[HN Gopher] Flu vaccination linked to 40% reduced risk of Alzhei...
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       Flu vaccination linked to 40% reduced risk of Alzheimer's disease
        
       Author : cachecrab
       Score  : 156 points
       Date   : 2022-06-27 19:45 UTC (3 hours ago)
        
 (HTM) web link (www.uth.edu)
 (TXT) w3m dump (www.uth.edu)
        
       | _Microft wrote:
       | Summary: there were hints from smaller studies or studies on
       | particular groups (e.g. veterans) that flu vaccinations can
       | reduce the probability of elderly people to develop Alzheimer's
       | dementia. Here, almost 1 million pairs of recently flu vaccinated
       | and not vaccinated people were matched and studied. A large
       | protective effect was found. Other adulthood vaccinations show
       | similar effects, hinting at a more general mechanism. There is a
       | section about hypothesized mechanisms in the paper [0] which also
       | points towards more general effects and not simply "avoidance of
       | infection".
       | 
       | Search [0] for "Hypothesized mechanism" or even "BCG" for a
       | concrete example of a vaccine that most likely does not act via
       | prevention of infection (it is a tuberculosis vaccine and most
       | people never get tuberculosis. It still shows a protective
       | effect).
       | 
       | [0] https://content.iospress.com/articles/journal-of-
       | alzheimers-... (Open Access)
        
       | caromontminy wrote:
       | Great news ! It's good to know that flu vaccination has two
       | benefits
        
         | geraldwhen wrote:
         | Correlation is not causation. Ice cream sales don't cause
         | drowning.
        
           | JumpCrisscross wrote:
           | > _Correlation is not causation_
           | 
           | No, but correlation isn't meaningless either. This study [1]
           | appears to be as robust as one can get without doing a
           | double-blind trial. Given the effect size, I suspect that is
           | in the works.
           | 
           | [1] https://content.iospress.com/articles/journal-of-
           | alzheimers-...
        
           | dragontamer wrote:
           | Correlation is sufficient to draw additional studies to add
           | to the discussion however.
           | 
           | And with a proper survey, you can actually account for a lot
           | of these effects. (Ex: after accounting for outdoor
           | temperatures, the Ice Cream Sales / Drowning correlation can
           | be largely factored out).
        
           | itsoktocry wrote:
           | > _Ice cream sales don't cause drowning._
           | 
           | Imagine thinking this study and those datasets are remotely
           | the same.
        
       | dangom wrote:
       | That's an incredible effect size.
       | 
       | Mechanisms hypothesized to be at play:
       | 
       | "These mechanisms--and those underlying the effects of adulthood
       | vaccinations on all-cause dementia risk in general--can be
       | grouped into at least three broad, non-exclusive categories: 1)
       | influenza-specific mechanisms, including mitigation of damage
       | secondary to influenza infection and/or epitopic similarity
       | between influenza proteins and AD pathology; 2) non-influenza-
       | specific training of the innate immune system; and 3) non-
       | influenza-specific changes in adaptive immunity via lymphocyte-
       | mediated cross-reactivity."
        
         | fsiefken wrote:
         | Purely anecdotal; I found it odd to see my mother (diagnosed
         | with alzheimer 3/4 year ago) behaving and talking more coherent
         | days after her mRNA covid-19 vaccine shots. I thought perhaps
         | the immune response lessened the symptoms temporarily.
        
         | Fomite wrote:
         | Whether or not that's an incredible effect size sort of
         | depends. For infectious disease epidemiology, which regularly
         | sees _extremely_ strong effects because of the very short
         | causal chain between an infection and an outcome, it 's not all
         | that extraordinary.
        
