Retraction Watch

Tracking retractions as a window into the scientific process

Dental X-rays linked to Alzheimer’s disease? Abstract saying so temporarily withdrawn

with 22 comments

Alzheimer’s & Dementia has “temporarily withdrawn” a 2012 abstract, slated for publication next month, linking Alzheimer’s disease with exposure to dental x-rays.

The author is Caroline Rodgers, a self-described “independent writer/researcher who investigates public health issues and advocates for change.” Although we can’t find the text, we’re guessing that its premise is similar to that of her 2011 paper in Medical Hypotheses, titled “Dental X-ray exposure and Alzheimer’s disease: a hypothetical etiological association.”

Here’s the abstract from that paper:

Despite the fact that Alzheimer’s disease was identified more than 100 years ago, its cause remains elusive. Although the chance of developing Alzheimer’s disease increases with age, it is not a natural consequence of aging. This article proposes that dental X-rays can damage microglia telomeres – the structures at the end of chromosomes that determine how many times cells divide before they die – causing them to age prematurely. Degenerated microglia lose their neuroprotective properties, resulting in the formation of neurofibrillary tau tangles and consequently, the neuronal death that causes Alzheimer’s dementia. The hypothesis that Alzheimer’s is caused specifically by microglia telomere damage would explain the delay of one decade or longer between the presence of Alzheimer’s brain pathology and symptoms; telomere damage would not cause any change in microglial function, it would just reset the countdown clock so that senescence and apoptosis occurred earlier than they would have without the environmental insult. Once microglia telomere damage causes premature aging and death, the adjacent neurons are deprived of the physical support, maintenance and nourishment they require to survive. This sequence of events would explain why therapies and vaccines that eliminate amyloid plaques have been unsuccessful in stopping dementia. Regardless of whether clearing plaques is beneficial or harmful – which remains a subject of debate – it does not address the failing microglia population. If microglia telomere damage is causing Alzheimer’s disease, self-donated bone marrow or dental pulp stem cell transplants could give rise to new microglia populations that would maintain neuronal health while the original resident microglia population died.

Rodgers, who goes by the blog handle “Science Siren,”  submitted public testimony in support of her theory at a meeting last month of the U.S. Department of Health and Human Services’ Advisory Council on Alzheimer’s Research. Her take-home message:

It is not realistic to believe that decades of dental X-ray exposure would be without consequence for all people. The question is not, “Why should we consider whether dental X-rays are causing Alzheimer’s,” but rather, “Why didn’t we think of this sooner?”

Rodgers told us that she presented the poster last July at a meeting in Paris of the Alzheimer’s Association.

The abstract was not included in the Journal’s special supplement of conference abstracts, which is why it is being published in the main journal in March.

And she said the withdrawal was not a retraction — the published abstract will be forthcoming. An official at Elsevier, which publishes Alzheimer’s & Dementia, informed her that the abstract

was withdrawn as an “article in press” because it was an abstract for a poster session, not a full article. He said, “We specifically did not use the word ‘retracted’ because we did not want to indicate there was anything wrong with it.”  The abstract will be published in the March issue, as planned.

We confirmed that with Elsevier, and learned that the problem arose from a misclassification of the abstract in the editorial office of the journal.

Rodgers hasn’t limited her research to the causes of Alzheimer’s disease. Another area of interest for her is an alleged link between autism and exposure to prenatal ultrasound:

If prenatal ultrasound is the primary reason siblings of children with autism are at higher risk for being diagnosed with ASD, it would explain why previous sibling studies did not show as high a sibling risk: as ultrasound’s potential acoustic output, applications and occasions have increased, so has the risk.

And we might expect even more theories from her. After all, as she notes on her blog:

I have developed original ideas regarding the part that heat plays in everything from the onset of labor to the location of body hair to the roller coaster of circadian rhythms we experience every day.

Most exciting is how these conjectures, if proven true, can have a beneficial impact on public health.

