Article Guardian: Could Alzheimer’s be caused by an infection?

[Sly Saint]

Davangere Devanand, a neurologist at Columbia University Medical Center, combed through the reams of scientific data on Alzheimer’s, he stumbled across a surprising idea – could an infection be involved in driving the disease?

“I was looking for an Alzheimer’s treatment approach that had a reasonable shot of working,” he says. “I found this old theory, going back 35 years, which linked herpes viruses to the disease, and there were all these indirect lines of evidence.”

The further Devanand looked, the more he found. Since the mid-80s, a handful of scientists around the world had doggedly pursued the idea that either a virus or a bacterium could play a role in Alzheimer’s, despite almost complete antipathy from those studying more accepted theories about the disease. Colleagues snubbed them, leading scientific journals and conferences rejected their work and funding had been threadbare, but slowly and surely, they built an increasingly compelling case.

In particular, evidence pointed towards herpes simplex virus 1 (HSV-1) – a pathogen found in 70% of the UK population, and the cause of oral herpes – as a prominent suspect. Studies in the UK, France and Scandinavia suggested that people who had been infected with herpes were more likely to get Alzheimer’s. When Prof Ruth Itzhaki from Oxford University’s Institute of Population Ageing – who has done more than any other scientist to advance the HSV-1 theory of Alzheimer’s – examined postmortem brain samples from patients, she found greater amounts of the virus’s DNA than in people who had not died of the disease.

The main idea for why viruses like HSV-1 and possibly bacteria may be capable of triggering Alzheimer’s is that they invade the body before burrowing into the central nervous system, and travelling to the brain sometime in midlife. Once there, they stay dormant for many years before being reactivated in old age, either because the ageing immune system can no longer keep them in check, or something else – a traumatic episode, a head injury or perhaps another infection – spurs them to life. Once awakened – so the theory goes – they begin to wreak havoc.

For a long time, neurologists treated these ideas as fanciful, until more and more irrefutable evidence arose for the role of pathogens in chronic illness.

Could Alzheimer’s be caused by an infection? | Alzheimer's | The Guardian

 

[Shadrach Loom]

Betteridge can rest easy, I suspect.

 

[Peter T]

Even if everyone with Alzheimer’s is demonstrated to have previously been exposed to HSV-1, given it is such a common virus, as suggested with MS and EBV, though it may turn out to be an invariable or even necessary precursor it is unlikely to be alone a sufficient cause/trigger for Alzheimer’s.

 

[shak8]

Looked up valcyclovir for suppression of oral herpes outbreaks. For most people, that means you take just one pill and that one pill only at the earliest sign of an outbreak.

 

[TigerLilea]

Even if everyone with Alzheimer’s is demonstrated to have previously been exposed to HSV-1, given it is such a common virus, as suggested with MS and EBV, though it may turn out to be an invariable or even necessary precursor it is unlikely to be alone a sufficient cause/trigger for Alzheimer’s.

Isn't EBV the HSV-4 virus? not HSV-1?

 

[Peter T]

Isn't EBV the HSV-4 virus? not HSV-1?

I raised EBV because of the parallel finding that everyone with MS may prove to have had prior exposure/infection to/with that virus, the implication being that EBV is somehow involved in the development of MS. We have a thread here discussing an American study on this. But given how common that virus is I suspect drawing any causal relationship will have to come up with more complex answers.

Similarly if HSV-1 has some role in the subsequent development of Alzheimer’s it is not likely to be simple given how common the virus is, or we would expect a much higher incidence of Alzheimer’s in the general population.