An extremely simple hypothesis: The world of today is more cognitively demanding. To take a very simple empirical example, 7% of 25 year olds had a college degree in 1960, 36% in 2020! You have to wonder what the neuroprotective effects are of being able to write an essay, analyze a novel, perform a chemical experiment, prove a theorem, whatever, over a lifetime. But it's well-established that the brain, like all other organs of the body, is "use it or lose it."
gwbas1c · 13h ago
A while back I read Silent Spring, and the author made an interesting note: Pesticides used in the 1960s were neurotoxins, and she feared that they could cause neurological disorders. We now use different pesticides.
JumpCrisscross · 13h ago
> Pesticides used in the 1960s were neurotoxins, and she feared that they could cause neurological disorders. We now use different pesticides
The "younger generations" in this study were born between 1944 and 1948. (Older, 1890 to 1913.) Pesticides don't explain why those born in the former have less dementia than those born between 1939 and 1943.
cogman10 · 13h ago
They do if the effects are cumulative.
They additionally cite in the article that perhaps it's smoking that's changed, yet that also didn't really significantly change in public until the 90s.
40 additional years of pesticides/lead/smoking/etc will take their toll.
dragonwriter · 13h ago
> They additionally cite in the article that perhaps it's smoking that's changed, yet that also didn't really significantly change in public until the 90s.
Prevalence of smoking in the US peaked at around 45% in the 1950s, and had dropped to around 25% by the 1990s. (Depending on your own age, this may feel wrong because there was a surge in youth smoking from the 80s peaking in the mid-1990s, so its easy for people in a certainnage range to feel like smoking was very prevalent through the 1990s, and then dropped like a rock.)
JumpCrisscross · 12h ago
> Prevalence of smoking in the US peaked at around 45% in the 1950s, and had dropped to around 25% by the 1990s
Wouldn't you expect to see more variation between the American and European cohorts if smoking were the culprit?
AbstractH24 · 8h ago
And while smoking has plummeted, nicotine usage is resurgent
As is smoking of other things
noleary · 3h ago
Interestingly, there's reasonably good basis to suspect nicotine (though not smoking) can reduce rates of neurodegenerative disease like Alzheimer's and Parkinson's.
daedrdev · 4h ago
Of course nicotine addiction is one problem and putting ash in your lungs is another
adastra22 · 1h ago
I expect the two world wars & a Great Depression might have more to do with it than pesticides or leaded gasoline.
Eric_WVGG · 2h ago
this is a thousand percent due to lead
userbinator · 40m ago
The younger generations would've been exposed to much more leaded gasoline per body mass when they were young, whereas the older generations were already at least young adults by the time leaded became commonplace.
PantaloonFlames · 5h ago
I would think pesticides in the 1890’s through 1930’s were not as dangerous as what came later.
Is that a poor assumption?
cogman10 · 4h ago
It is, mainly because the history of pesticide research has basically been looking for the least harmful pesticides to humans.
Before DDT went into wide use in the 1940s, aersnic based pesticides were common.
Here's a particularly nasty one that was commonly used up until DDT replaced it.
My great-grandma is the only one in my family who died of cancer and she used to apply farm chemicals by hand
exe34 · 13h ago
Very loose speculation as a non-biologist. Could it have been that most of the healthy males (e.g. good testosterone levels, and whatever else made virile young males) were away at war, and the men left to father children had some sort of deficiency which also correlates with better protection against dementia?
nartho · 13h ago
Probably not. you'd have to prove that people who were able bodied in their youth are less likely to have dementia than people with disabilities or bad physical health. To my knowledge there is no such link. Besides, a big part of this sample was from the US who didn't enter the war before the very end of 41 (December 7th so might as well be 1942). Occupied Europe also didn't really have it's men "away at war". Also, men at war, even during WW1, were able to go back home from time to time, so I don't think the argument holds.
