Herpes Simplex Virus-1 and Alzheimers

Yeah… so remember that herpes vaccine?

We just got another reason to want that bad boy (as if we needed another reason):
Herpes simplex virus type 1 DNA is located within Alzheimer’s disease amyloid plaques.

So Wozniak et al cut up the brains of 11 people (who had kindly asked that their bodies be donated to science after their deaths)– 6 who had Alzheimers, 5 who did not. Turns out that ~90% of the plaques in the brains of Alzheimers patients also contained HSV-1 DNA and 72% of the HSV-1 DNA they found in the brain was in these plaques. There is a connection here. It might be that HSV-1 gets into your brain and causes problems (ie Alzheimers) as your immune system declines when you get old.

Well shit. Depending on the age group you look at, 50-95% of us are infected with HSV-1. Everybodys got it.


No, no ‘shit’. No reason to freak out over this. Please keep in mind this lab only looked at the brains of 6 Alzheimers patients, and the 5 ‘normal’ people. The ‘normal’ people were all HSV-1 positive too– they ALL had HSV-1 in their brains as well. But no Alzheimers.

So for the love of gawd, if you get cold sores, or you know youre HSV-1 positive, DO NOT FREAK OUT thinking you are destined to lose your mind. For Petes sake, this fact has NOT been emphasized in the billion pop-science articles I have read on these findings. DO NOT FREAK OUT.

This really is kinda good news. We have drugs for herpes that work really well. Aciclovir, and its relatives (Valtrex and such). Low toxicity, can get in the brain okay, so, um, yay!

If HSV-1 ultimately ends up being the cause of Alzheimers, we can deal with that! Better than tearing our hair out trying to figure out how to tame stem cells and gene therapy vectors and how to deliver siRNA and other crazy stuff weve been trying! Or hell, even the not-so-crazy stuff– handfuls of drugs that (evidently) dont work!

I repeat, HSV-1 people, DO NOT SPAZ! There is still a ton of research to do. This paper doesnt mean you will get Alzheimers. This paper might mean we are really close to a solution to Alzheimers.



  1. #1 biopunk
    December 9, 2008

    Abbie, you ROCK!!!

    Thanks for blogging!

  2. #2 kevin
    December 9, 2008

    Educate me: correlation/causation?

    You’re like oh, HSV-1 must be eating your brain and pooping plaque.

    But I’m like, well maybe HSV-1 eats this plaque for breakfast, just not quick enough to keep you from getting Alzheimers?

  3. #3 PalMD
    December 9, 2008

    It’s an interesting start, but as abbie, whom i worship, pointed out, with the prevalence of HSV1 being so high, it’s going to be hard to dig out causation without a lot more data.

  4. #4 Clark Goble
    December 9, 2008

    I’d think the first study I’d want to see is some study about how many people with herpes end up with Alzheimers. Of course that’d take some time. In the meantime trying to find out how many current Alzheimers have herpes somewhere versus a wider sample would be interesting. It may just be that Alzheimers (or whatever causes it) make one prone to get the virus (or spread it within your body).

  5. #5 MattK
    December 9, 2008

    So, I read the abstract, but that’s it since I don’t have a subscription. Also, I’m not a physiologist or virologist (as you can probably guess from my lack of subscription if not from all any misinterpretations that I might provide). However, just reading the abstract it seems that there are 3 lines of evidence here: 1) correlation between Alzheimer’s and HSV-1 (in people with the type 4 allele of the apolipoprotein E gene); 2) experimental induction of beta amyloid (plaque gunk) in mouse brains and cell lines by HSV-1 infection; and 3) strong association between HSV-1 DNA in effected tissues (reported in this study). At least one of the lines of evidence is experimental rather than just correlational. It seems that the authors conclude that HSV-1 infection plays a causal role (and may be a necessary cause??) but it is not, on it’s own, a sufficient cause.

  6. #6 msta
    December 10, 2008

    Given the percentage of people who have herpes and the fact that you can’t get rid of it, what about how many people who end up with Alzheimers who never had herpes? Also, what about all those other forms of herpes; chicken pox, shingles, etc? Has anyone looked into other possible variants (not-quite-Alzheimers-diseases)? Just curious; no herpes here.

  7. #7 Christophe Thill
    December 10, 2008

    I don’t know a lot about neurobiology, and I may be about to say something stupid. But does this really demonstrate a link between the virus and Alzheimer’s disease? I mean, perhaps the amyloid plaques are just an environment that the virus loves? Perhaps more Alzheimer brains should be cut up (I know, they don’t grow on trees…), in order to see whether the virus is really always present in the plaques? 6 cases is not a lot…

  8. #8 Paul
    December 10, 2008

    MattK, you’re right. Their in vitro and mouse work was published in Neuroscience Letters in 2007 (doi:10.1016/j.neulet.2007.09.077). They also found that levels of the enzymes responsible for beta-amyloid production also increased following HSV1 infection.

    What excites me about this work is that it is as far as I’m aware the first time that a plausible trigger for the chain of events leading to the development of amyloid plaques has been identified. Interestingly they also mention an earlier study by another group which found amyloid plaques in the brains of mice infected with Chlamydia pneumoniae, so it’s possible that HSV1 is not the only infectious agent that can trigger the onset of Alzheimers.

