The herpes virus behind cold sores is a major cause of the protein plaques that accumulate in the brains of people with Alzheimer’s, mounting evidence are showing.
A team of scientists from the University of Manchester found DNA evidence of the herpes simplex virus (HSV) type 1 in 90% of plaques in Alzheimer’s disease patients’ brains. They had previously shown that HSV1 infection of nerve-type cells in mice leads to deposition of the main component of the plaques – beta amyloid. And that the virus is present in the brains of many elderly people and that in those people with a specific genetic factor, there is a high risk of developing Alzheimer’s disease.
Taken together, the researchers say the findings strongly implicate the cold sore-causing virus as a root cause of Alzheimer’s dementia. They 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.
In turn, this causes damages the brain cells, which die and then disintegrate, releasing the proteins which develop into amyloid plaques.
The findings are published in the Journal of Pathology.
Source: BBC News, 8 December 2008
Chapter: Alzheimer's Disease :: 7 January 2009
