The virus that causes cold sores may be linked to risk of Alzheimer’s disease, according to Swedish researchers.
Several studies in recent years have indicated a possible connection between infection with the common herpes virus, herpes simplex virus type 1, and Alzheimer’s disease.
Once a person is infected, the virus stays in the body and reactivates from time to time. It is possible that the natural weakening of the immune system among older adults creates chances for the virus to spread to the brain, say researchers at Umea University, Sweden.
They investigated whether this could trigger the process that leads to Alzheimer’s disease.
The team, led by Dr Hugo Lovheim carried out two large studies. The first involved 3,432 adults followed for an average of 11 years. It found that a reactivated herpes infection doubled the risk of Alzheimer’s disease.
The second study looked at brain samples donated from 360 people with Alzheimer’s disease, taken about ten years before diagnosis. This also showed an approximately double risk of Alzheimer’s disease if the person carried the herpes virus.
Both studies appear in the journal Alzheimer’s & Dementia.
Dr Lovheim says: "Our results clearly show that there is a link between infections of herpes simplex virus and the risk of developing Alzheimer’s disease. This also means that we have new opportunities to develop treatment forms to stop the disease."
He added: "Something which makes this hypothesis very interesting is that now herpes infection can in principle be treated with antiviral agents. Therefore within a few years we hope to be able to start studies in which we will also try treating patients to prevent the development of Alzheimer’s disease."
Lovheim, H. et al. Herpes simplex infection and the risk of Alzheimer’s disease – A nested case-control study. Alzheimer’s & Dementia 7 October 2014 doi: 10.1016/j.jalz.2014.07.157
Lovheim, H. et al. Reactivated herpes simplex infection increases the risk of Alzheimer’s disease. Alzheimer’s & Dementia 17 July 2014 doi: 10.1016/j.jalz.2014.04.522
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