Younger generations less likely to have dementia, study suggests | Hacker News Reader

Younger generations less likely to have dementia, study suggests

theguardian.com

149 pointsrobaato149 comments

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.

> 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.

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.

> 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.)

> 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?

And while smoking has plummeted, nicotine usage is resurgent

As is smoking of other things

Of course nicotine addiction is one problem and putting ash in your lungs is another

Interestingly, there's reasonably good basis to suspect nicotine (though not smoking) can reduce rates of neurodegenerative disease like Alzheimer's and Parkinson's.

You are correct but you really need to provide a source when making this claim because it sounds so unbelievable:

https://www.healthline.com/health/alzheimers-dementia/nicoti...

(Not calling healthline a source, but it has links to publications for those interested).

It's important to note, of course, that smoking increases the risk of pretty much every bad health related thing that can happen to you, including dementia. However, using nicotine without smoking might have benefits due to its effects on acetylcholine receptors.

I would think pesticides in the 1890’s through 1930’s were not as dangerous as what came later.

Is that a poor assumption?

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.

https://en.wikipedia.org/wiki/Lead_hydrogen_arsenate?wprov=s...

My great-grandma is the only one in my family who died of cancer and she used to apply farm chemicals by hand

this is a thousand percent due to lead

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.

The older generation would have been consuming lead arsenic in the form of pesticides at higher rates than the younger generation.

IDK if there's a way to measure who got the most poison though.

I expect the two world wars & a Great Depression might have more to do with it than pesticides or leaded gasoline.

Smoking reduces the risk of dementia because you die first.

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?

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.

> 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.

Could they prove this, as well?

> 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

A lot of healthy males were not away at war, because staying and performing their job was important.

>Pesticides don't explain why those born in the former have less dementia than those born between 1939 and 1943

If only there was something big in the world happening from 1939 to 1945 ...

I dread to think what diseases the even 'younger generations' are going to get with all the microplastics in just about everything we eat, drink, and in some cases breathe.

Hell, when chewing gum is made of plastic, I don't think we need to worry about the microplastics in the food.

Why is that? Chewing gum is perfectly avoidable, ingesting food not so much.

Microplastics have recently become understood, but humans have lived with a lot of plastic for many, many decades now.

Wouldn't it most likely be nothing significant? We love plastic because it's so inert..

The problem with microplastics is that it's forever breaking down in very small amount of very reactive substances.

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.

The author made it very clear that she believed the problem was indiscriminate use of, and overuse of pesticides. She explained this at the end.

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?

My personal experience is your immune system is sharp on both sides. You hope whatever antibodies and immune response gets triggered doesn't cross react with self.

I have some friends that had Hashimoto's disease. Type 1 diabetes. Friends with lupus. 4-5 friends that had Guillain-Barre syndrome. My mom died of ITP. I have sarcoidosis. I have friends who for unexplained reasons are 'unwell'

ITP is an interesting one. The antibodies target an enzyme that's needed to keep your blood platelets from binding together in your blood. Thus the idea that you can have autoimmune syndromes that can mess with thousands of different enzymes and proteins. Or stimulate inappropriately. Seriously why not.

I can totally believe that infection with childhood diseases of yore could lead to dementia later in life.

As an anecdote, there seems to be increasing evidence of correlation between infections by virii of the herpes family and dementia.

How much you want to bet that Alzheimer's is like ITP?

I’ve been thinking maybe part of it is just how much more we use our brains these days without even noticing. Like, my grandparents had tough lives, sure, but things were pretty routine. They did the same tasks every day, didn’t have to constantly adapt or juggle ten different things at once. Now? We’re switching between apps, replying to emails, figuring out random tech stuff, managing a million small decisions all day long. Even doing something simple like buying groceries online comes with dozens of tiny choices. So maybe it’s not just about avoiding brain damage maybe we’re giving our brains a constant workout without realizing it. Not saying we’re geniuses, but just being mentally active every day might help keep things sharp over time.

your grandparents probably read for entertainment instead of tiktok

your grandparents were more physically active - brain and body are connected

your grandparents didn't eat ultra processed food because it hadn't been invented yet...once again, brain and body are connected

> your grandparents probably read for entertainment instead of tiktok

It's not trivial to say that our grandparents read more than us. Paper books, newspapers and magazines are less common but we have ebooks, substacks and online newspapers now.