       | i_love_limes wrote:
       | Epidemiologist in training here... There are quite a few comments
       | in this thread already jumping on the 'correlation != causation'
       | train. While that is true, I'd like to clarify a couple things:
       | 
       | 1. The journal article didn't suggest it was causal. But such a
       | correlation with such a large population warrants publication and
       | further research into causation.
       | 
       | 2. literally the first thing that any epidemiologist would
       | consider is potential confounders. There is a big list of
       | covariates they included into their model here:
       | https://content.iospress.com/articles/journal-of-alzheimers-...
       | 
       | There are quite a few things that can be done to alleviate
       | potential false correlations: DAGs, prior literature, removing
       | confounders, and including covariates are all things at disposal.
       | 
       | 3. Such a large sample size + previously reported findings + an
       | inclusion of enough covariates still doesn't == causation, BUT
       | it's important to publish and shout about so we can then look
       | into the potential biological underpinnings that may cause this.
       | Which by the way, those experiments may still use data science
       | techniques.
       | 
       | 4. If you are actually interested, there is a whole topic of this
       | called 'causal inference' with one famous criteria list called
       | the 'Bradford Hill Criteria':
       | https://en.wikipedia.org/wiki/Bradford_Hill_criteria. This list
       | is often argued about.
       | 
       | 5. If all of this information was new to you, please stop
       | spouting 'correlation != causation'. You probably don't know as
       | much as you think
        
         | aaron695 wrote:
        
         | georgia_peach wrote:
         | Thank you for posting this. I doubt people can make it to
         | adulthood--or even manage speaking in complete sentences--
         | without having some rudimentary appreciation for " _correlation
         | != causation_ ", yet it is so frequently posted--both here &
         | the r-place.
         | 
         | And its vileness is far beyond midwittery. It is a lazy &
         | incredibly weasely way to stifle unwelcome lines of inquiry: by
         | pre-emptively accusing anyone who would continue along those
         | lines as a mental defective.
         | 
         | That being said, modern research is mostly a profit/status
         | driven false-positive factory.
         | 
         | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1182327/
        
         | amacneil wrote:
         | If they only intend to claim correlation, avoiding the word
         | "linked" in the announcement would probably help with general
         | public interpretation.
         | 
         | I feel like in English, "linked" usually implies some sort of
         | potential causation, not just a general relationship. For
         | example: "boyfriend linked to murder case".
        
           | kixiQu wrote:
           | What's wrong with implying _potential_ causation? Correlation
           | _is_ potential causation. The whole reason one says the
           | boyfriend is _linked_ to the murder case is because one _isn
           | 't_ saying he's responsible -- and yet he _might_ be.
        
           | sudosysgen wrote:
           | Correlations do imply a link, though. They don't imply
           | causation, but in the absence of selection bias and with
           | enough of a sample size, it is almost certain there is a link
           | somewhere.
        
             | toolz wrote:
             | Well let's test this theory out then. Would you say I was
             | being ridiculous if I told you that the number of people
             | who drown in a year is linked to how many movies nicolas
             | cage appears in?
             | 
             | If so, then you might not actually believe linked is simply
             | a synonym for correlation. I know I certainly would think
             | that was a ridiculous way to phrase it.
        
               | 2muchcoffeeman wrote:
               | That's just being facetious though. We've all seen that
               | website with funny correlations. This line of argument
               | while an important lesson to look deeper into systems
               | before claiming a correlation doesn't really add much
               | here.
               | 
               | Loads of people get the flu vaccine. Enough that I'd
               | imagine the sample size is representative of the
               | population at large. A large number of people also don't
               | get the flu vaccine. So this is a surprising result.
               | Especially since we are injecting a liquid into the
               | people so there could reasonably be some effect we never
               | thought of. Which is the whole point. These people aren't
               | correlating things in completely unrelated fields and
               | claiming a link.
        
               | MrsPeaches wrote:
               | > the number of people who drown in a year is linked to
               | how many movies nicolas cage appears in
               | 
               | For those who don't know the reference:
               | http://www.tylervigen.com/spurious-correlations
        
             | hypertele-Xii wrote:
             | The word for when there is no link is, in turn,
             | 'coincidence'.
             | 
             | Causation, correlation, coincidence.
             | 
             | And then there's quantum entanglement.
        
