- Lead gasoline stopped being sold(this is also theorized why crime dropped alot from the 90's)
- Pollution being down across the board due to better EPA standards and electric vehicles.
- Increased internet access and more games/puzzles with smart phones to stimulate the mind.
- Lead paint being taken very seriously as being detrimental to health. having specialized crews dealing with removing it, also asbestos being removed from society in the same way.
IQ is a protective factor for some (but not all) forms of dementia [1]. Could the Flynn effect, by raising IQs, reduce the risk of some forms of dementia?
Immigration is another factor that could be increasing IQs, which in turn may decrease the incidence of dementia. Many countries have immigration programs that give preference to skilled professionals, who are likely to have above average IQs. Another immigration route which favours above average IQ is education-based immigration – come for university, stay after graduation.
IIRC the Flynn effect has been in reverse since the mid 90's. Here's a quote from Wikipedia:
"Research suggests that there is an ongoing reversed Flynn effect, i.e. a decline in IQ scores, in Norway, Denmark, Australia, Britain, the Netherlands, Sweden, Finland, France and German-speaking countries, a development which appears to have started in the 1990s".
In my country, Australia, we saw zero improvement on the Colored Porgressive Matrices from 1975-2003, and a decline since then.
It'd be interesting to see if reversal of the Flynn effect is correlated with massive unskilled immigration (esp from third world countries), which has accelerated in many European countries.
If we examine countries with extremely strict immigration policies that favor the skilled (e.g. Singapore), will we see IQs going up?
The birth rate differences between high IQ and low IQ sections of the population have been suggested as the primary driver of this. The fact that it's been suggested at all is amazing due to the western world's strong avoidance of any topic that resembles an argument for eugenics.
Is that really a thing? I live in Australia and I'm really careful about who I have sex with mainly due to not wanting to catch HSV-2. I'm an early 30's man and I turn down more potential sexual partners than not. Condom use prevents most STD's + unwanted pregnancy with a high degree of success but not HSV.
I would say “probably not”. First, as anecdata, I was a plaintiff’s attorney for asbestosis/mesothelioma sufferers and every client I had was whip-smart. Other than being older and having concomitant capacities they were very sharp. More tellingly, we (attorneys) scoured medical literature for any and all possible claims against asbestos manufacturers, and I never once saw a claim related to diminished intellectual capacity. If there was even a skosh of evidence somewhere in that regard some attorney would have found it and figured out how to add it to a lawsuit.
I would argue the decrease in dementia is way to large to be explained by asbestos. Even when it was commonly used, the number of people exposed was pretty low. You'd either have to be mining the stuff or working in an industry that commonly used it.
Your average office worker isn't going to get exposed to asbestos except for rare situations where asbestos material is being actively manipulated.
Asbestos fibers enters the capillaries in the lungs and over 20 years work their way into the sack holding the capillaries to then scab and become tumors. During that 10-20 years, shallow coughing and shortness of breath could lower blood oxygen levels that can’t be good for cognition.
Idle suspicion is the elimination of childhood disease via vaccination may have played a role. For instance my generation born in the early 1960's the was first to be vaccinated against measles. And measles can cause neurological problems decades after people recover. There is also a trend to suspect that Alzheimer's is caused by inflammation.
Can you provide sources for the first point? Who theorised it? I've never heard of the use of lead gasoline being linked to crime ... Interesting to learn more.
Here are some better explanations for the drop in crime in the 90s:
Innovative policing strategies,
Increased reliance on prisons,
Changes in crack/other drug markets,
Aging of the population,
Tougher gun control laws,
Strong economy,
Increased number of police,
http://pricetheory.uchicago.edu/levitt/Papers/LevittUndersta...