    What I’m wondering is how early will treatment to eradicate HSV1 infection need to be started to prevent or stop the development of Alzheimers. I suspect that other treatments that remove plaques and tangles will still be required in many cases.

  9. #9 chris y
    December 10, 2008


    As someone with cerebral palsey, can I go through motions of objecting to this expression? I’ve long ago given up expecting to influence anybody, but it gives me something to do.

  10. #10 manigen
    December 10, 2008

    @chris y: is spaz a reference to spasticity then? I had assumed it was an abreviation of spasm.

    Apparently I was being naive…

  11. #11 chris y
    December 10, 2008

    manigen, the word “spastic” is derived from “spasm”, and was originally applied medically as a straightforward description of the symptoms of cerebral palsy. “Spaz” is a common abbreviation, used interchangeably with the full word as an insult to mean weak or uncontrolled. The verb derived from the noun.

    Like I say, disabled people aren’t a sexy minority, and I long ago gave up expecting “progressive” people to extend me the same linguistic courtesy they give to women, LGBT people and racial minorities. Nowadays I just mention it once in a while for shits and giggles.

  12. #12 Ian
    December 10, 2008

    “I repeat, HSV-1 people, DO NOT SPAZ! There is still a ton of research to do”

    So you’re saying that there’s no simplex answer to this problem?!

  13. #13 rrt
    December 10, 2008

    Yeah, ok, but…I’m still freaking out a little.

  14. #14 William Wallace
    December 10, 2008

    How do you get HSV-1, again?

  15. #15 rrt
    December 10, 2008

    Dang, hit post too soon. A question I meant to ask:

    I get moderately frequent cold sore outbreaks. Years ago I had a scrip for Zovirax, which didn’t seem to help much (though it was hard to take with the proper regimen). Eventually I gave up on it. About a year ago I went back to a doc to see what other options were available, and he gave me Valtrex (not regular use, just for when it flares up…thank Dog given the insane price!). I think it may work better, but here’s the thing that prompts my question: Since I started taking this, it seems like the lip sores have migrated to my mouth (base of the tongue canker sores). I’ve never had this pattern of expression before. Could the drug cause this? How?

  16. #16 rrt
    December 10, 2008

    Don’t even go there, WW. You’ll lose.

  17. #17 W. Kevin Vicklund
    December 10, 2008

    How do you get HSV-1, again?

    Kissing. Obviously, you’re not at risk.

  18. #18 synapse
    December 10, 2008

    “How do you get HSV-1, again?”

    Kissing, sometimes from family members during childhood. I got my first cold sore out of the blue at like age 8.

  19. #19 embertine
    December 11, 2008

    Thanks, Abbie, for speaking some sense about this. This reminds me of the crap that came out when aluminium was found in the plaques too. What, you mean the most common metal on the planet, that’s basically in everything you eat, was found in your brain tissue? GET OUT!

    rrt, I can only speak from my experience and those of friends. When I first got infected, my outbreaks were frequent and painful. Ten years later, I almost never get cold sores.

    I have had friends, however, who started only with sores on the lips, and then after a few years got them inside the mouth and even in the nose (ouchie!). We all used the same medication (Zovirax), so I can only suggest that our immune systems dealt with the virus with different degrees of effectiveness? Hope yours settle down soon.

  20. #20 Jon H
    December 11, 2008

    Yeah, it’s Herpes B you need to worry about.

  21. #21 daedalus2u
    December 23, 2008

    There are a few problems with this hypothesis. Amyloid builds up in many tissues, not just the brain. Normally amyloid doesnít accumulate because the removal pathways remove it faster than it can build up. Those removal pathways include the proteasome (for small pieces of junk) and autophagy for large pieces. Autophagy also happens to be the way that DNA from dead cells gets removed. If you inhibit autophagy, you cause the accumulation of protein aggregates including amyloid.

    Brains with fewer plaques have the same (or higher) HSV-1 DNA content but have a smaller fraction of the total brain HSV-1. That would make sense if all they are seeing is that the amyloid plaques have more partially degraded DNA because what ever is inhibiting the degradation of amyloid (and so is allowing it to accumulate) is also inhibiting the degradation of DNA from dead cells.

    I bet that if you looked for other DNA, such as from endogenous retroviruses, you would find more of it in those plaques too.

    I bet you would find more junk of all sorts. Everything that doesnít get cleared by autophagy will accumulate to higher levels. I bet you would be able to find any virus that persists, including chicken pox.

    Paul, there was a study that removed amyloid plaque via vaccination. The technique worked in that it removed plaque, but it had no effect on the progression of dementia. The “problem” of Alzheimer’s is upstream of the formation of plaque. Plaque is an effect, not a cause.

  22. #22 eddie
    February 22, 2009

    I just read of a spanish company that are claiming to have a vaccine for alzheimers, made from chicken polyclonal antibodies. Claim trials in dogs show effectiveness.

    It seems to me they think alz is caused by one or more viruses, as discussed here, and are using a scattergun approach. A more modern wart-puss treatment?

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