Cold sores linked to Alzheimer’s

The findings from researchers at the University of Rochester Medical Centre in the US show that the particular form of the gene that puts people at risk of Alzheimer's also creates a fertile environment for herpes in the brain, allowing the virus to be more active.

This study adds to growing scientific evidence that the herpes virus may contribute in some way to the onset of Alzheimer's.Scientists have known for many years that the ApoE-4 gene is a cause of Alzheimer's disease, but the idea that it works in conjunction with the herpes virus is new.

Other research carried out at the University of Manchester has also proved a link between the herpes virus and Alzheimer's. Specific studies have shown that Alzheimer's patients who have the ApoE-4 form of the gene have more herpes DNA in the brain regions that are affected by Alzheimer's. Other studies at Manchester University have also shown that people with the ApoE-4 version of the gene who are infected with herpes are more likely to get Alzheimer's disease than people infected with herpes who have a different form of ApoE gene, or than people who have the ApoE-4 gene but who don't have herpes.

Scientist are yet to establish a cause for the link between the two conditions although one possibility is that the body's immune response against herpes somehow damages the brain due to inflammation in the brain caused by the immune system fighting the herpes infection.