Written by amarcus41

February 22nd, 2012 at 11:58 am

  • Pymoladdict February 22, 2012 at 1:01 pm

    I see no reason for the Medical Hypothesis to be treated as a scientific publication. As a corollary – I have no respect for journals that publish abstracts of conferences, or pseudo-papers which are essentially expanded abstracts, since both types of publications further erode already compromised state of scientific literature, by avoiding even the pretense of peer-review.

    • ccrodgers February 22, 2012 at 2:45 pm

      In response to Pymoladdict’s spirited comment: 1) The correct title is not “Medical Hypothesis” but “Journal of Medical Hypotheses” (please note the plural form); 2) the Journal of Medical Hypotheses is peer reviewed; 3) the publication that issued the temporary withdrawal of my abstract was the Journal of Alzheimer’s and Dementia.

      Further, publishing abstracts provides an efficient means of sharing a number of different ideas. Are all of them accurate? Of course not — scientific understanding is constantly evolving. Scientists are always building on the accurate or flawed body of published work. As for “the pretense of peer-review,” can Pymoladdict suggest something better?

      By the way, I think Retraction Watch does a great job reporting on this important aspect of scientific publishing.

      • Neuroskeptic February 22, 2012 at 3:15 pm

        No… the correct title is Medical Hypotheses. Not “Journal of”.

      • Neuroskeptic February 22, 2012 at 3:20 pm

        As for whether Medical Hypotheses is peer reviewed, it is now, but it wasn’t until 2010, under long-time editor Bruce Charlton who argued forcefully that it was a unique journal where radical ideas could be published outside the constraints of peer review.

        Your article on dental X-rays was submitted in Dec 2010 (according to the journal site) so it would have been amongst the very first papers to be peer reviewed.

      • Pymoladdict February 23, 2012 at 4:32 pm

        Thanks to the vigilance of Neurosceptic the name business was sorted out. As did the peer-review question. I can’t tell whether your opus was reviewed, what I can tell is that the style and content of this publication roughly matches the output we get from the mediocre graduate students charged with literature overview. The statement pretense of peer-review in marginal/tangential journals – including Medical Hypotheses, which seems to get itself one – refers to the fact that proliferation of such journals heavily taxes the pool of experts needed for the review process, yet those journals possess nothing to attract such experts. As a result the worst kind of peer-review emerges – expert-free pay-to-publish review process where nonsensical or superfluous manuscripts are “reviewed” (rather flagged through) by various bottom-feeders and accepted by the editors mostly concerned with the publication fees.
        Publishing of abstracts as papers re-inforces pay-to-publish model – plainly advertised by some unscrupulous conferences and journals as such – pay registration and publication fees and beef up your CV and grant proposals with “papers”. No peer review or a perfunctory one.
        Of course Medical Hypotheses is a notorious laughing stock, and a publication therein would not normally confuse a human operator. His or her job of tracking relevant literature and separating papers deserving attention from the deluge of flack becomes more difficult when a paper originates in one of the journals that has Molecular Cell(ular) Biology and combinatorial permutations thereof in the title.
        The damage done by poorly-or-not-at-all-reviewed published non/missense is greatly augmented by recent employment of AI in compiling secondary, tertiary etc. databases. In just one troubling example of over-reliance on scientific standards missing from many “scientific” publications, such respectable and otherwise well-thought-out database as STRING uses the instance of 2 proteins mentioned in the same text as indication of their interaction. Again, a scientist can probably sort it out, not as easily the same can be accomplished by a consumer of medical info, also assembled with use of AI, which gives texts from Nature Medicine the same weight as the Medical Hypotheses.
        So if I was too curt in my response, I apologize. I have my reasons. Frustrations of a scientist are not easily understood by somebody merely wishing to play one in a blog.

  • Samuel Smith February 22, 2012 at 2:18 pm

    I think as scientist we should not doubt odd theories simply because they make us uncomfortable with our own progress and developments. We are exposed to enough garbage from the environment that we introduced to improve our quality of life that it may sum up to have negative in vivo effects. We go with global warming as a a man made issue so why not something more personal.