> your grandparents were more physically active

Perhaps at work, but my access to exercise during leisure time is much greater.

> your grandparents didn't eat ultra processed food because it hadn't been invented yet

I don't have hard data on this, but I think it's fair to say their generation's overall exposure to toxins was much greater. DEET, smoking, leaded petrol, asbestos and coal power stations seem much worse than the occasional McFlurry.

>I don't have hard data on this, but I think it's fair to say their generation's overall exposure to toxins was much greater. DEET, smoking, leaded petrol, asbestos and coal power stations seem much worse than the occasional McFlurry.

Don't forget petro wast such as plastic. It is amazing that we are still a live.

> I don't have hard data on this, but I think it's fair to say their generation's overall exposure to toxins was much greater.

Just another day my parents were annoyed remembering that the "big, bad government" banned a popular medicine from my grandfather's time. One that people used on cuts all the time.

Turns out the medicine was lead acetate.

Are you sure it wasn't Mercurochrome you're thinking of? It's a mercury compound that was very commonly used to disinfect cuts and scrapes.

It was prepared from mercuric acetate and sodium dibromofluorescein.

Goulard's extract, containing lead subacetate, was used on cuts too, but from what I can tell it wasn't nearly as widespread/famous as Mercurochrome.

No. Mercury acetate was banned way later (what makes sense because it wasn't the main ingredient on the finished product), that's probably why you know about it.

It was lead acetate, dissolved on water and a small bit of ethanol.

> your grandparents probably read for entertainment instead of tiktok

We still do? Tiktok/shorts are that on the toilet/in bed activity. I still spend I'd guess on average at least 8 hours a day reading. Not necessarily books but diverse articles, game guides, work stuff..

> your grandparents were more physically active - brain and body are connected

More physically active but not more active in skillful tasks. I've seen correlation between less/later dementia and things like playing musical instruments but I've not heard of construction workers being dementia resistant.

> your grandparents didn't eat ultra processed food because it hadn't been invented yet...once again, brain and body are connected

Mine ate whatever was available. Many unleavened flour+water flatbreads baked on the woodfire oven used for heating, rice and lots of lye in winter. Lots of fruits and veggies when available.

Now we mostly eat much better. You have every single fruit/vegetable/meat available 365 days a week, very clean food.. Only gotta stop yourself from overindulging.

We also have better medicine, better cleaning products, better understanding of what's toxic and bans based on that..

>your grandparents probably read for entertainment instead of tiktok

This is a reach... Have you met old people? They vegetate in front of the TV channel surfing- their version of TikTok- never questioning the content or researching topics further on their own. And after 40 years of this activity still don't know how to operate the remote.

>your grandparents probably read for entertainment instead of tiktok

I'm not actually sure my grandparents were able to read, let alone for entertainment. Not in the US fwiw.

>your grandparents probably read for entertainment instead of tiktok

I strongly disagree. Reading books as activity, maybe. It depends on the person too. But reading itself? In this time and age, we are constantly reading, either in your phone ( even most tiktok videos these days have subs for everything ), browsing the web is a constant reading activity, work/email/essays/whatsapp/telegram, completely outweights the amount of text we read/write now comparing it with our older generation.

That could easily go the other direction. We’re overloading our brains so much that eventually they’ll just shutdown.

It could but you need a body of evidence for it, plus credible pathways to explain it. So far the greater weight seems to be behind "use it or lose it".

Bilingualism has been shown in studies to delay cognitive decay [1]. Nearly everyone outside of US/UK in the younger generation speaks at least two languages pretty well, while the older ones often don't.

[1] https://pmc.ncbi.nlm.nih.gov/articles/PMC4052164/

> Nearly everyone outside of US/UK in the younger generation speaks at least two languages pretty well, while the older ones often don't.

Interestingly, the opposite seems to have been happening in Malaysia. The older generation tend to be able to speak a ton of languages (Malay, English, Chinese, Cantonese, Hokkien, maybe more), my generation has mostly settled on just English. I have gone out of my way to learn Japanese but even then, I can only understand 4 languages and speak 2 vs the 5 languages my parents/grandparents are essentially native speakers of.

If you force yourself to communicate in certain language, you more or less will be able to communicate with it sooner or later.