Also, at least one of the leading papers propounding the lead hypothesis also tried to account for those confounders within the U.S. The onset of harsher policing and criminal punishment varied between states while the removal of environmental lead was more uniform, and the resulting analysis supported the lead hypothesis. Conversely, where the time of lead removal varied while policy reforms didn't vary, the same lead relationship was still found. Indeed, even outside the lead context there's a ton of research that suggests the increase and subsequent decrease of violent crime preceded policy changes. That overwhelming evidence is why there was bipartisan support at the Federal level for criminal justice reform. And that research is why progressives in California are adamant that reductions in criminal penalties aren't responsible for the huge increase in property crime in the state, even though most of that research was concerned with violent crime (and indeed violent crime hasn't substantially increased).
https://stevenpinker.com/files/pinker/files/pinker_comments_... Steven pinker makes some good points in this short essay why there should be more skepticism towards this hypothesis:
“ Also, the parallelism in curves for lead and time-shifted crime seem too good to be true, since the lead hypothesis assumes that the effects of lead exposure are greatest in childhood. But 23 years after the first lower-lead cohort, only a small fraction of the crime-prone cohort should be lead-free; there are still all those lead-laden young adults who have many years of crime ahead of them. Only gradually should the crime-prone demographic sector be increasingly populated by lead-free kids. The time-shifted curve for crime should be an attenuated, smeared version of the curve for lead, not a perfect copy of it. Also, the effects of age on crime are not sharply peaked, with a spike around the 23rd birthday, and a sharp falloff—it’s a very gentle bulge spread out over the 15-30 age range. So you would not expect such a perfect time-shifted overlap as you might, for example, for first-grade reading performance, where the measurement is so restricted in time.”
I’m also not convinced on your point about crime in California. The police have essentially ceased prosecuting many of those petty crimes. It makes sense that they would go up with no deterrence.
Criticisms of the lead hypothesis are definitely noteworthy. Evidence for the lead hypothesis does seem too good to be true, and maybe is, especially as a single factor.
> I’m also not convinced on your point about crime in California. The police have essentially ceased prosecuting many of those petty crimes. It makes sense that they would go up with no deterrence.
Yes, of course. Progressives blame rising inequality for an increase in property crimes, but it seems quite obvious the immediate cause is a lack of prosecution as I'm fairly sure not many people are supporting families by ripping off stores and smashing car windows. And while municipalities could and should prosecute, both the police and district attorney offices have the habit of only vigorously pursuing felonies--increasingly only violent felonies.
Better? There's no reason to say so. The author even says:
> Reyes (2002) offers an additional intriguing explanation for the decline in crime: the reduction in
levels of lead in the blood due to the elimination of leaded gasoline and lead-based paints. Because of
the highly speculative nature of the Reyes conjecture at the present time, I do not discuss this hypothesis at greater length, although it is clearly an area worthy of continued future
The lead hypothesis offers no explanation for the huge surge in crime in the late 60s and 70s. However the fact is that criminal justice system was handicap during that time. Crime just wasn’t prosecuted or punished in that period.
I would also say that they are far more likely. correlation is not causation. Lead exposure and crime are very widely separated variables.
^^ This is the original paper and the full pdf is available. I recommend a brief perusal before posting your "guesses". It's not very long and has pretty graphs.
Although in fairness, the paper mostly just speculates itself as to the underlying cause--mostly better control of high cholesterol and blood pressure, presumably primarily through drugs.
Think of it this way, not only was lead gasoline banned, but over the last 30 years we have moved manufacturing jobs to Asia (which has not seen the decline in dementia that the west has).
Manufacturing exposes workers and the surrounding area to all kinds of dusts, chemicals, etc.
My mom tells stories about pesticide trucks driving down the street, spraying entire neighborhoods, when she was a kid. Says it happened pretty often. Kids would chase them, playing in the "clouds". Talk about yikes.
I do wonder what we interact with regularly that future people would have to be paid very well to even be in the same room with, and will think we were nuts for ever thinking was OK. I'm guessing "basically anything plastic, especially if contact with food" is a likely candidate. Fire retardant chemicals in construction materials and furniture, probably.
>I do wonder what we interact with regularly that future people would have to be paid very well to even be in the same room with, and will think we were nuts for ever thinking was OK.
I am betting on combustion engines. It is ridiculous that we have hundreds of millions of those on our streets, releasing the fumes straight into the air where we live our whole lives.
Don't forget rubber tires grinding against asphalt at high speed. Or brake pad dust. We're already at the point we know it's bad to spend much time near highways (say, living within a few hundred feet of them) but haven't, as a culture, really decided to do anything about it yet. Probably because we're too all-in on 55+ MPH roads, so far as infrastructure, so the cost to fix our mistake would be too high.