           | pcl wrote:
           | This reminds me of the intentionally-ambiguous "officer-
           | involved shooting" turn of phrase.
           | 
           | https://www.mcsweeneys.net/articles/an-interactive-guide-
           | to-...
           | 
           | https://www.cjr.org/analysis/officer-involved-shooting.php
        
         | itsoktocry wrote:
         | > _There are quite a few comments in this thread already
         | jumping on the 'correlation != causation' train._
         | 
         | Complaining about correlation not being causation is the
         | perfect theme for the midwit meme. It's one of my pet peeves.
        
           | mortenjorck wrote:
           | The brainlet and sage text is "maybe x causes y."
        
           | [deleted]
        
           | planarhobbit wrote:
           | I'd say they should show evidence that they know what they're
           | talking about, but then I'd be accused of credentialism.
        
             | LargeWu wrote:
             | Being able to demonstrate technical understanding of a
             | problem isn't credentialism. Conversely, having an
             | undergraduate degree in X isn't evidence of expertise.
        
         | BrandoElFollito wrote:
         | I do not remember where I read it (probably xkcd) but it was
         | that correlation is not casuation, though the numbers are doing
         | big winks to you (or something like that)
         | 
         | As a physicist who had to endure helping biologists with
         | statistics and cooling down their enthusiasm: it make sense to
         | have a deeper thought about the experiment.
         | 
         | As parent wrote, there may be various reasons for the
         | correlations, sometimes you have random stuff, sometimes
         | indirect stuff and in others extraordinary stuff. Many
         | discoveries (especially older ones) fall into the last
         | category.
        
           | Symmetry wrote:
           | I like the phrasing, "Correlation correlates with causation
           | because causation causes correlations".
        
             | thaumasiotes wrote:
             | Causation frequently removes correlations that would
             | otherwise exist.
        
               | Symmetry wrote:
               | I don't think that's right? In theory you could have A
               | and B that were naturally correlated and add a causal
               | relationship between the two that exactly canceled that
               | correlation but that would be infinity unlikely to happen
               | by chance. In practice the only way that A and B can be
               | correlated is that either A causes B, B causes A, or some
               | C causes both A and B. Interestingly if both A and B
               | cause C the C and A as well as C and B will be correlated
               | but A and B won't be, allowing you to work out causation
               | from a strictly correlational graph.
        
           | acj wrote:
           | > where I read it (probably xkcd)
           | 
           | Yep, it's in the alt text for https://xkcd.com/552/
           | 
           | "Correlation doesn't imply causation, but it does waggle its
           | eyebrows suggestively and gesture furtively while mouthing
           | 'look over there'."
        
           | [deleted]
        
           | Spooky23 wrote:
           | With this sort of thing, lots of social factors weigh in too.
           | Access the flu shots implies regular access to healthcare and
           | perhaps other interventions.
        
         | blagie wrote:
         | The scientists said it was causation.                   "We
         | found that flu vaccination in older adults reduces the risk of
         | developing Alzheimer's disease for several years. The strength
         | of           this protective effect increased with the number
         | of years that a           person received an annual flu vaccine
         | - in other words, the rate           of developing Alzheimer's
         | was lowest among those who consistently           received the
         | flu vaccine every year"
         | 
         | Yes, that's in an interview for the article. That's the reason
         | (1) the general public misunderstands (2) people scream about
         | it. Scientists get points for "high-impact research," and there
         | is strong incentive to be dishonest.
         | 
         | (As a footnote, personally, I do believe it is causation; I
         | believe that as with COVID and EB, we've dramatically
         | underestimated the long-term impact of many viral infections.
         | But that's just a personal belief.)
        
           | itsoktocry wrote:
           | > _The scientists said it was causation._
           | 
           | Interesting. I don't read that as claiming causation, I read
           | that as _describing_ the correlation.
           | 
           | You're right though, it's confusing messaging, regardless.
        
             | [deleted]
        
           | threatofrain wrote:
           | I've always read "protective effect" to be making a
           | predictive statement and not a causal one.
        
           | i_love_limes wrote:
           | In the interview he seems to be more loose with his words,
           | but that also doesn't say causation. In the paper the
           | conclusion is "This study demonstrates that influenza
           | vaccination is associated with reduced AD risk in a
           | nationwide sample of US adults aged 65 and older."
           | 
           | That is distinctly not causal.
        