(Provided that you have basic understanding to the language)

Lmao doom scrolling and choice paralysis is not using you brain

I swear I'm not trying to throw a ton of shade here, but it's amusing this is the current top comment when the article says they studied people age 70 and older, which of course they did because those are the people likely enough to have dementia at all that you can do a meaningful comparison.

> “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,” said Lenzen, adding similar trends were seen in Europe and England, although less pronounced in the latter.

I don't think people born between 1939 and 1943 are less likely to have dementia because of all of the cognitive activity that went into replying to e-mails and choosing groceries online back in the 1970s.

Definitely feels like that effect is more likely to be explained by the Great Depression and World War II than anything else.

https://www.michiganmedicine.org/health-lab/sleep-apnea-cont...

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.

Dude, global estimate for OSA is in the range of 1 billion, its a global pandemic

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.

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.

I read that as saying that 3% CPAP usage couldn’t explain a 10% drop in dementia.

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)

I wonder if sleep apnea diagnoses will decrease with the increasing use of GLP-1s?

Zepbound is FDA-approved for OSA.

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.

Isn't sleep apnea associated with obesity, which undoubtedly has been increasing?

yes, but in one case we're talking about OSA causing dementia and in the other we're talking about obesity causing OSA

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.

GLP-1 drugs mean that peek obesity is already passed.

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.

[1] https://www.sciencedirect.com/science/article/abs/pii/S13899...

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

I have OSA and I haven't taken GLP-1 agonists but I've taken the road they put a person on. 50 pounds ago I was averaging around 15 apnic/hypopnic events per hour, now it's less than 10. My doctor told me that I may as well keep using my CPAP because it seems to help and it's already paid for but that if these were the results of my initial sleep study he wouldn't have prescribed one to me.

Slightly off-topic, but as someone in the field, what is your opinion of the apnea-detecting functionality of smart watches?

I'm in the field, I built the software in your cpap machine and home sleep study that we use to test and treat them. It comes down to microarousals, which is where you wake up just enough to disrupt the sleep cycle without actually becoming consciously aware. A smart watch can detect that, and it can also measure o2 saturation in your blood. To my mind that means that a smart watch can determine whether your sleep is interrupted and by how much, and even gather some evidence that apnea could be among potential causes (there are other ways to have low o2 saturation) but I don't think it can actually diagnose.

When I did my sleep study they monitored my o2 saturation. it's true that there's no ongoing monitoring during treatment though.

I didn't mean to imply they don't monitor o2 in studies, but the metrics of how apnea is diagnosed relies heavily on hypopnea independent of oxygen desaturation.

Respectfully... how do you work in the field, while being so wrong?

Oxygen desaturation correlates with long-term metabolic outcomes, but correlates very poorly to day-to-day symptoms.

The actual primary cause of symptoms in SDB is microarousals resulting from increased respiratory effort, and sleep studies using 3%-or-arousal criteria report MUCH higher OSA rates than the commonly used hypoxia+reduction in flow criteria, while also having a much higher correlation with symptoms(>60% vs ~17% for AHI), and the problem is not over, but under- diagnosis since people with relatively few apneas(e.g. UARS patients) are rarely diagnosed correctly.

Also, (optimally) healthy people DO breathe 100% of the time during sleep- breathing during sleep is controlled by a different system while awake, and is extremely regular during NREM sleep, with REM merely introducing noise to breath amplitude. Any and all pauses in breathing are caused by sleep disruption.

The only reason why it seems like apnea-based criteria are oversensitive is because obese, older men often DON'T wake up from airway collapse and may be fine at 5, 10, or even 15 AHI. For everyone else, it's possible to have debilitating symptoms at 4 because the actual Respiratory Disturbance Index is 20+.

Goddammit man. People like you are why so many go their entire lives unable to find treatment. If you're working in the field, educate yourself about it. Ugh.

This, precisely. An apneic event is defined as 10 seconds of pause in your breathing (https://www.sleepfoundation.org/sleep-apnea/ahi). Go ahead and hold your breath for a slow count of 10 (set a timer or do the mississippis or alligators or locomotives or whatever other 4 syllable phrase you need to do in order to make it a real, honest 10 seconds. it's long enough to be noticeably uncomfortable). You don't casually do that during the day. Sleep apnea is defined as you doing that 10-15 times per hour, and your sleep study also measures microarousals to correlate (source: I built the damn things for a living a few years back). Also they do monitor o2 sat in children at least, cyanosis is one of the ways they diagnose apnea in children.

