The Strange Link Between Cold Sores and Alzheimer’s Disease

A new study links HSV-1 infection with nearly a doubling of Alzheimer’s disease risk.

Two-thirds of you watching this will know the feeling. It starts with sort of a numb, tingly, feeling in the lip. A day or so later, some redness, some swelling and then, yup, a cold sore. It’s a little frustrating, maybe a little embarrassing, but you wait it out for a few days and it goes away. No big deal, right?

Except for the fact that multiple studies suggest that cold sores might increase your risk for Alzheimer’s disease.

Cold sores come from a viral infection, specifically herpes simplex virus 1 (HSV-1). There are multiple herpesviruses, which are all DNA viruses and include HSV-2 which causes the sexually transmitted infection, though to be fair both HSV-1 and 2 can lead to both types of infections. Varicella — the virus that causes chicken pox and shingles, Ebstein-Barr virus, CMV — all herpesviruses. If you’re human, you have almost certainly been infected by at least one. In any case, HSV-1 is one of the most common viral infections in the world. It’s estimated that about two-thirds of the adult population are infected.