             | xupybd wrote:
             | Sitting down and talking it's often hard to be as precise
             | as you would like to be. Especially when you don't have
             | time to reflect on the implications of what you've just
             | said.
        
           | spandrew wrote:
           | This is a mischaracterization of even the words you've
           | quoted.
           | 
           | The team did indeed find that flu vaccines reduced the risk
           | of Alzheimers. But he specifically doesn't say they know _why
           | the flu vaccine lowers the risk_. Ie. They can 't claim
           | causation if they don't understand the underlying reason for
           | the change. That's not how science works.
           | 
           | In fact in the article in question he says the opposite: That
           | the immune system is vastly complex, and all they can say is
           | the immune system reacts to flu vaccines (all flu, not just a
           | specific one) by diminishing an Alzheimers response.
           | -\\_(tsu)_/- More study needed plz.
        
       | wonderwonder wrote:
       | Never gotten the flu vaccine before. Biggest fear in life is
       | alzheimers. Guess I will get the flu vaccine annually going
       | forward.
        
         | seydor wrote:
         | Participants in the study were on average 75 years old.
        
           | wonderwonder wrote:
           | My family has an unfortunate history of not living past 65,
           | so may as well start now :)
        
         | wincy wrote:
         | The also allude to "other vaccines" in this article. Googled it
         | and they mean the pneumococcal vaccines also gave a protective
         | effect. So maybe get those. If you just tell your doctor you're
         | an alcoholic they'll give it to you.
        
         | loeg wrote:
         | Worth getting anyway -- the flu is pretty miserable.
        
       | willcipriano wrote:
       | People who get yearly flu vaccines probably go to the doctor more
       | regularly than those who do not. I would expect that people who
       | more regularly go to the doctor are also more concerned about
       | their health. I'd expect people who are concerned with their
       | health to behave in ways that limit disease.
       | 
       | Without a proposed method of action, I suspect this is just
       | noise.
        
         | JumpCrisscross wrote:
         | The researchers controlled for "number of routine well visits
         | during the look-back period, and total number of health care
         | encounters during the look-back period (as a proxy for overall
         | healthcare utilization rate)" [1].
         | 
         | [1] https://content.iospress.com/articles/journal-of-
         | alzheimers-...
        
           | willcipriano wrote:
           | Thank you for the link. That's a interesting population,
           | older people who regularly receive medical care but refuse
           | flu vaccines. I wonder if that is representative of the
           | general population.
        
         | TylerE wrote:
         | Otoh, people who visit the doctor regularly are more likely to
         | be diagnosed
        
         | dcolkitt wrote:
         | Even simpler. Annual flu shots require a decent degree of
         | executive functioning. People with early stage neurological
         | decline are less likely to make or keep their appointment
        
         | synu wrote:
         | There's a section in
         | https://content.iospress.com/articles/journal-of-alzheimers-...
         | called Hypothesized Mechanism(s), which contains (amongst
         | supporting details) the following:
         | 
         | > 1) influenza-specific mechanisms, including mitigation of
         | damage secondary to influenza infection and/or epitopic
         | similarity between influenza proteins and AD pathology; 2) non-
         | influenza-specific training of the innate immune system; and 3)
         | non-influenza-specific changes in adaptive immunity via
         | lymphocyte-mediated cross-reactivity.
        
       | bloodyplonker22 wrote:
       | This article has very few details and is rather questionable, at
       | best. Correlation does not imply causation. It could very well be
       | that people who choose to get flu vaccines are more health-
       | conscious and live a healthier lifestyle so they are less likely
       | to get Alzheimers.
        
         | yeeetz wrote:
         | This is a published journal article that took those covariates
         | into account. Off-hand comments dismissing articles with a
         | correlation vs. causation quip is so expected and tiresome,
         | especially since you can make these comments without reading
         | the actual article.
        