JumpCrisscross · 12h ago
> a big part of this sample was from the US who didn't enter the war before the very end of 41 (December 7th so might as well be 1942). Occupied Europe also didn't really have it's men "away at war"
The nail in the coffin for the hypothesis is the lack of significant variation between the US and European cohorts. Europeans were killed indiscriminately. Our men were selectively slaughtered. If there was a selection effect, you'd expect that to present in the American cohorts and not European ones; that is not observed.
colechristensen · 3h ago
Most pesticides are still neurotoxins, they're just somewhat better targeted towards insects.
Most flavor compounds in herbs and spices are also neurotoxins, coffee and chocolate contain many neurotoxins, nearly every naturally occurring stimulant or psychoactive substance humans use is a neurotoxins targeting a different creature. We happen to find many of them pleasant or tasty because they evolved to target very distant relatives or we are just weirdos that find mildly poisoning ourselves fun.
Silent Spring leaned far too much on fear and exaggeration which is a disservice to the much more complicated issues we face with synthetic chemistry and controlling our environment.
bsder · 3h ago
More likely vaccines, antibiotics, and public health initiatives/nutrition.
Diseases (and especially virii) are showing to leave behind WAY more damage than everybody thought. Nutritional stress leaves behind lasting damage as well.
The early cohort being compared went through the Spanish Flu and the Great Depression. Who knows how much damage those left?
While we're speculating as to causes obstructive sleep apnea is associated with dementia, estimates are that 30 million people have it, and we only invented CPAPs in 1980.
pedalpete · 7h ago
The prevalence of apnea is likely highly over-estimated. ResMed and Philips, who both make billions off of CPAP, push these high figures.
Measures of OSA (Obstructive sleep apnea) are somewhat poor, more focused on the amount of pauses in breathing, rather than oxygen desaturation, which is the secondary measure. Note, you don't breath 100% of the time when you're awake either.
I work in sleep and neurotech, and at a large sleep conference last year, a talk was given about better methods to measure apnea. It was clear these measures would have significant challenges in being adopted because it would result in less people being diagnosed as needing CPAP.
Lastly, the impact of CPAP in improving cognitive function is inconclusive [1]. Not that it doesn't have an affect. It does in some people, but not in others.
Did anyone report on reductions in sleep apnea due to GLP-1s ? I would imagine that the introduction of effective weight loss meds en masse might change the trajectory of more than a few sleep apnea sufferers
bhouston · 13h ago
Are cpaps that widely used to have that significant of an effect?
For CPAP to be primarily responsible, we would need a very sizeable portion of the population to be using them, but I think the numbers are less than 3% right?
From the article as to the effect size:
“For example, in the US, among people aged 81 to 85, 25.1% of those born between 1890–1913 had dementia, compared to 15.5% of those born between 1939–1943,”
I'm not saying that CPAPs don't contribute, but they are not likely the main contributors.
alargemoose · 7h ago
I think you have this backwards. OP is saying sleep apnea is common, but we’ve only had CPAP machines to compensate for it, since the 80s. I don’t see them trying to implicate CPAP as the cause of an increase in dementia.
Someone · 1h ago
I think bhouston is arguing (correctly) you can’t have a 10% of the population drop in dementia prevalence by an intervention that only targets 3% of the population, so even if CPAPs contribute, that does not explain most of the drop.
(If everybody who uses CPAPs would get dementia, and they are 100% effective at preventing that, the drop would still be ‘only’ 3% of the population)
sokoloff · 6h ago
I read that as saying that 3% CPAP usage couldn’t explain a 10% drop in dementia.
aantix · 12h ago
I wonder if sleep apnea diagnoses will decrease with the increasing use of GLP-1s?
Zepbound is FDA-approved for OSA.
jaggederest · 47m ago
It 100% will. Interestingly zepbound does more than merely lower weight and thus reduce sleep apnea as a secondary result, it seems to actually help directly from the preliminary studies I've read, much like we're seeing in other domains where GLP-1 drugs actually reduce e.g. fatty liver disease more than the same amount of weight loss alone.