Staying at a rental that is next to a residential street, the city is very clean and air is great. The street has somewhat alot of traffic and I noticed that the table outside we eat on gets dirty very quickly. Like in one day a wipe on it is black and filthy from the street which is behind a hedge 20ft away.
The balcony of the flat where I live at is unusable because of the major street next to it. There's this same greasy dust everywhere. My guess is that it is soot, covered with unburnt hydrocarbons, from car or oil heating exhaust. It's really disgusting. I have resigned long ago to not let plants intended for consumption grow there...
It's ridiculous now, yes; but don't forget that tech progress is cumulative. We likely needed those "fumes" so something better could come along and stand on its shoulders.
It's pretty exciting to be living during a transition period to cleaner energy. Just as exciting is signs of tangible evidence that this movement is indeed better for our longevity and quality of life. I'm hopeful we will keep progressing.
Oil-based cars and trucks kill people in cities and exacerbate many illnesses like asthma. When they are gone people will wonder why they were ever allowed.
>> When they are gone people will wonder why they were ever allowed.
The engine tech may go away. The vehicles wont. CO2 doesn't cause asthma. Most particulates, at least from non-diesel vehicles, comes from things other than the enigne. Brake pads, tires, even the road surface itself. They all wear down, turning into dust, and get inhaled into our lungs. Electrification won't change that.
One interesting line of research is carbon fiber fires, and increasing problem as many high-end EVs are using CF to reduce weight. One CF vehicle, on fire after an accident, will release a massive amount of very fine particulates that could drift on the wind for many miles.
I'm increasingly convinced that allowing widespread use of automobiles on public roads will be regarded as one of the biggest societal-engineering blunders of all time. Between the health effects (of the cars and roads themselves, plus the secondary effects on physical activity) and the adjustments to city layouts plus extra costs eating most or all of the time-savings anyway, it's hard to see a clear upside. Granted much of that would have been difficult to discern when early decisions on the topic were being made, but that doesn't make it any less an error in its effects.
Look at what city slums were like before widespread motorized transporation. The ability to live in a different area than the coal plant where you worked was a massive improvement to health. Even today, with COVID, the ability to live in suburbs vs high-density inner city biuldings is a benifit.
Then there are the knock-on social mobility benifits such as being able to switch jobs without having to move your family. Or, at a lower level, not having to rent your house/appartment/shack from your employer. Many people see cars as evil today, but realize that today is not yesturday.
I highly recommend researching the Dutch street design. By explicitly avoiding freeways and encouraging biking, they save so much time (no traffic) and money (think long term health benefits of cycling, no pollution, cheaper infrastructure, lower reliance on fossil fuels, fewer accidents, more visits to local businesses) it's insane the rest of the world isn't copying them ASAP.
Vastly enhanced point-to-point mobility seems like a pretty clear upside to me. Absent cars, public transportation would doubtless be better. But people would have far less flexibility in where they lived, where they went for recreation, and in many other things.
The trouble is that, 1) cars are much more expensive, when you tally it all up, than walking and bicycles, so one must count against them the time it takes to pay for them (and if one is very exactly accounting, one might also place some portion of time spent on dedicated, otherwise-unproductive aerobic exercise against cars' account), and 2) once a city's adjusted its girth to account for cars, the points most often factoring into ones point-to-point mobility are much farther apart than they'd have been without adjustments made due to widespread use of cars. Notably this doesn't include only people choosing to move farther apart, but everything being pushed apart by large setbacks from unpleasant roads, enormous highway interchanges, and gigantic parking lots. The car's value, even absent its effects on health and the environment, seems unavoidably to dwindle to very little if too many of them are in use.
Sparing use? Buses, perhaps, emergency vehicles, and possibly delivery trucks? Probably a solid, significant improvement. Individual automobile use on public streets in and around urban areas, and all the adjustments necessary for that to happen or consequent of car-influenced growth patterns? Way, way murkier than one might initially expect, but now very expensive and difficult to reverse regardless, so we're stuck spending a lot more to travel farther and save, if we buy cheap cars and have a high paying job, a little time.