           | bloodyplonker22 wrote:
           | It's interesting how you can condescendingly say "took these
           | covariates into account" without even thinking about how many
           | outside variables there are that they simply cannot take into
           | account because there are obviously too many. Most people
           | don't think too much and just read articles and take anything
           | in writing as the truth.
        
         | i_love_limes wrote:
         | It links to the actual paper if you are interested, the paper
         | has a whole table of covariates it took into consideration.
         | https://content.iospress.com/articles/journal-of-alzheimers-...
         | 
         | I don't think the paper or the journal article suggested it was
         | causal either. But such a correlation with such a large
         | population warrants publication and further research into
         | causation.
         | 
         | You unfortunately chose literally the first thing that any
         | epidemiologist would consider, which is considering potential
         | confounders. Maybe read up a bit before commenting.
        
         | ortusdux wrote:
         | The 3rd paragraph links to the publication that this article is
         | a brief summary of. They controlled for many lifestyle factors
         | in their research.
         | 
         | https://content.iospress.com/articles/journal-of-alzheimers-...
        
       | seydor wrote:
       | A lot of armchair scientists in the comments. It's quite striking
       | effect but why is it published on IOS press? Looks like there
       | might be more worth exploring in that dataset. What are the ways
       | in which their result could be an artifact?
        
       | lancebeet wrote:
       | It's quite remarkable that an effect of this size on such a large
       | group seems to have gone undetected for such a long time. As a
       | layman, I would almost have expected geriatricians to have made
       | the observation during their own practice.
        
         | MuchoMaas wrote:
         | Also quite remarkable that the flu vaccine seems to have a
         | larger impact on the prevalence of Alzheimer's disease than it
         | does on, well, influenza.
        
       | calebm wrote:
       | What a strange and unexpected positive side-effect. Thanks
       | goodness there are no possible unexpected negative side-effects.
        
       | dragontamer wrote:
       | My sister who is a public health specialist, cautioned me about
       | how difficult establishing cause-and-effect in these sorts of
       | discussions can be in general. She hasn't talked to me about this
       | specific case, but lemme bring something up from the perspective
       | that we Computer Scientists can understand.
       | 
       | Cause-and-effect chains form a DAG (Directed Acyclic Graph). For
       | example, A causes B causes C, in theory (or in this case, A
       | causes B prevents C. Cause vs prevent doesn't really matter, its
       | just a negative on the correlation diagrams)
       | 
       | In this case, we want to determine if "Flu Vaccination
       | causes/prevents Alzheimer's Disease".
       | 
       | Now lets consider a bunch of real life factors. Wealth, Age, Sex,
       | Race, Educational Attainment, Insurance. Just the basic stuff
       | anyone would think about. Lets focus on Educational Attainment +
       | Insurance to keep things simple.
       | 
       | * Education -> Flu + Education -> Alzheimer's? Or is it the case
       | that "stronger mind -> Education -> Flu Vaccines" and "stronger
       | mind -> Education -> Alzheimer's" ?? Education is almost
       | certainly a conflating situation (Education would probably cause
       | higher flu vaccine uptake, and simultaneously would reduce
       | Alzheimers), so maybe the Flu vaccine isn't causing the effect...
       | but is instead just a cross-correlation to education level.
       | 
       | * Insurance probably causes flu-vaccines (because flu vaccines
       | are free for most insurance plans). Insurance probably doesn't
       | cause/prevent Alzheimer's though. So we have "Insurance -> Flu-
       | vaccine -> Alzheimer", which means we don't have to worry about a
       | cross-correlation in this case.
       | 
       | --------
       | 
       | Etc. etc.
       | 
       | Basically: to truly understand if we have a cause-and-effect
       | situation here, we need to think of all possible conflating
       | factors (such as education), while discounting factors that are
       | "along" the DAG-chain towards the hypothetical result (ex:
       | Insurance).
       | 
       | After that, there's apparently a lot of math and analysis that we
       | can do. If we take the records of the people who participated in
       | this study, and get their educational levels + insurance
       | information, we can then account for these conflating factors.
       | 
       | I probably messed up the language and everything else for that
       | matter. But just a reminder that public health discussions are
       | rather technical. There's both a science and an art to the whole
       | process, and just reading the "results in the raw" could lead to
       | a misunderstanding.
       | 
       | ----------
       | 
       | The best example of this is "Ice Cream causes Drowning". (Real
       | life: Hot summer temperatures cause ice-cream consumption. Hot
       | summer temperatures cause people to swim.) We need to account for
       | the Hot-temperature effect if we want to find the truth behind
       | that correlation.
       | 
       | There's also the chance that we've got it all backwards.
       | Alzheimer's causes people to stop taking the flu vaccine. (IE:
       | Alzheimer's might cause people to be more easily swayed by anti-
       | vax propaganda, causing them to take less flu vaccines)
       | 
       | Figuring out all possibilities (as well as possibilities that
       | aren't even listed) is the job of a public health care
       | specialist. They'll get it wrong, but hopefully less wrong than
       | you or I would. There's apparently mathematical techniques to be
       | used to tackle each of these questions I brought up.
        