I wonder if we'll discover that there's actually an endemic deficiency in endogenous GLP-1 production due to some other cause? The usual suspects of environmental contamination or subclinical infection, perhaps.
mike-the-mikado · 12h ago
Isn't sleep apnea associated with obesity, which undoubtedly has been increasing?
m-schuetz · 2h ago
There is also a reverse causality that's often overlooked - People getting obese because they develop sleep apnea. Happened to a relative. Developed allergy-related sleep apnea resulting in significantly reduced sleep quality and quality of life. Was often awake until after midnight due to trouble falling asleep from breathing issues that occured when nose and throat would start to relax. After about two years of this, he let himself go and gain 15kg over the coarse of a single year.
reverendsteveii · 11h ago
yes, but in one case we're talking about OSA causing dementia and in the other we're talking about obesity causing OSA
jajko · 13h ago
Dude, global estimate for OSA is in the range of 1 billion, its a global pandemic
mike-the-mikado · 12h ago
I think that head injuries are a known cause of dementia (my father suffered a serious head injury and developed dementia a few years later at the age of about 70). It has been implicated in connection with sports injuries (boxing, rugby, heading a ball).
I wonder if the risk of head injury has reduced with time?
JumpCrisscross · 12h ago
> head injuries are a known cause of dementia
Almost 2x more likely [1].
> wonder if the risk of head injury has reduced with time?
The lack of spikes from the world wars would suggest otherwise.
My dad's hobby when I was a kid was playing the saxophone.
Bunch of wind instrument legends started dying relatively young around that time, and he went "yeah… no."
(Granted, he wasn't doing drugs and alcohol like musicians probably do, but it was still enough to scare him away.)
mullingitover · 13h ago
It's gonna be, at least in part, vaccines[1]. If we invented drugs today that did what routine vaccinations did for Alzheimer's prevention, it would be hailed as a medical miracle.
> Patients who received the Tdap/Td vaccine were 30% less likely than their unvaccinated peers to develop Alzheimer’s disease (7.2% of vaccinated patients versus 10.2% of unvaccinated patients developed the disease). Similarly, HZ vaccination was associated with a 25% reduced risk of developing Alzheimer’s disease (8.1% of vaccinated patients versus 10.7% of unvaccinated patients). For the pneumococcal vaccine, there was an associated 27% reduced risk of developing the disease (7.92% of vaccinated patients versus 10.9% of unvaccinated patients).
I am actually very interested to see the data play out with the first generation of people who received the chickenpox vaccine as kids (millennials). If you have chickenpox, then you're at risk for shingles later in life, which seems to be a contributing factor to dementia in some individuals. But if an entire generation isn't at risk of shingles, we would probably expect to see a statistically significant drop in dementia as well.
_DeadFred_ · 12h ago
Random thought. Do antibiotics kill any sort of permanent seemingly benign outside bacteria in the body? Did we historically have more ongoing internal invaders than we do now because we now have antibiotics? I guess I'm asking did we used to have persistent, ongoing infections that now get wiped out every so often as a side effect of taking antibiotics?
Vrondi · 12h ago
Not just antibiotics to consider along this line of thought. We historically had a higher load of parasites. Far more of the population had some amount of parasites more of the time. Things like sewer systems/sanitation/clean drinking water/bathing and personal hygiene/wearing shoes/not having piles of animal feces all over the streets. That all changed the amount of exposure to parasites for the common person. We know it affected our immune systems (overall rates of allergies increased). We do not know how it affected our brains. Makes intuitive sense that it must apply to bacteria as well. Before foods were pasteurized (and before refrigeration), for example, we were exposed to more dietary sources for bacteria, both beneficial and non-beneficial.
pinkmuffinere · 13h ago
That’s super interesting! From the first line I thought this comment was going to go the other way, lol…
SoftTalker · 12h ago
Still hard to draw conclusions. It could be that people who get all the recommended vaccines are just in general more health-conscious and this has some relationship to dementia risk.
