, ALS, concussion, CTE, sleep, pain, and more. Follow
Disclosures
- This work was funded by Gilead Sciences.
- Liu and most co-authors were employed by and held shares in Gilead. One co-author reported relationships with other pharmaceutical companies.
Primary Source: BMJ Open
Source Reference: Liu Y, et al “Association between herpes simplex virus type 1 and the risk of Alzheimer’s disease: a retrospective case–control study” BMJ Open 2025; DOI: 10.1136/bmjopen-2024-093946
What is herpes simplex virus?
CLEVELAND CLINIC – Herpes simplex virus (HSV) can infect many different parts of your body, most commonly your mouth area (oral herpes) and genitals (genital herpes). HSV causes fluid-filled blisters that break open and crust over wherever the infection is. This is known as a herpes outbreak.
But it’s also possible to have no symptoms and not realize you’re infected.
HSV is highly contagious. It spreads from person to person through skin-to-skin contact. A herpes simplex infection occurs when the virus enters your body through your skin and mucous membranes (mucosa). The virus uses your cells to make copies of itself (replication).
Once you’re infected, the virus stays in your body for life. It’s usually asleep (dormant) but may “wake up” (reactivate) and cause outbreaks. How HSV affects you depends on many factors, including the specific virus type and your overall health.
There’s no cure for HSV. But treatments can help make outbreaks more manageable while lowering the chances that you’ll spread the virus to others.
Types of herpes simplex virus
There are two types of herpes simplex virus:
- Herpes simplex virus type 1 (HSV-1).
- Herpes simplex virus type 2 (HSV-2).
Both HSV-1 and HSV-2 can cause oral herpes or genital herpes. They also cause infections in other areas of your body.
What parts of the body does HSV affect?
Herpes simplex virus can cause infections in your:
- Mouth and face. An oral herpes infection causes cold sores on your lips and around your mouth. Some people develop herpetic gingivostomatitis (sores inside their mouths and other symptoms) when they first get infected. Rarely, sores develop on or inside your nose (nasal herpes).
- Genitals. A genital herpes infection causes sores in your genital area, including the parts you can see (like your vulva or penis) and those you can’t see (like your cervix).
- Skin on other areas of your body. HSV can infect your fingers (herpetic whitlow) or skin anywhere on your body (herpes gladiatorum). Eczema herpeticum, a widespread skin infection, is a complication of HSV infection that affects people with atopic dermatitis.
- Eyes. HSV can cause a serious eye infection called herpes keratitis (a type of ocular herpes).
- Brain and spinal cord. HSV can infect your brain (herpes simplex encephalitis) or the protective layers surrounding your brain and spinal cord (herpes meningitis). If HSV infects both your brain and its protective layers, you can develop a life-threatening condition called herpes meningoencephalitis.
- Other organs. HSV can affect one or more organs in your chest and belly, including your esophagus (herpes esophagitis), lungs (HSV pneumonia) and liver (HSV hepatitis). These types of infections are more likely to affect people who are immunocompromised.