         | JumpCrisscross wrote:
         | > _lets consider a bunch of real life factors. Wealth, Age,
         | Sex, Race, Educational Attainment, Insurance. Just the basic
         | stuff anyone would think about_
         | 
         | The study measured an extensive list of covariates [1]. The
         | data source, "medical claims, pharmacy claims, administrative
         | claims, and laboratory result data for privately insured or
         | Medicare Advantage with Part D enrollees who have both medical
         | and prescription-drug coverage" [2], excludes the uninsured and
         | those without Medicare Part D, so that's not a confounder.
         | 
         | I'm having trouble finding a bias that would create this effect
         | size other than reverse causation, _i.e._ people developing AD
         | forget to get their flu shots.
         | 
         | [1] https://content.iospress.com/download/journal-of-
         | alzheimers-...
         | 
         | [2] https://content.iospress.com/articles/journal-of-
         | alzheimers-...
        
           | dragontamer wrote:
           | That's indeed, a very impressive list of covariates factored
           | in here.
           | 
           | Hmmm... figuring out a possible mistake would require quite a
           | bit of creativity. Creativity that's beyond my abilities at
           | least, lol.
           | 
           | Note that having such a list hampers a lot of "creative"
           | attempts to take down the study. For example, Tobacco Use is
           | very clearly related to the Republican/Democrat divide, and
           | is therefore an adequate stand-in for the effects of
           | political views (in case political views have an effect on
           | flu-vaccinations / Alzheimer's).
           | 
           | So anything "correlated" to these other covariates (ex: Red
           | vs Blue states vs Tobacco) is "already factored in". As such,
           | having a very, very big list like this helps dramatically.
        
       | jeffreportmill1 wrote:
       | Possible alternate title: "People with early onset Alzheimer's
       | frequently forget to get flu shots".
        
         | ac29 wrote:
         | Given that >90% of non-vaccinated patients did not get a
         | Alzheimer's diagnosis, this seems wrong.
        
       | ajaimk wrote:
       | There is a joke here about forgetting to get your flu vaccine
        
       | bilsbie wrote:
       | I posted this exact link two days ago. What gives?
        
         | kelnos wrote:
         | I wouldn't think anything nefarious happened. A few
         | possibilities:
         | 
         | * You posted it during a time of day when the site receives
         | less traffic, and it scrolled too far down or off the New page
         | for people to see it and vote it up. (Looks like you posted
         | during lunch time on the US west coast, so maybe this isn't
         | likely.)
         | 
         | * When you posted, there was other big news or something going
         | on that people were absorbed in, and didn't notice your post.
         | 
         | * Some don't visit HN multiple times a day, and perhaps you
         | just got unlucky that many of the people who would have found
         | this interesting didn't see it 2 days ago, but did happen to be
         | around today.
         | 
         | * Your account was created three days ago, and I wouldn't be
         | surprised if HN doesn't weight upvotes on new-account
         | submissions as highly as for older accounts. Also consider that
         | your first submission (the day before) was flagged and killed;
         | that might put you in a time-limited penalty box. (I don't know
         | any of this for a fact, as I have no idea how HN's software
         | works, but it seems plausible.)
         | 
         | * Just dumb luck. I've made a bunch of submissions that I
         | thought were interesting (and though would appeal to a wide
         | variety of HN readers/commenters), but it just turned out that
         | it wasn't the case. Maybe it was just timing or something else.
         | 
         | I believe the mods have stated that HN allows duplicate links
         | within a shorter-than-normal time period if the previous
         | posting didn't get much attention, so it's perhaps not
         | surprising that the software allowed the repost.
        