    • Pymoladdict February 22, 2012 at 2:33 pm

      I don’t see how ideas of a self-styled armchair “researcher” would make me “unconformtable” with my progress in experimental molbiology. What does make me unconfortable is the erosion, subversion, and perversion of what passes for a scientific publication nowdays. Here we have an example of blogging blending in with what some mistake for “research”. The problem is that there is really difference between the drivel that gets published in Medical Hypothesis and musings/ravings of some home-schooled blogger. What next? Pubmed indexation of Facebook pages?

      • Neuroskeptic February 22, 2012 at 3:25 pm

        What you’ve gotta remember is that Medical Hypotheses dates from an era when there were no blogs. You either published your ideas in a journal or you stood on a street corner ranting them. As such I think it may have played a valuable role in the pre-internet era, but it’s unnecessary now we have blogs.

  • Pymoladdict February 22, 2012 at 2:34 pm

    Sorry, “no” got eated (between really and difference).

  • Booker February 22, 2012 at 6:41 pm

    I actually have a lot of time for Medical Hypotheses. The content can vary from genuinely good ideas to ones that seem quite absurd, but I guess “them’s the brakes” when dealing with hypotheses. I think regardless of how you view the journal Medical Hypotheses, we could probably all agree that we definitely need new ideas in order to progress medical research, and the journal is the only one I know of dedicated to publishing hypotheses. It’s worth noting that it’s sister journal that ran for a while – Biomedical hypotheses – stopped due to apparent lack of submissions.

    Some would say if you have a hypothesis you should follow it up with data, but I think that view is entirely unrealistic. They say a good researcher has more ideas than they can follow up on, and sometimes you have an idea while bogged down and committed to ongoing studies, with no real possibility of attracting funding and doing the work on them yourself, so publishing a hypothesis without data becomes the only option.

    So the question really is what is the best avenue for publishing hypotheses. As noted above, maybe now in the time of blogs and more online activity there are other ways of getting ideas out there, but in all honesty I do truly worry that in this day and age of ‘publish or perish’ that the focus has turned too far towards generating and publishing data, as opposed to advancing understanding and coming up with ideas and hypotheses which link those various bits of data together. (Although obviously, without data there would be no understanding…). Maybe a topic a bit too complicated to thrash out in a blog comments sections! But regardless, I think we need more ideas, not less. Some of those will be worthwhile, and inevitably some not so ….

    • puzzled monkey (Conrad T Seitz MD) February 22, 2012 at 7:22 pm

      @Booker: agree and disagree. The focus has to be on generating (and, we hope, publishing) data because that is where the thankless, boring work is. Generating hypotheses is fun. Finding a hypotheses that can be confirmed with data depends on experience and talent. Actually generating the data, in an objective way, is a lot of work. For which you ought to get paid. Thus, “publish or perish.”
      I’m impressed with your opinion of Medical Hypotheses. I thought it was a rag printed on used Kleenex, but that’s probably because I’ve only seen the truly ridiculous abstracts in it that attract notice elsewhere. I will check it out.
      As to the subject at hand: if there were a statistical association between dental Xrays and Alzheimer’s Disease (and I’m not saying there is or not), what would the etiologic mechanism be, assuming that there was a casual relationship? Nevermind the stuff about telomeres. When they Xray my teeth they usually miss my brain. So is it the mercury in the fillings? (Just kidding.)
      I think that, before you try to publish a hypothesis, you should be thoroughly familiar with the subject matter at hand. Putting together Xrays and a disease(any disease) requires more than guilt by association. Also, it helps at grant writing time to posit a reasonable etiologic mechanism for your hypothetical causative association (using lots of big words doesn’t hurt.)

      • Brett February 23, 2012 at 9:57 am

        I can think of a pretty obvious non-causal origin for a correlation between dental x-rays and Alzheimer’s: People who take good care of their health are more likely to get regular dental check-ups. They are also more likely to live longer and thus are more likely to die of Alzheimer’s.