JumpCrisscross · 12h ago
> could be that people who get all the recommended vaccines are just in general more health-conscious and this has some relationship to dementia risk
Huh, it looks deeper than mere correlation [1][2].
The simple explanation is inflammation. The intriguing potential is the vaccines train the immune system to clear something harmful.
EDIT: It looks like some HSV antibodies also attack various Alzheimer's-related compounds, including "Aß protein, tau protein, presenilin, rabaptin-5, β-NGF, BDNF, mTG, and enteric nerve" [3]. Wild. I wonder if there is a link between the vaccination status of a mother and childhood dementia presentation.
The interesting thing about dementia is that it is not normally distributed whatsoever. Pick basically any characteristic imaginable - environmental, behavioral, or genetic, and you're going to find a difference, often very significant, between groups.
Everything from your occupation, to your diet, to martial status, to hobbies, and much more have been shown to have significant relationships with dementia rates. The problem you obviously run into here is that a person's approach towards healthcare is itself a major behavioral characteristic and so seeing varying rates of dementia based on this characteristic alone would be very unsurprising.
JumpCrisscross · 12h ago
> seeing varying rates of dementia based on this characteristic alone would be very unsurprising
Sure. That's why the antibody cross-reactivity is intriguing.
somenameforme · 3h ago
You're begging the question. While endless things are associated with dementia (or its absence) nobody knows what causes it, and so looking for causal reasons with behavioral characteristics is going to mislead without carefully controlled experimental (and not observational) studies.
mullingitover · 12h ago
The shingles vaccine is another promising one[1]
> Researchers found that compared to those who didn't get the shingles vaccination, those who received it...
> were 3.5% less likely to develop dementia over seven years (a 20% reduction)
These types of findings are problematic for anti-vaxxers, however they seem likely to overcome this through their wholesale butchery of US research.
I think it's going to be very interesting to see what kind of effects long term antiretrovirals for HIV treatment and prevention have. Surely they're not so tightly targeted that they only affect HIV, so it'll be interesting to see which conditions they prevent and which they cause, since we've got tons of people on them for a quarter century now or so.
I also wonder this kind of thing about other long term treatments - perhaps Prozac prevents dementia, or causes it.
Ifkaluva · 13h ago
Would be a crazy plot twist if social media and doomscrolling were protective against dementia
mentos · 13h ago
Aren’t puzzles recommended for the elderly to keep their minds active?
Curious to see how a lifetime of nonstop digital interactive puzzles leaves us. (Video games)
lagniappe · 12h ago
This is the most egregious rationalization of the Capcha dystopia I've ever seen.
akimbostrawman · 11m ago
Billion dollar idea right there. Why pay third world countries to solve them when the elderly could do it for free to there own benefit.
whynotminot · 5h ago
Captcha… the whole time it was the true bicycle for the mind
bsimpson · 2h ago
Please select the squares that contain the bicycle for the mind.
opan · 13h ago
This would make for a neat study considering all the different genres of video games. I imagine they wouldn't all have an equal effect.
gruez · 7h ago
How is scrolling through videos on tiktok better than flipping through channels on a TV?
UncleOxidant · 11h ago
somehow I suspect it's going to be the opposite.
georgeburdell · 13h ago
The article doesn’t seem to posit one single cause, but anecdotally, the people in my family with dementia were women. One got it from smoking. Three others had Alzheimer’s. The one who had it least bad was the one who had a job other than housewife
n1b0m · 13h ago
“Women have a greater risk of developing dementia during their lifetime. The main reason for this is thought to be because women live longer than men. Age is the biggest risk factor for dementia so living longer means that the risk of developing it is greater.”
Unfortunately my mom developed dementia in her late 60s. Not exactly old. I’ve wondered if covid triggered the onset. Her husband was/is a covid denier though he had it three times and almost died once. My mom never had a bad case of Covid, but was exposed many times.
pedalpete · 7h ago
Women are twice as likely as men to get Alzheimer's.
