A new study suggests that the virus responsible for cold sores, called herpes simplex virus type 1 or HSV-1, might be linked to Alzheimer's disease.
Researchers published their findings in BMJ Open after reviewing data from a large U.S. health insurance database. They studied over 340,000 people aged 50 and above who were diagnosed with Alzheimer's between 2006 and 2021. Each person with Alzheimer's was compared to someone of similar age, gender, and location who didn't have the disease to reduce bias in the study.
They checked how many people had been diagnosed with HSV-1 and whether they had taken antiviral medicine for it. They found that 0.44 percent of people with Alzheimer's had a previous HSV-1 infection, compared to 0.24 percent of those without the disease. This means having HSV-1 was linked to an 80 percent higher chance of developing Alzheimer's, although the overall number of cases was still small.
Interestingly, those who received antiviral treatment for HSV-1 had about a 17 percent lower risk of getting Alzheimer's than those who didn't get treatment.
However, the study had some limitations as participants were older adults on Medicare, which means that they weren't well represented in the data. Also, past HSV-1 infections may have been missed if it occurred before the person's medical records were included in the database. There may also have been confusion between HSV-1 and another form of the virus, HSV-2.
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December 12, 2025 15:14 ET Central bank decisions dominated the economic news flow this week led by the Federal Reserve. Trade data from the U.S. also gained attention. The Canadian and Swiss central banks also announced their interest rate decisions. Inflation data from China was in focus as the country released the latest consumer price and producer price data.