Way too many professionals in the field thinking that they're the first person to think about something when literally millions of people think about this same thing all day every day.

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?

> 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.

[1] https://karger.com/ned/article-pdf/56/1/4/3752570/000520966....

I think being around explosions actually IS linked to Alzheimer's. It wouldn't surprise me to find a link to dementia as well.

But generally, bullets, disease, and malnutrition don't cause the same sort of brain trauma.

https://newsroom.uw.edu/news-releases/blast-related-concussi...

60 Minutes recently ran a segment on the cumulative damage of relatively small explosions (such as rifle shots) can lead to brain injury and dementia, even with hearing protection.

I know i gave you a little crap vis a vis the toyota stuck accelrator thing in another thread, but i quoted you about this stat twice, yesterday. I rarely pay attention to usernames when replying, and you have a breadth of experience that doesn't immediately identify who's "speaking."

how many books have you written ;-)

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.)

You had me wondering if wind-playing itself has unfortunate cognitive effects. (This seems just barely plausible, since you spend a lot of time breathing funny if you play a wind instrument.)

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."

Also being bilingual delays alzheimers by 7 years, so there must be something to dementia also.

4.7 years. Also, no evidence that it reduces the risk of getting it, the benefit is purely delayed onset. Still, I'd take an extra 5 years of working brain, if only I could learn a second language (does Python count?).

https://pmc.ncbi.nlm.nih.gov/articles/PMC7089902/

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).

[1] https://www.uth.edu/news/story/several-vaccines-associated-w...

That’s super interesting! From the first line I thought this comment was going to go the other way, lol…

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.

> 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.

[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/

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.

[1] https://www.health.harvard.edu/blog/can-a-routine-vaccine-pr...

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.

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.

> seeing varying rates of dementia based on this characteristic alone would be very unsurprising

Sure. That's why the antibody cross-reactivity is intriguing.

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.

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?

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.

Sometimes. Not reliably. I've seen studies correlating antibiotic therapy with reduced dementia rates in the next 5 or 10 years or something, but you can just as well wipe your gut microbiome and open it up to opportunistic pathogens.

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.

>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).

Excuse me?

The vast majority of millennials did not receive the chicken pox vaccine as it was not FDA approved until 1995. The youngest millennials were born in 1996. The oldest millennials were already in high school by 1995.

I guess I could be wrong here - I know that myself and several other friends got it as kids once it was released. It was given to us later than many of our other vaccines.

>I guess I could be wrong here

The only people in the US who have received an immunization for chicken pox were those who were NOT exposed to the chicken pox virus prior to 1995 (the first year it was available).

Before immunizations almost everyone got chicken pox in the first few years of life.

Thus the majority of people born between 1981 and 1996 were exposed to the chicken pox virus before 1995 and weren't eligible for immunization.

I was born in the early 80s and got chicken pox in 1993. It was considered very late at the time, everyone was like "wow, how have you not had chicken pox before?"

There was an interesting article along those lines: The brain microbiome: could understanding it help prevent dementia? https://www.theguardian.com/lifeandstyle/2024/dec/01/the-bra...

Would be a crazy plot twist if social media and doomscrolling were protective against dementia

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)

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.

This is the most egregious rationalization of the Capcha dystopia I've ever seen.

Captcha… the whole time it was the true bicycle for the mind

Please select the squares that contain the bicycle for the mind.

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.

somehow I suspect it's going to be the opposite.

How is scrolling through videos on tiktok better than flipping through channels on a TV?

Not a chance that idly scrolling through videos is better than trying to figure out why a PR is breaking the compiler.

Can't tell from ur comment, but for the people that didn't read the article this is comparing people born in ~1890 to those born in ~1940

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

How do you get dementia from smoking?

"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."

https://www.alzheimers.org.uk/about-dementia/managing-the-ri...

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.

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.

[1] https://www.heart.org/en/news/2021/07/06/smoking-harms-the-b...

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.

In my family it’s the other way around. It’s very worrisome that both my father and grandfather had dementia.

Same here. It's like a specter always one step behind me.

