Infectious hypothesis of Alzheimer disease

Herpes simplex virus 1 (HSV-1) is the most commonly studied pathogen in the context of AD, primarily due to identification years ago of HSV-1 DNA in AD patient brains at autopsy [9,10]. De Chiara and colleagues demonstrated that recurrent reactivation of HSV-1 in a wild-type mouse model could produce hallmark AD pathology, accompanied by cognitive deficits, an intriguing result that supports the hypothesis that reactivation is critical in the connection between herpesviruses and AD. Use of any antiherpetics resulted in hazard ratios well below 1.0, indicating decreasing risk of developing dementia. First and foremost, important questions on the relationship between established risk factors of AD and pathogen infections remain to be addressed.