>>>cars are much more expensive, when you tally it all up, than walking and bicycles
Walking and bicycles provide no protection from the elements. Depending on where you live and your occupation, the ability to travel in climate-controlled conditions and arrive with your work clothes unsoiled can be a massive utility benefit.
>>once a city's adjusted its girth to account for cars, the points most often factoring into ones point-to-point mobility are much farther apart than they'd have been without adjustments made due to widespread use of cars. Notably this doesn't include only people choosing to move farther apart, but everything being pushed apart by large setbacks from unpleasant roads
I'd argue that the land area dedicated to roads is a small portion of what forces businesses apart, and that low-density construction and inherently smaller buildings is the major contributing factor. There's only so many shops you can fit into 3-story buildings with narrow footpath-like streets between them. Hanoi is a good example of that. 48QWJ8705424314 (MGRS, paste into Google Maps)
Compare that against the alternative - horses. Horses were a huge sanitary problem - manure and dead horses. Horses also simply killed a lot of people, as they are big and strong and not always controllable.
Apparently some places, like England and New York City, kept very good records on horse and other traffic accidents. Here's a paper that purports to show that horses were dangerous and even more dangerous than cars: The Dangers of Automobile Travel: A Reconsideration, https://www.jstor.org/stable/27739679
But I quickly read through the entire thing (JSTOR still has free access: cool!) and AFAICT automobiles were far more dangerous than horses, both in absolute fatalities and presumably even more so adjusting for the number of horses and cars per capita. Toward the end the author tacks on train and streetcar deaths just to make automobile deaths look better. Indeed, it's not until the very end where the author isn't constantly drawing conclusions and providing anecdotes that seemingly contradict his own hard data. Only on a per mile basis, and then only a few decades into the age of the automobile (i.e. after traffic controls become common and pedestrians become persona non grata on the street), are automobiles indisputably safer.
Considering the utter lack of almost all traffic controls prior to the automobile and the way that pedestrians intermixed with horses, the figures are actually astonishing. More astonishing when you look at train and streetcar deaths, which were apparently incredibly lethal. I'm glad I found that paper because almost all other sources I found--which completely lacked any hard evidence--claimed horses were far more dangerous. (So does this one, though the data suggests otherwise.)
I talked to a 60 year old cowboy about the dangers of horses and asked him how many times he was stepped on.
Twice. From 7yo to his early sixties. Given that horses are active participants in traffic and they will go out of their way to not step on you, they would seem to be orders of magnitude safer compared to cars.
I've been stepped on by a horse and my total time dealing with horses is probably less than an hour.
Besides, I'd expect a professional cowboy to know how to protect himself from horses, just like a professional driver is going to have fewer car accidents.
We're all "professional pedestrians" too (on some countries at least even trained as such from early age). You probably weren't prepared appropriately for your encounter with horses.
Absolutely agreed. Tons of knee jerks against this, but I'm almost positive future society will conclude this, unless it's too screwed up itself to spend much effort judging the past.
I feel like vehicles personal vehicles will be considered a societal-engineering blunder when we have personal teleportation available as an alternative.
The widespread existence of them has made everything grow farther apart, due to their needing lots and lots of space and people not wanting to be close to where they're traveling, and they're quite expensive, and for most people it takes time to make money. Their value as a time-saving device in a world that has adjusted for their presence is less overwhelmingly-positive than one might think.
This might be a controversial opinion but I think that's a big plus. Look at old European cities with tiny streets that were mostly designed in times before carriages & cars; vs modern American cities (e.g. upper Manhattan) with large streets, a lot of driving and walking space, etc. Sure, the European model might be more romantic but the US one is definitely more functional (density isn't an issue either; London is much less dense than Manhattan).
I highly recommend researching the Dutch street design. By explicitly avoiding freeways and encouraging biking, they save so much time (no traffic) and money (think long term health benefits, cheaper infrastructure, lower reliance on fossil fuels, fewer accidents, more visits to local businesses) it's insane the rest of the world isn't copying them ASAP.
https://www.youtube.com/watch?v=XuBdf9jYj7o
Almost every automatic nowadays gives you a couple of gears to play with. I always downshift on curves or when braking to a stop. I also drive a hybrid and downshifting guarantees regenerative braking whereas with the pedal it’s easy to over do it and engage the pads.