“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.”

https://www.alzheimers.org.uk/blog/why-dementia-different-wo...

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.

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.

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.

I hadn't seen that. I'll take a closer look. Thanks

Do you have anything that shows the link to sleep disorders and menopause? And if you happen to know, does that apply to artificial menopause, where the organs have been removed, and then you go through menopause directly afterward?

> sleep loss during child-rearing and menopause

The prevalence of obstructive sleep apnea is much larger in men than in women. If sleep loss were the only factor we probably would see greater dementia incidence in men, due to long-term chronic sleep loss from OSA.

How was smoking identified as the cause’s of dementia in the individual you mention?

I've not seen air pollution mentioned yet. We've passed peak air pollution and generally research keeps revealing it to be worse than we thought for a variety of diseases you might not immediately link it to, like heart disease and stroke.

Some of the research on gas stove pollution noticed an uptick in problems for women and linked it to them being closest to poorly operating kitchen burners (and burning food particles themselves might be a factor).

https://ourworldindata.org/data-insights/the-world-has-proba...

Glancing at the data for the US this seems to go the opposite direction, ramping to a peak in the 60-70s when I'd assume most damage in early years and/or working age.

Though perhaps local and widespread air pollution are not following the same trajectory.

Not just air pollution at large but specifically we are practically sunsetting diesel engines in most developed urban centres.

I can't find a quote but one trivia bit from 'diesel gate' is that the execs were aware of the neurotoxicity of NO2 and other substances that were found in higher concentration in diesel exhaust.

one got it from smoking, and the other 2 got it from not smoking

Study: https://jamanetwork.com/journals/jamanetworkopen/fullarticle...

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.

[1]https://www.who.int/news-room/fact-sheets/detail/dementia [2]https://www.abs.gov.au/media-centre/media-releases/australia...

You can actually have dementia without the symptoms if your interconnect is strong.

Like knowing multiple languages/ multiple words for one thing.

I read today that people who are now 50-75 years old were at the peak of exposure to leaded gasoline fumes.

It's pretty well established that greater lead exposure leads to increased risk of cognitive decline.

I'm not saying that's all of it, but it seems like it could be as much of a factor as anything.

It will be a major oops moment when we will find out that dementia is caused by some weird kind of bacterial or prion infection. And the whole moral explanation of it ("go read your damn books and talk to smart people or you will get Alzheimers!") will turn out to be same bullshit as moralistic obesity explanations ("just lazy and can't control yourself!") recently turned out to be.

One big thing that changed in these decades is cleanliness simply due to better cleaning chemicals. Which certainly caused a reduction of infections of all kinds.

> turn out to be same bullshit as moralistic obesity explanations ("just lazy and can't control yourself!") recently turned out to be.

Any reading on that?

Have you heard of Ozempic?

Ozempic takes your willpower out of the equation so I'd say it puts a lot of people into the low self control category...

I know people who've been obese all their lives and lost massive amount of weight once they were properly explained stuff like calories, glycemic index, excercise... I wish I was joking but some people out there are not even aware that food is supposed to be fuel for the body, not just something that you take when you're bored or because it tastes good and make you feel happy.

Reminds me of one funny probably-not-taken-very-seriously historian theory about Alzheimer's - that air pollution was responsible for its existence and the few natural sources were rare enough that there weren't any 'got Alzheimer's by spending too much time by an erupting volcano' cases. The main reason being the lack of pre-industrial accounts of anybody being old enough to show memory issues.

It isn't strong proof by any other means. The bias of the accounts excluding it would sort of be like concluding that acne wasn't an issue because painted portraits of teens excluded them. I don't know if this theory is true but it is certainly an interesting one.

Is it the shingles vaccine? Studies suggest that one vaccine reduces the incidence of dementia by ~20%, for reasons still unknown. https://med.stanford.edu/news/all-news/2025/03/shingles-vacc...

Many toxins were eliminated from everyday products and environments.

Lead?

Personally, I think it's some other pollutant.

That being said, there's some remarkable correlations with bans on leaded gasoline.

The man who invented leaded gasoline - Thomas Midgley Jr. - also invented CFCs.

He's been referred to as a "one man environmental disaster".

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.

> Lead?

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...

Cars only fully replaced horses after WW2, so they were the first universally exposed generation, if anything.

Will they abstain from taking statins?

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