The two current prevailing theories are, both of which focus on the amyloid hypothesis are
1) menopause changes in grey matter reduce the glymphatic systems ability to flush metabolic waste from the brain
2) sleep loss during child-rearing and menopause result in increased amyloid load, which begins the cycle of reduced ability of the glymphatic system to remove waste from the brain.
I know someone is going to come in complaining about the amyliod hypothesis, but it is unlikely to be "wrong", it is just incomplete. We are likely lumping multiple different diseases together under the label of Alzheimer's because we don't understand the disease well enough yet.
missedthecue · 5h ago
Interestingly, research, including UK biobank data with massive sample sizes, has proven many times that childless women are at considerably higher risk for dementia and Alzheimer's than women with 1-4 children.
pedalpete · 3h ago
I hadn't seen that. I'll take a closer look. Thanks
vjvjvjvjghv · 13h ago
In my family it’s the other way around. It’s very worrisome that both my father and grandfather had dementia.
RyanOD · 12h ago
Same here. It's like a specter always one step behind me.
gwbas1c · 13h ago
How do you get dementia from smoking?
JumpCrisscross · 13h ago
"Smoking increases the risk of vascular problems (problems with the heart and blood vessels). These vascular problems are also linked to the two most common forms of dementia: Alzheimer's disease and vascular dementia.
Toxins in cigarette smoke also cause inflammation and stress to cells, which have both been linked to Alzheimer's disease."
thanks for this
link: they're interesting to mid 50s me, who never smoked, but whose dad did smoke for decades, and his memory started failing late 80s, i'd never seen it. useful link.
toast0 · 13h ago
I don't know how you determine causality of dementia. But smoking leads to poor heart and lung health and function, and that's got to have follow on effects on brain health. And there's correlation linking smoking to dementia [1]. So, I think it's fair to say grandma smokes a lot who had dementia got it from smoking even without a specific link.
The vascular damage seems to be the main suspect. But I also wonder if smoking causes poor sleep due to it being a stimulant. Poor sleep leads to dementia.
math_dandy · 5h ago
How was smoking identified as the cause’s of dementia in the individual you mention?
Interesting to see they are rating dementia as the 7th leading cause of death[1]. In Australia the common understanding is Alzheimer's is currently the 2nd and will likely claim the 1st spot in the next decade [2].
The study seems to go against everything else I've seen which suggests that as people are living longer, the incidence are increasing, not decreasing. However, my understanding is that as we get better at curing cancers, reducing heart-disease, and generally increasing life-span, the longer a person lives, the more likely they are to get dementia.
Unclear. The cohort most exposed to atmospheric lead was born between 1951 and 1980 [1]. This study only measures those born before 1948.
(To the extent the study supports a hypothesis, it's the null. Given atmospheric lead increased from 1890 onwards, until about the 1980s [2], if lead were the culprit we'd expect to see more dementia among the study's younger generations. Not less.)
Cars only fully replaced horses after WW2, so they were the first universally exposed generation, if anything.
gwbas1c · 13h ago
Personally, I think it's some other pollutant.
That being said, there's some remarkable correlations with bans on leaded gasoline.
olddustytrail · 13h ago
The man who invented leaded gasoline - Thomas Midgley Jr. - also invented CFCs.
He's been referred to as a "one man environmental disaster".
SoftTalker · 12h ago
Two things we know for sure now, and probably knew pretty well even then, chlorinated hydrocarbons and heavy metals are not good for the environment. They have their industrial uses but need to be used with care.
The "younger generations" in this study were born between 1944 and 1948. (Older, 1890 to 1913.) Pesticides don't explain why those born in the former have less dementia than those born between 1939 and 1943.
They additionally cite in the article that perhaps it's smoking that's changed, yet that also didn't really significantly change in public until the 90s.
40 additional years of pesticides/lead/smoking/etc will take their toll.