Thanks, I didn't know engines specifically cut down the fuel supply nowadays when engine braking. I'm not sure charging the car battery used for lights etc counts for much though!
I do think this is significantly different in ICE cars from regenerative braking in EV cars which actually stores the energy and can use it to drive the engine later. This still comes out ahead against ICE cars which don't burn much energy while going downhill.
There's a lot of electricity-driven stuff in ICE cars these days. For example in my car AC is running off car battery, not directly using the engine. When driving in city, start-stop turns off engine at traffic light and AC keeps going.
Regenerative power for starter in frequent start-stop cycle must help a lot too.
Lights do add up too. I remember when a good decade ago day lights were made mandatory all around the year all day long. Very few cars had LED daylights so most people had to run dipped lights. Some people did backyard tests that lights add 0.5L/100km or so. Obviously now LEDs are much more efficient. On the other hand, infotainment system is ever bigger beast. But if regenerative braking power can take off the edge... Why not.
Anyway, I'm not saying that ICE is better than EV. Just saying that ICE can make use of regenerative power.
Exposure to pollution caused by cars and other vehicles is strongly correlated with asthma.[0] I'm glad you mention CO2, which does cause global warming, we might want to try to fix that too before it is too late?
Carbon Fibre is expensive and irrelevant, and fires from it even more so, unless you want to minimise the impact of oil based cars on health in cities. Most popular EVs don't use it.
Traffic is a major source of particulates (20-30%) [1] so reducing it would help a lot, in particular diesel cars and trucks, though yes some things like rubber from tyres would only be helped by traffic reduction, simply switching to EVs would help a lot.
Moving to walking, bikes and public transport for most journeys in cities is the sustainable answer I suspect we'll end up at, and from that future our reliance on individual polluting cars will seem insane. It would require a rethink of some city planning of course, but many people happily live without cars in Europe at the moment.
>>>When they are gone people will wonder why they were ever allowed.
Because they're FUN. https://youtu.be/-mqXXqB7SBQ
Just like eating red meat. It has consequences for you health, but bacon-wrapped filet mignon, in moderation, is worth the consequences.
I'm happy for you to make that sacrifice to your health, I'm not happy for you to impose the health consequences on your poorer neighbours (as happens driving a car in a city).
People are going to wonder why cars and trucks were allowed?
A core part of our transportation network that delivers nearly every product we purchase and moves people around so they can work and have a social life.
Cars do very few deliveries, and hard as it might be to imagine in a US city designed around cars, they're simply unnecessary in a dense city, in fact they negatively impact everyone else. Diesel trucks do not belong in cities IMO.
Yes, people are going to wonder why it was ok to kill others with pollution by driving through cities with combustion engines.
That was DDT. Occassional exposures like that aren't linked to anything horrible in humans. It was banned for its impacts on birds, specifically their eggs. (Google "silent Spring".)
> DDT is classified as "moderately toxic" by the US National Toxicology Program (NTP) and "moderately hazardous" by WHO
> studies document decreases in semen quality among men with high exposures (generally from indoor residual spraying)
> Indirect exposure of mothers through workers directly in contact with DDT is associated with an increase in spontaneous abortions
> studies found that DDT or DDE interfere with proper thyroid function in pregnancy and childhood
> Mothers with high levels of DDT circulating in their blood during pregnancy were found to be more likely to give birth to children who would go on to develop autism
Yeah, I don't know of any particular harm linked to it, it just seems like something we'd never let kids do these days just in case, since "apply magical chemical, it fixes everything and is entirely safe!" has a history of being wrong about the "entirely safe" part. These days I'd expect any plan that includes "we'll spray clouds of this in neighborhoods" to get shut down before it can even start, for that reason.
Except cholrine in pools. And soap. Soap has all sorts of chemicals in it. And perfume. The reality is that we soak ourselves in various chemicals every day. What if that truck was spaying hand sanitizer? It is the chemical that matters, not the method of distribution.