      • puzzled monkey (Conrad T Seitz MD) February 23, 2012 at 12:05 pm

        There you go. Interference by another variable that is etiologically related to the independent variable must be “filtered out” statistically. Probably eliminating any statistical significance to the original correlation. More time wasted on a hypothesis that wasn’t reasonable to start with because their wasn’t any logical relationship between the two variables in question: the frequency of dental Xrays and the incidence of Alzheimer’s Disease.
        That’s why one needs a thorough understanding of the subject before making hypotheses, or I should say, before trying to do experiments to test your hypotheses.
        BTW: Medical Hypotheses is Extremely Interesting.

  • ccrodgers February 23, 2012 at 12:17 pm

    Although Einstein believed that imagination was more important than knowledge, there are clearly limits to mere airmchair speculation. The articles I have read in Medical Hypotheses are well supported by dozens of citations. My article on dental X-rays and Alzheimer’s has 94 citations. Anyone truly interested in refuting a hypothesis might want to consider reading the material that supports it before dismissing it on the basis of a few lines read on a blog. That said, all comments — informed or otherwise — are welcomed.

    • puzzled monkey (Conrad T Seitz MD) February 23, 2012 at 2:30 pm

      Yeh. I was able to access your list of references in the Med Hypoth article, although I couldn’t get to the full article for less than $31.50…sorry I don’t have that much on me at the moment.

      The list of references is interesting. There does seem to be a weak relationship in the incidence of meningiomas to certain high dose dental Xrays, but no dose-response relationship.
      There is also a dramatic increase in the incidence of adult intracranial malignancies secondary to childhood head irradiation for tinea capitis in Israel between 1948-60. Fascinating and tragic.
      There is also a paradoxical study showing a decreased incidence of gliomas from amalgam fillings and dental Xrays…that’s a small case-control study, easy to discount.

      None of those references appears to promise to provide any reasonable foundation for your hypothesis; they are all tangential.
      The fact that a majority of people who live long enough (over 85) develop Alzheimer’s-like dementia is very important. The etiology of Alzheimer’s Disease is far more likely to lie in the biochemistry of neurofibrillary tangles: how the tangles are laid down, and so on, based on an inborn error in metabolism. The incidence of early Alzheimer’s-like dementia in Down’s Syndrome practically screams a genetic etiology. The fact that certain antidepressant drugs relieve the pathology in rodents is also very instructive.

      I did, however, find your poster presentation. It consists of a series of coincidences easily explained by confounding factors, such as life expectancy, changes in diagnostic emphasis, etc. There is not one logical connecting link. I rate this junk science, and I don’t think anyone with a skeptical mind takes it seriously.
      If I were NIH, I would reject funding for a research study to confirm this hypothesis. Thank Heaven I’m not.

      Keep in mind that the number of references you have doesn’t have a positive relationship to the value of your publication. The gyre paper by Andrulis had 800 references, and it is no good. Its one defender here, nettle, was reduced to citing testimonials by people who had read the paper and emailed their support. It reminds me of those chiropractors who give testimonials from their patients in their advertisements.

    • Pymoladdict February 23, 2012 at 6:22 pm

      There you go – “my article”… Do you want a list of logical fallacies that populate your “article”? Well, it would be quite a long one. I actually read as much of it as one can take, and can confirm that this “article” HAS 94 references, which doesn’t mean it IS SUPPORTED by 94 references. There is your argumentum verbosum and onus probandi rolled into one. Quoting Einstein is beyond cute. It is more sad than amusing that a dude made famous by his contribution to theoretical physics is most often quoted by people who routinely flunk calculus and pchem 101… Providing reassuring soundbites for rejects and crackpots, and graphic fodder for T-shirts – could Einstein himself imagine that this would be his most practicable legacy?..

  • ccrodgers February 24, 2012 at 10:00 am

    As reluctant as I am to dignify the kind of bile spewed by Pymoladdict with a response, I feel compelled to point out that a hypothesis is an idea that has not yet been tested — otherwise, it would simply be a statement of fact. Insulting new ideas is like shooting fish in a barrel — it’s easy but it can really stink.