Prevalence of smoking in the US peaked at around 45% in the 1950s, and had dropped to around 25% by the 1990s. (Depending on your own age, this may feel wrong because there was a surge in youth smoking from the 80s peaking in the mid-1990s, so its easy for people in a certainnage range to feel like smoking was very prevalent through the 1990s, and then dropped like a rock.)
Wouldn't you expect to see more variation between the American and European cohorts if smoking were the culprit?
As is smoking of other things
Is that a poor assumption?
Before DDT went into wide use in the 1940s, aersnic based pesticides were common.
Here's a particularly nasty one that was commonly used up until DDT replaced it.
https://en.wikipedia.org/wiki/Lead_hydrogen_arsenate?wprov=s...
The nail in the coffin for the hypothesis is the lack of significant variation between the US and European cohorts. Europeans were killed indiscriminately. Our men were selectively slaughtered. If there was a selection effect, you'd expect that to present in the American cohorts and not European ones; that is not observed.
Most flavor compounds in herbs and spices are also neurotoxins, coffee and chocolate contain many neurotoxins, nearly every naturally occurring stimulant or psychoactive substance humans use is a neurotoxins targeting a different creature. We happen to find many of them pleasant or tasty because they evolved to target very distant relatives or we are just weirdos that find mildly poisoning ourselves fun.
Silent Spring leaned far too much on fear and exaggeration which is a disservice to the much more complicated issues we face with synthetic chemistry and controlling our environment.
Diseases (and especially virii) are showing to leave behind WAY more damage than everybody thought. Nutritional stress leaves behind lasting damage as well.
The early cohort being compared went through the Spanish Flu and the Great Depression. Who knows how much damage those left?
While we're speculating as to causes obstructive sleep apnea is associated with dementia, estimates are that 30 million people have it, and we only invented CPAPs in 1980.
Measures of OSA (Obstructive sleep apnea) are somewhat poor, more focused on the amount of pauses in breathing, rather than oxygen desaturation, which is the secondary measure. Note, you don't breath 100% of the time when you're awake either.
I work in sleep and neurotech, and at a large sleep conference last year, a talk was given about better methods to measure apnea. It was clear these measures would have significant challenges in being adopted because it would result in less people being diagnosed as needing CPAP.
Lastly, the impact of CPAP in improving cognitive function is inconclusive [1]. Not that it doesn't have an affect. It does in some people, but not in others.
[1] https://www.sciencedirect.com/science/article/abs/pii/S13899...
For CPAP to be primarily responsible, we would need a very sizeable portion of the population to be using them, but I think the numbers are less than 3% right?
From the article as to the effect size:
“For example, in the US, among people aged 81 to 85, 25.1% of those born between 1890–1913 had dementia, compared to 15.5% of those born between 1939–1943,”
I'm not saying that CPAPs don't contribute, but they are not likely the main contributors.
(If everybody who uses CPAPs would get dementia, and they are 100% effective at preventing that, the drop would still be ‘only’ 3% of the population)
Zepbound is FDA-approved for OSA.
I wonder if we'll discover that there's actually an endemic deficiency in endogenous GLP-1 production due to some other cause? The usual suspects of environmental contamination or subclinical infection, perhaps.
I wonder if the risk of head injury has reduced with time?
Almost 2x more likely [1].
> wonder if the risk of head injury has reduced with time?
The lack of spikes from the world wars would suggest otherwise.
[1] https://karger.com/ned/article-pdf/56/1/4/3752570/000520966....
But generally, bullets, disease, and malnutrition don't cause the same sort of brain trauma.
https://newsroom.uw.edu/news-releases/blast-related-concussi...
Bunch of wind instrument legends started dying relatively young around that time, and he went "yeah… no."
(Granted, he wasn't doing drugs and alcohol like musicians probably do, but it was still enough to scare him away.)