I think you're thinking I'm in the "ZOMG ban dihydrogen monoxide, it's a chemical!" crowd, and I'm not sure why you think that. Also, yes, I'm pretty sure you'd have a hard time convincing people to let you spray hand sanitizer all over their neighborhood, these days, even if they're OK with rubbing it on their hands.
Perfume/colognes popularity seems to wane around the same age group of people who grew up being ok being doused in pesticide. That age group is of course country dependent, but seems to track together
> It is the chemical that matters, not the method of distribution
Found the person that didn't see Batman Begins;
If you think dancing around in aerosol'ed hand sanitizer would be okay, you've clearly never gotten alcohol in your eye, nose, or dare I say throat.
Perfume is also a really interesting one, because some of us do sneeze every time we smell Abercrombie or do start anaphylaxis around flowers or other certain plants. Which comes right around to soap, which, yes, people are allergic to dyes and fragrances in, so we make pure and hypoallergenic.
Chlorine, in pools; We've made drastic progress on that one in society in the last 30 years; from barrels of chlorine when we didn't understand it, to carefully measuring it, to now we have salt reactors that continuously meter it.
I think the point was that we know it's safe (e.g. due to the skin barrier as you mentioned) and we're not likely to change our opinion about soap safety in a decade.
In other words, despite there being many cases of egregious mistakes in safety assumptions due to our bad understanding of science (and/or malice) in the past, we're tempted nowadays to err on the side of caution and probably overestimate the ratio of chemicals we use in our daily life that turned out to be bad, to the ones that we got right.
Sizeable parts of the populace nowadays associates the word chemical with unhealthy. Yet, they buy products that have the word "natural" on it, crafted by mixing and processing products of natural origin. But nature is full of chemicals. Mixing them and processing them, grinding them, heating them up, etc, is what chemical processing is about.
Does it have a sent? Then it is entering your lungs. This was a big deal a few years ago as sandlewood sents in many soaps were linked to hormonal changes in young males.
Scent can be created with as little a few ppm to ppb levels of substances in the air. Most of the typical substances that smell are in too low in concentration to do any harm.
Is classified as moderate toxic but in high acute doses can still kill a children.
Is bioaccumulative, in fatty tissues, and a probable human carcinogen. Acute exposures in girls are said to increase x5 the probability of developing breast cancer as adult.
I don't know if it's less frequent today or if cities are more discrete about it considering modern paranoia. Growing up in the 90s in Florida I remember the trucks driving by on occasion, usually around dusk. If they did it late at night I'd be asleep and would be less likely to notice, so I couldn't say with any certainty how frequently they sprayed.
Also, looking at those videos, the method seems to be different and less noticeable. I remember huge, dense fogs that would envelope the whole neighborhood. In the above videos the spray disappears almost instantly.
We still have mosquito killer smoke sprayed in India in rainy season. I found the similar smell & smoke if I dip a sufficiently heated metal piece in Kerosene.
Japan was the first country to introduce unleaded petrol/gasoline in 1972 and the first to ban leaded petrol in 1986 but, according to the article, they aren't seeing the decreases that Europe and North America are seeing. So that fact doesn't support your hypothesis even though I am sure there have been many other health benefits from the ban.
>>The trend may be related to higher rates of smoking, which makes dementia more likely, in those countries.
There are any number of not-good things in tobacco smoke. The modern reality that we no longer live in a costant haze of other poeple's smoke is probably a huge factor in overall rates for many diseases.
Smoke exposure of any kind seems to have adverse health consequences over the long run. The first thought that jumped to my mind while reading the article was that the colder parts of the western world have been steadily moving towards electric heating, while similar areas in developing countries still use wood/coal more often.
>Smoke exposure of any kind seems to have adverse health consequences over the long run.
It's more general than that. Fine particulate matter (like smoke/soot) tends to get in everywhere and with all the complex molecules in living organisms it's pretty much guaranteed that it will react with something and in large enough quantity that tends to cause disease.