    • puzzled monkey (Conrad T Seitz MD) February 24, 2012 at 12:06 pm

      Good line, but dead fish already stink. I never was a good fisherman, so I couldn’t catch a dead fish. (by the way, did you know that actual experiments show that you can kill fish in a barrel by shooting into it without actually hitting the fish?)
      I like “argumentum verbosum” and “onus probandi” better to summarize my concerns about this publication (notice I’m avoiding the pejorative use of quotes around “paper” or “article” so I’m better at restraining myself than pymoladdict, who is a self-admitted addict, heheheh). These terms succinctly characterize the errors that pervade it. Even a hypothesis has to have some logical, data-related foundation to make any contribution to the literature.
      Einstein has been spinning in his grave in response to your tortured use of his statements.

  • puzzled monkey (Conrad T Seitz MD) February 24, 2012 at 1:14 pm

    This irrelevant, but worth sharing: “argumentum verbosum” is actually “argumentum verbosium” which Wikipedia describes, amusingly, as:
    “Proof by intimidation (or argumentum verbosium) is a jocular phrase used mainly in mathematics to refer to a style of presenting a purported mathematical proof by giving an argument loaded with jargon and appeal to obscure results, so that the audience is simply obliged to accept it, lest they have to admit their ignorance and lack of understanding.[1]”
    “onus probandi” is “burden of proof” which is much more complex.

  • Bryan Maloney February 25, 2012 at 2:30 pm

    The general public does not understand what a hypothesis is. A large subset probably REFUSES to understand what a hypothesis it. Instead, they blindly believe whatever agrees with their prejudices. Thus, if some self-styled “journal” publishes a “hypothesis” to the order of “Prenatal ultrasound may be linked to autism”, then the general public will stupidly leap upon that publication as “scientific proof” that ULTRASOUNDS CAUSE AUTISM, OMGOMGOMGOMGOMGOMG!!!!!!!!!

    Now, if the hypothesis proposer is responsible, they’ll fight against this and agree with the scientists who say that the hypothesis is untested and should not be taken as fact. However, if the proposer is a scoundrel, they will simply find an appropriate cult to defend them, such as the discredited researcher who faked a “link” between autism and vaccines.

  • chris February 25, 2012 at 3:57 pm

    Bryan, it doesn’t necessarily matter if the hypothesis proposer is responsible or not, although it does help if they are! Unfortunately the (print) media tend to publicise wacko hypotheses since that’s what sells papers. So (in the UK) the Daily Mail (and even the Telegraph) are happy to publish complete rubbish on science related to climate change (oddly, the Wall Street Journal is the major US science misrepresenter); the UK Times completely misrepresented the science on AIDS by choosing to promote the falsehood that HIV isn’t the cause of AIDS; the Daily Mail continuted to promote scaremongering and anti-science interpretations on MMR/autism long after aceptable skepticism in MMR was justified….and so on.

    Sadly, there are huge vested interests in promoting false interpretations of scientific matters. Scientists do need to be responsible in publicising their hypotheses. But often things are taken out of their hands, and rubbish is promoted anyway.

    It’s true ‘though that increasingly the aim of the “scoundrel” is to get rubbish in support of self-serving interests published in the scientific literature, so that the “appropriate cult” has something apparently “respectable” to defend! Again, climate science provides good examples of this (i.e. self-serving rubbish “sneaked” into the scientific literature), ‘though the Andrew Wakefield MMR/autusim is an example from medical sciences.

  • Harbo February 25, 2012 at 10:48 pm

    Correlation/causation, Data mining, etc and scientific openness, do not mean we have to dwell in the “postmodern” myth that all ideas are equally valid.
    This is a shot from the hip, as is the autism from ultrasound.
    There MAY be correlation but it is no stronger than…people with Alzheimer’s used to daydream, thus daydreaming causes Alzheimer’s so ….lets wait for useful data and well designed studies and try to discourage the media from the sound-byte reporting of medicine.
    Medical Hypotheses was a great way to stimulate new and lateral thought , but now as a source of lazy copy it may be cumulatively harmful.

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