> Patients who received the Tdap/Td vaccine were 30% less likely than their unvaccinated peers to develop Alzheimer’s disease (7.2% of vaccinated patients versus 10.2% of unvaccinated patients developed the disease). Similarly, HZ vaccination was associated with a 25% reduced risk of developing Alzheimer’s disease (8.1% of vaccinated patients versus 10.7% of unvaccinated patients). For the pneumococcal vaccine, there was an associated 27% reduced risk of developing the disease (7.92% of vaccinated patients versus 10.9% of unvaccinated patients).
[1] https://www.uth.edu/news/story/several-vaccines-associated-w...
Huh, it looks deeper than mere correlation [1][2].
The simple explanation is inflammation. The intriguing potential is the vaccines train the immune system to clear something harmful.
EDIT: It looks like some HSV antibodies also attack various Alzheimer's-related compounds, including "Aß protein, tau protein, presenilin, rabaptin-5, β-NGF, BDNF, mTG, and enteric nerve" [3]. Wild. I wonder if there is a link between the vaccination status of a mother and childhood dementia presentation.
[1] https://www.nature.com/articles/s41591-024-03201-5
[2] https://pubmed.ncbi.nlm.nih.gov/33856020/
[3] https://pmc.ncbi.nlm.nih.gov/articles/PMC6032666/
Everything from your occupation, to your diet, to martial status, to hobbies, and much more have been shown to have significant relationships with dementia rates. The problem you obviously run into here is that a person's approach towards healthcare is itself a major behavioral characteristic and so seeing varying rates of dementia based on this characteristic alone would be very unsurprising.
Sure. That's why the antibody cross-reactivity is intriguing.
> Researchers found that compared to those who didn't get the shingles vaccination, those who received it...
> were 3.5% less likely to develop dementia over seven years (a 20% reduction)
These types of findings are problematic for anti-vaxxers, however they seem likely to overcome this through their wholesale butchery of US research.
[1] https://www.health.harvard.edu/blog/can-a-routine-vaccine-pr...
I also wonder this kind of thing about other long term treatments - perhaps Prozac prevents dementia, or causes it.
Curious to see how a lifetime of nonstop digital interactive puzzles leaves us. (Video games)
https://www.alzheimers.org.uk/blog/why-dementia-different-wo...
The two current prevailing theories are, both of which focus on the amyloid hypothesis are
1) menopause changes in grey matter reduce the glymphatic systems ability to flush metabolic waste from the brain
2) sleep loss during child-rearing and menopause result in increased amyloid load, which begins the cycle of reduced ability of the glymphatic system to remove waste from the brain.
I know someone is going to come in complaining about the amyliod hypothesis, but it is unlikely to be "wrong", it is just incomplete. We are likely lumping multiple different diseases together under the label of Alzheimer's because we don't understand the disease well enough yet.
Toxins in cigarette smoke also cause inflammation and stress to cells, which have both been linked to Alzheimer's disease."
https://www.alzheimers.org.uk/about-dementia/managing-the-ri...
[1] https://www.heart.org/en/news/2021/07/06/smoking-harms-the-b...
The study seems to go against everything else I've seen which suggests that as people are living longer, the incidence are increasing, not decreasing. However, my understanding is that as we get better at curing cancers, reducing heart-disease, and generally increasing life-span, the longer a person lives, the more likely they are to get dementia.
[1]https://www.who.int/news-room/fact-sheets/detail/dementia [2]https://www.abs.gov.au/media-centre/media-releases/australia...
Unclear. The cohort most exposed to atmospheric lead was born between 1951 and 1980 [1]. This study only measures those born before 1948.
(To the extent the study supports a hypothesis, it's the null. Given atmospheric lead increased from 1890 onwards, until about the 1980s [2], if lead were the culprit we'd expect to see more dementia among the study's younger generations. Not less.)
[1] https://www.pnas.org/doi/full/10.1073/pnas.2118631119
[2] https://www.sciencedirect.com/science/article/abs/pii/S10406...
That being said, there's some remarkable correlations with bans on leaded gasoline.
He's been referred to as a "one man environmental disaster".