I used to play with lead sheets as a kid. From roofing stuff my grandfather had around. It was fun because it was pleasingly malleable . Often wonder if it had any relationship with health issues
Elemental lead is way less toxic than organic lead compounds like they used to put in gas. Human body does not adsorb elemental lead very efficiently, but it loves that organic stuff. I played with lead as a child, it is a fun metal because you can bend it with your hands so easily or melt it on the stove and cast it in your sandbox(protip: don't use mom's good saucepan).
Elemental mercury is kind of in the same boat as elemental lead. It's poorly absorbed dermally and GI, so you need continuous exposure to be a real problem. It's worst when you're inhaling it, which is bad news because mercury does evaporate at room temperature, and especially when hot.
I doubt you encountered enough mercury, and for long enough, to be any problem unless you were doing something unusual with it. Eating a lot of fish is much more dangerous mercury-wise.
Air pollution in general is much better than it used to be. Particulates for example are known to be associated with memory problems: https://pubmed.ncbi.nlm.nih.gov/31746986/
> Researchers striving to understand the origins of dementia are building the case against a possible culprit: lead exposure early in life. A study spanning 23 years has now revealed that monkeys who drank a lead-rich formula as infants later developed tangles of a key brain protein, called tau, linked to Alzheimer's disease. Though neuroscientists say more work is needed to confirm the connection, the research suggests that people exposed to lead as children—as many in America used to be before it was eliminated from paint, car emissions, water, and soil—could have an increased risk of the common, late-onset form of Alzheimer’s disease.
General aviation (small planes) still use 100LL (low-lead) fuel.
Of course there are some newer GA planes that use JetA (kerosene) instead, but due to heavy regulations, it's really hard to make/certify new planes, so most people still fly 40+ year old carburetor planes.
>General aviation (small planes) still use 100LL (low-lead) fuel.
In vanishingly small quantities and even smaller concentrations (i.e. thinly distributed in the atmosphere making it hard for anyone to get a large dose) to the point which you can pick pretty much any other class of vehicles or source of lead and be reasonably sure it is causing more disease and death. I know it's easy virtue points to rag on it but leaded avgas is just not an issue. GA has no lobby or economic impact to speak of so it's not like it's sticking around through regulatory capture.
I wouldn't be surprised if some of the change is due to better recognition of other neurological disorders that were lumped in with Dementia in the past.
Why does the submission headline say "N. America" when the linked article doesn't? The linked article does say have this ridiculous sentence though: "One puzzling aspect of the decline is that it seems to be confined to Europe and the United States — it was not seen in Asia, South America or, from limited data, in Africa."
"Methods This analysis was performed in aggregated data from individuals >65 years of age in 7 population-based cohort studies in the United States and Europe from the Alzheimer Cohort Consortium. First, we calculated age- and sex-specific incidence rates for all-cause dementia, and then defined nonoverlapping 5-year epochs within each study to determine trends in incidence. Estimates of change per 10-year interval were pooled and results are presented combined and stratified by sex."
I thought it could be related to demographics, but they calculated using age-specific rates. Still, if the age bins are not small enough there could be some leftover bias (more older people in each bin for older countries). But that's for between-country comparison. The age distribution within the US itself might not have changed enough to account for the reduction.
> One puzzling aspect of the decline is that it seems to be confined to Europe and the United States [...] One leading hypothesis for the decline in the United States and Europe is improved control of cardiovascular risk factors, especially blood pressure and cholesterol.
My completely-devoid-of-evidence hypothesis is that over the past 25 years, increased globalization has reduced the number of menial jobs/tasks in those two continents, thereby increasing overall day-to-day mental exercise. This coupled with the rise of the internet gives citizens a needed mental outlet. The article mentions improved education as a possible reason, but not in the form of late-age mental exercise.
The exception to explain would seem to be developed Asian countries. Why does Japan not see a similar decrease?
They have a bunch of very significant societal and dietary differences that already contribute to high longevity. But you could compare “menial tasks” and see if that can explain some of the shift too. I’m guessing you’d see that Japan’s levels of menial tasks shifted in the same way as the western countries, but they didn’t see a similar change in dementia. That’s just based on my mental mode of effects here, would love to see some more analysis though.
There's likely benefit in staying mentally sharp, but this is true at any age.
