Alzheimer's could be caused by viruses like herpes
Alzheimer's disease could be caused by viruses like herpes, a group of renowned dementia experts have warned, as they call for urgent investigation into the link.
The worldwide team of 31 scientists and clinicians, which includes specialists from Oxford, Cambridge, Edinburgh and Manchester Universities and Imperial College, London, suggest microbes are the major cause of dementia.
The herpes virus - the type which causes cold sores - and chlamydia bacteria are named as the major culprits, as well as a type of corkscrew-shaped bacteria called spirochaete.
Currently, most scientists are trying to find treatments which prevent the build-up of sticky amyloid plaques and misfolded tau proteins in the brain which prevent neurons from communicating with each other, leading to memory loss and cognitive decline.
But in the editorial in 'The Journal of Alzheimer's Disease', it is suggested that it is viral or bacterial infections that trigger the plaque build-up in the first place. Targeting them specifically with antimicrobial drugs could halt dementia.
Professor Douglas Kell of the University of Manchester's School of Chemistry, said: "We are saying there is incontrovertible evidence that Alzheimer's Disease has a dormant microbial component. We can't keep ignoring all of the evidence."
The authors say that viruses and bacteria are common in the brains of elderly people, and although they are usually dormant, they can "wake up" after stress or if the immune system is compromised.
About two-thirds of people will acquire the herpes virus at some point in their lives, and many will not realise they have it. The herpes virus is known to damage the central nervous system, and the limbic system in the brain which regulates mood and instinct and is associated with mental decline.
They also point to the fact that a gene mutation - APOE e4 - which makes one in five people more susceptible to Alzheimer's disease, also raises their susceptibility to infectious disease.
Viral infections in the brain are known to cause symptoms similar to Alzheimer's and the experts say the link has been "neglected" for too long. (© Daily Telegraph, London)