       | eganist wrote:
       | The correlation is probably loosely causative based on other
       | research pointing to certain infections preceding a descent into
       | Alzheimer's or Dementia.
       | 
       | Related (not exhaustive. The infectious theory is rapidly gaining
       | ground especially in light of anti-beta-amyloid drugs repeatedly
       | failing in clinical trials):
       | 
       | * HSV/Alzheimer's:
       | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8234998/
       | 
       | * HSV/Alzheimer's: https://content.iospress.com/articles/journal-
       | of-alzheimers-...
       | 
       | * HSV/Alzheimer's: https://pubmed.ncbi.nlm.nih.gov/29488144/
       | (current independent phase 2 trial to reproduce outcomes:
       | https://clinicaltrials.gov/ct2/show/NCT03282916)
       | 
       | * Gingivitis/Alzheimer's:
       | https://pubmed.ncbi.nlm.nih.gov/32280099/
       | 
       | * Immunological role of Beta-Amyloid: https://alz-
       | journals.onlinelibrary.wiley.com/doi/full/10.100...
        
       | srvmshr wrote:
       | At some point we (researchers & scientists) should draw the line
       | between correlation & causation.
       | 
       | That there is 40% less incidence in flu vaccinated patients is
       | established by observation, but is it due to flu vaccine by
       | itself or factors which surrounds itself in people more prone to
       | flu or who are medically more conscious? (edit: think of analysis
       | of variance tests among identifiable medical & socioeconomic
       | variables). If the researchers establish a positive link,
       | wouldn't it be worthwhile to then suppose that amyloid plaques
       | are somehow related to viral influenza replication - which by
       | itself sounds a bit absurd (edit: Ok lot of good reference about
       | infections around AD. I take this back, my bad)
       | 
       | The alternative hypothesis is worth thinking too: Are people more
       | prone to Alzheimer's also more prone to catching flu.
        
         | JumpCrisscross wrote:
         | > _wouldn 't it be worthwhile to then suppose that amyloid
         | plaques are somehow related to viral influenza replication -
         | which by itself sounds a bit absurd_
         | 
         | This is a prominent theory for the cause of Alzheimer's disease
         | [1].
         | 
         | [1] https://news.ycombinator.com/item?id=31900354
        
         | lukev wrote:
         | At some point we (commenters on hacker news) should stop
         | reflexively typing this in response to every study without
         | reading the paper.
         | 
         | From the abstract:
         | 
         | > Propensity-score matching (PSM) was used to create flu-
         | vaccinated and flu-unvaccinated cohorts with similar baseline
         | demographics, medication usage, and comorbidities.
         | 
         | If you want to argue that the authors did a bad job at this,
         | for some reason, that would be a really meaningful contribution
         | and I'd love to hear the details.
         | 
         | Otherwise, can we assume that the scientists writing and
         | reviewing papers did a semi-competent job and are _at least_ as
         | good at analyzing quantitative claims as someone commenting on
         | HN because they are bored at work?
        
           | srvmshr wrote:
           | I am not an expert at this, though I have taken few credits
           | of Biostatistics. I would be more interested if swapping the
           | variables also gave significance in tests. Did the
           | Alzheimer's cohort also have a higher incidence of flu
           | related comorbidities? I understand this is difficult - but
           | this is why ANOVA tests also are extensively used to show
           | variable dependence or report the degree of dependence. It is
           | unclear from their findings. Without that we are probably
           | looking at some positive correlation without investigating
           | the causation.
        