I'm just a lay person, not a clinician or researcher, but it seems fairly evident to me that Alzheimer's and similar diseases are the result of:
-- Genetics
-- Environment
-- Lifestyle
So while doing puzzles or learning a second language might be good for us overall and ward off some forms of dementia, it doesn't feel like it's going to make much difference in whether we get Alzheimers (or Parkinsons, or Lewy-Body, etc).
I've always wondered if this simply isn't a case of having the causality wrong, that is to say people in old age who don't have alzheimer symptoms are more intellectually engaged.
Well today is your lucky day, because you can cease your wondering! The answer is "no".
In fact, any question you have that relies on thousands of doctors and professors in the field missing something obvious is always "no" (cf "never a compiler error").
The latter of course. Everyone who has given more than 10 seconds of thought to the issue has considered the opposite relationship because it's so obvious.
> My completely-devoid-of-evidence hypothesis is that over the past 25 years, increased globalization has reduced the number of menial jobs/tasks in those two continents, thereby increasing overall day-to-day mental exercise.
This fails on a couple levels to explain the headline:
1. 25 years is a very short time for someone to have a health-altering period of employment and then get old enough to develop dementia. The overall population with dementia is much larger, so in order to see a 13% drop, the final <10 years of work before you retire would need to increase your risk of dementia by several times.
2. It does not make sense that those people who are within 25 years of dementia would be able to suddenly switch from a menial job to an intellectual job. I would guess it is very unlikely (<10%) over any time horizon; the western world switched from manual jobs to service jobs but it's very difficult for people in those two categories to return to school and get an intellectual job.
3. I would hazard to guess that manual jobs are more intellectually stimulating than most service jobs. Working in a factory, building houses etc. includes tons of little bits of arithmetic and coordination. Phone/computer jobs and working in a store is mostly standing around or doing mind-numbing makework. At the very least, there's not a huge difference between the two- besides physical work, which is also very beneficial against dementia.
Quick note, this is why I said "jobs/tasks" and mentioned the "internet". Globalization (among other factors) reduces thoughtless tasks too, not just jobs.
Here's labour statistics for employment over the last 20 years[1] - I don't know if the changes are marked enough to support your theory, but I thought I'd give you some evidence to work with.
It's possible I'm not looking far enough back either - the cultural shifts that lead to this would have probably been at the point during these now senior citizens mid careers, not late - you don't usually get into a new industry when you're 55.
> One puzzling aspect of the decline is that it seems to be confined to Europe and the United States [...] One leading hypothesis for the decline in the United States and Europe is improved control of cardiovascular risk factors, especially blood pressure and cholesterol.
We have blood pressure and cholesterol meds now that force these "factors" down, but is there evidence that it has reduced the rise in actual heart disease?
I think they used to believe that mental exercises might slow down mental decline -- physical exercise certainly does -- but new evidence suggests this may not be the case:
Sigh, biology. We spend years working on the disease with no progress, and don’t manage to work out the cause before it starts going away by itself magically...
I have 3 best friends I’ve known for over 40 years. 3 out of 4 of us have a parent with dementia, including my mom. I know 3 other close friends whose parents have dementia as well. I know this is anecdotal but to me it looks like a crisis.
Dementia rates per capita rates are soaring due to an aging population and better medicine(we're able to keep sick people alive for longer who are at much higher risk of dementia). But dementia rates age groups are dropping.
My guess is the decrease in using aluminium cookware can explain this. Those areas that didn't see the dementia reduction are also likely poorer areas where they still cook using aluminium.
Not directly related to the article, but tangential: sometimes I wonder “how do I know that right now, I’m not in fact sitting in a wheelchair in an elderly’s home, with final stage dementia, and my dementia-ridden mind telling me I’m writing this comment on Hacker News as a healthy 40-something?”
- Lead gasoline stopped being sold(this is also theorized why crime dropped alot from the 90's)
- Pollution being down across the board due to better EPA standards and electric vehicles.
- Increased internet access and more games/puzzles with smart phones to stimulate the mind.
- Lead paint being taken very seriously as being detrimental to health. having specialized crews dealing with removing it, also asbestos being removed from society in the same way.