The herpes virus is a common infection, but it can have serious consequences with age. (Photo: Colourbox)

Cold sores linked to dementia

Herpes infections can double the risk of developing Alzheimer’s disease.

Although Alzheimer’s is a major health challenge, little is known about the causes of the disease.

For years, scientists have suspected that the herpes virus does more harm than just causing sore lips: It may be one of the causes of Alzheimer’s. More and more research has pointed towards a connection.

As much as 90 percent of the population is infected with herpes virus type 1, herpes simplex. In most cases, the virus remains dormant, but sometimes it leads to small cold sores around the mouth.

The virus has been found in 90 percent of all plaque, the characteristic protein deposits that are found in the brains of patients with Alzheimer’s.

Alzheimer’s disease is one of the most common causes of dementia. (Photo: Colourbox)

Two new studies done at Umeå University in Sweden have found a clear link.

“Our results clearly show an association between infections with herpes simplex and the risk of developing Alzheimer’s disease,” states researcher Hugo Løvheim.

Spreads to the brain

Herpes simplex type 1 does not disappear after infection; rather, it is stored in the tissues of the infected person, especially in nerve cells. From time to time the infection flares up.

Scientists have suspected that the weakened immune systems of elderly people can allow the virus to spread to the brain, leading to the development of Alzheimer’s. This theory has now been confirmed, according to two new studies.

In the first study, 3432 individuals were followed for 11 years. A reactivated herpes infection doubled the risk of developing Alzheimer’s.

In the other study, samples from 720 individuals were investigated, half of them patients with Alzheimer’s. The samples were taken over a 10-year period. Again, carriers of the herpes virus had twice the risk of developing Alzheimer’s.

New treatments

Currently there is no treatment for Alzheimer’s, and the changes it causes in the brain inexorably lead to severe dementia. The symptoms can be postponed by medication, but they can’t be reversed or halted.

The results of the new studies allow researchers to look for new treatments.

“If we can identify patients with Alzheimer’s caused by herpes, treatment with antiviral drugs should affect the disease,” says Løvheim.

Read the Norwegian version of this article at

Translated by: Lars Nygaard

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