Updated Mon. Dec. 8 2008; ~ CTV.ca News Staff

Those who get frequent cold sores may be at higher risk for developing Alzheimer's disease, a new study suggests.

The study, conducted by researchers from the University of Manchester, suggests that the herpes simplex virus, which causes cold sores, is also a major cause of the plaque found in the brains of Alzheimer's patients.

The researchers discovered that 90 per cent of plaques found in the brains of Alzheimer's patients contain DNA from the herpes simplex virus type 1 (HSV1). Therefore, it appears that HSV1 is a major contributor to the development of plaques in the brain.

The findings, published in the Journal of Pathology, suggest that vaccination against the virus may help prevent the onset of Alzheimer's one day.

"Antiviral agents would inhibit the harmful consequences of HSV1 action; in other words, inhibit a likely major cause of the disease irrespective of the actual damaging processes involved," researcher Matthew Wozniak said in a statement. "Whereas current treatments at best merely inhibit some of the symptoms of the disease."

Alzheimer's is a neurological disease that is characterized by progressive memory loss and cognitive impairment.

While researchers know that Alzheimer's patients share the same brain abnormalities - namely plaque deposits and tissue tangles that damage healthy, living brain cells - the exact cause of the disease is unknown.

There is no cure for Alzheimer's, which affects about 20 million people worldwide, numbers that are expected to grow rapidly as the boomer population ages.

These latest findings add to the team's previous work, which found HSV1 in the brains of elderly people, many of whom had a higher risk for developing Alzheimer's disease if they also carried a specific genetic mutation.

"We suggest that HSV1 enters the brain in the elderly as their immune systems decline and then establishes a dormant infection from which it is repeatedly activated by events such as stress, immunosuppression, and various infections," researcher Prof. Ruth Itzhaki said in a statement.

"The ensuing active HSV1 infection causes severe damage in brain cells, most of which die and then disintegrate."

The researchers will next study if antiviral agents have an impact on how HSV1 affects the brain, as well as the effect they may have on improving symptoms in Alzheimer's patients.