Cold sore virus 'could lead to Alzheimer's disease'

A panel of dementia experts has called for further investigation into a potential link between Alzheimer's disease and viruses such as herpes and the chlamydia bacteria.

In an editorial for the Journal of Alzheimer's Disease, 31 leading scientists and doctors accused the scientific establishment of overlooking evidence that dementia is linked to microbes in the brain.

Microbes from the herpes virus, which causes cold sores, and chlamydia bacteria are found at higher rates in the brains of Alzheimer's sufferers, they claim.

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Citing past cases where viral and bacterial microbes have caused dementia-like symptoms, the editorial argues that pathogens from infectious diseases could lie dormant in the brain for years before triggering the onset of Alzheimer's.

"These agents can undergo reactivation in the brain during ageing, as the immune system declines, and during different types of stress," the panel wrote.

Focusing more attention on the possibility of microbes as the answer to the Alzheimer's riddle could open up new treatments and bring science closer to a cure, they argue.

"There is incontrovertible evidence that Alzheimer's disease has a dormant microbial component," Professor Douglas Kell, one of the co-signatories, told the Daily Telegraph. "We can't keep ignoring all of the evidence."

The controversial editorial contradicts the mainstream view that dementia is linked to the build-up of proteins in the brain preventing neurons from communicating.

Professor John Hardy, an expert in neurological disease at University College London, stressed there is currently no convincing proof that infections cause Alzheimer's disease and told The Times the editorial "does not reflect what most researchers think".

Dr James Pickett, the head of research at the Alzheimer's Society, acknowledged that "there do appear to be more [microbes] in the brains of people who have died with Alzheimer's disease". However, he cautioned against making an explicit link without further research and assured the Telegraph that there is "no convincing evidence" that Alzheimer's disease is contagious.