           | nazka wrote:
           | But virtual HN karma points are so juicy! /s
           | 
           | Sometimes HN can do this or turn simple topics into some
           | crazy meta stuff... I'm telling you so many times some
           | comments look like what I will find in a parody of HN and/or
           | bring no real value to the discussion but are so articulated
           | and counter arguing and expanding and what not. Heck half of
           | the times those comments start a new paragraph mid comment
           | with << Heck... >>. And they all look the same. /renting
        
             | rzzzt wrote:
             | Hey, I can add all the references so noone else has to:
             | 
             | - http://www.tylervigen.com/spurious-correlations
             | 
             | - https://xkcd.com/882/
             | 
             | - (honorable mention: https://xkcd.com/552/ - gets cited
             | less often but is relevant nonetheless)
        
             | srvmshr wrote:
             | Maybe you should look into specifics of what exactly I am
             | asking as the question, before terming it "crazy meta
             | stuff". I am trying asking valid questions, which may be
             | wrong or someone will explain it better clearing my
             | misconception. I will learn something new & be grateful.
             | Win-win
             | 
             | What is your contribution by this rant exactly, except
             | making yourself look absurd?
        
       | standardUser wrote:
       | If anyone out there thinks there are still people who don't
       | realize that "correlation does not equal causation", don't worry,
       | we all know.
        
         | bink wrote:
         | Now you just have to convince them that scientists know how to
         | control for these effects.
        
       | lukev wrote:
       | Lots of discussion in this thread about the _accuracy_ of the
       | implied claim  "vaccination can prevent Alzheimers", but not a
       | lot about the correct course of action.
       | 
       | Which seems to me to be, unambiguously, you should _absolutely_
       | be religious about getting your flu shot every year. The vaccine
       | is known to be safe and with few side effects (or at least, safer
       | than the actual flu, which is the bar that needs to be cleared.)
       | 
       | And even if it hasn't been conclusively _proven_ that vaccines
       | can avert Alzheimer 's, you're at least putting yourself in the
       | best possible cohort, right? Anyone familiar with Bayes' Theorem
       | should be absolutely on board with this.
        
         | runevault wrote:
         | I will say, as someone with an egg allergy it isn't so black
         | and white. Not everywhere carries alternative ways of getting
         | flu vaccine, though hopefully post Covid mRNA versions will
         | become more prevalent (assuming that version has the same
         | impact, haven't read the article).
        
         | ekianjo wrote:
         | This seems like a dubious recommendation. In Japan there is a
         | large acceptance of yearly flu shots yet Alzheimer s prevalence
         | remains high.
        
           | ksb wrote:
           | Perhaps not. See this article:
           | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4095986/
           | 
           | > _Among developed countries, Japan has the lowest prevalence
           | of both dementia in general and Alzheimer 's disease in
           | particular._
        
       | gojomo wrote:
       | The words "linked to" or "associated with" are tells that no real
       | causality has been established - no matter how casually, or
       | sloppily, causality is implied by the paper or breezy PR
       | summaries.
       | 
       | Maybe, early pre-diagnosis aspects of eventual Alzheimer's (such
       | as undiagnosed mild cognitive impairments) makes people less
       | interested in, and diligent in pursuing, flu vaccinations. (In
       | other words: the causality goes the other way.)
       | 
       | But also, people with active family/social lives are both more
       | likely to be reminded to get a flu vaccine, and less likely to
       | develop Alzheimer's.
       | 
       | And further: more conscientious people seek out vaccines. More
       | conscientious people get Alzheimer's at a much lower rate. For
       | example, this study -
       | https://jamanetwork.com/journals/jamapsychiatry/fullarticle/... -
       | suggests those in the 90th percentile of conscientiousness have
       | 89% lower rates of Alzheimer's diagnoses than those in the 10th
       | percentile of conscientiousness.
       | 
       | While a mechanism from vax-induced immunity, and/or fewer actual
       | infections, to less dementia is plausible, these other well-known
       | correlates/confounders seem a likely explanation for these
       | results, until/unless controlled-for.
        
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