It is not pollution, it is the noise and the low quality of sleep that causes dementia. Good sleep quality is important so the glymphatic system that cleans the brain of garbage while sleeping can work well. See this recent article: https://www.scientificamerican.com/article/nedergaard-how-th...
I'll add my speculative observation to the mix: Pollution aggravates my allergies, and when I'm having an allergic reaction, I have poorer sleep.
I suspect this result may be reflective of multiple factors that remain to be associated, qualified, and quantified with respect to this overall correlation.
That was my first thought. I went to visit a friend in the middle of nowhere in Norway last year. Coming back to a big city a week later I really noticed the level of noise you get in a big city and found it quite hard for the first few days back.
Had a similar experience recently overseas. Was shocked at how quiet it was--and I"m not like living in NYC or something back in the US--it is a clear difference from even a smaller city.
i wonder how much the road noise is affecting me especially since I quite like the overnight hum of the roads. a highway provides a much more even white noise experience while city road noise is more grainy.
the closest experience to the city hum that i could find in the country is probably the seaside, and i have to say, it is a very comforting experience.
In terms of pollution I'm assuming we are talking about NOx, PM2.5, and PM10. However it would be useful to understand if lead, banned in most countries around 2000, impacts dementia and whether this is now beginning to show itself within this study.
In the end there are huge range of causes that all impact these statistics.
For example, the rise of video games which may be a stronger explanation. One way to test this is if their are dips in violence around the release of GTA or other ultra popular games. With the method of action simply being fewer human interactions.
That said, the indirect evidence is even low levels of environmental lead contamination are significant over a population. Which suggests other things may cause similar issues without people noticing. EX: mad as a hatter
The correlation matches the phasing out dates in various places. The dates lead were discontinued weren't the same everywhere. Edit: how would games explain the geographic distribution? Areas with heavy lead contamination seem to have more of the effects, although no mention is made of game console/computer prevalence in any of the lead articles.
ED: This is in terms of the New York City drop in violence around 1993.
The data is just not as clear as your suggesting. After controlling for various things there is a percentage of the variation that links back to lead levels, but that does not mean it's the only or even the strongest impact in the raw data. Further, lead usage is linked to other things and as such is not completely independent.
PS: Remember, people move so lifetime exposure get's really hard to track accurately without regular blood tests.
I think the lead exposure = more violence connection is pretty well established. Leaded gasoline, while being the most studied connections out there, isn't even the only study in this regard.
For instance, there's this rather extensive study that shows higher homicide rates (among other things) in cities that used lead pipes for their water systems in the early 20th century.
I don't think there's a study (or may ever be) correlating reduced lung capacity/smoking and reduced/delayed risk for dementia in relation to the busy road belts.
Could there be some guarding reflex, that detects irregular sound or the absence of regular sounds and jump starts the sleeping mammal if predator presence is detected?
Hum. I live maybe 3000 feet from very busy road. Luckily there is forest between my home and the road. From the article it would seem that my "risk factor" is nil.
At 63 I am starting to think more about dementia risk factors.
I wouldnt worry too much. My grandfather has dementia symptoms and he's 90. You could have another 30 years.
One advice after watching him is to never quit your hobbies until you abosolutely have to. His mental decline was sharp after giving up hobbies he had for 40 years.
Be careful with the direction of causality here. It may be that giving up his hobbies hastened his dementia, OTOH it could easily be that the onset of his dementia led to him giving up his hobbies.
I don't worry too much. Just try to pay attention to what researchers are saying and controlling what I can with my lifestyle.
I work still and will continue to work till at least 67.
I'm a developer and development manager so I get to challenge my brain routinely at work. I consume nuts, lots of and a variety of tea, a little chocolate and some red wine to help with polyphenols [1]. Oh and Omega 3 fatty acid sources. I am actively getting my weight under control.
I play puzzles, board games and other things to stimulate my brain.
I've been sedentary most of my life. That has turned out to be not so good for my health. I do go workout now about 5 times a week. Been doing that for 3+ years.
I think your strategy of finding outside hobbies can be a real benefit.
My initial thought follows this line. Even if a subject doesn't experience actual sleep deprivation, the constant external stimuli are still omni-present, regardless of how well the conscious mind tunes them out. Perhaps sub+consciously parts of the brain never get any rest, even while sleeping?
I know I feel less refreshed if I fall asleep and media or traffic outside is constant. A hotel room facing a freeway often leaves me waking unrefreshed, which can be partially mitigated if the room's fan blower is left on for continuous, monotonous white noise masking.
Yeah, it can disturb your all-important REM sleep without causing you to fully awaken, so you're not aware that your sleep has been disturbed. You're just not as refreshed by morning.
Interesting about the fan blower. My wife started using that to prevent our young kids from being awakened by normal household noise. It reminded me of something I'd read years ago about people who worked in server rooms losing hearing sensitivity in the range of the constant low-level hum. Not sure how much exposure was required, but I encouraged her to use it sparingly.
I wonder if that's permanent hearing loss or temporary desensitization. It's not hard to imagine that the brain eventually starts to tune out a constant 60db server hum without any mechanical or permanent hearing loss.
Easy to imagine vascular dementia rates being higher due to air pollution, would be interesting to see if rates of non-vascular dementia, such as Alzheimer's are also higher.
It's equally easy to imagine that people who have a brain chemistry that makes them value things like quicker access to transport or a faster pace of life that makes them want to live in the centre of a city are also more susceptible to dementia though. This research has highlighted an interesting correlation that's worth studying, it's not necessarily showing that pollution is the cause.
A mechanic will have maybe one car running at any one time, maybe more if there are other mechanics in the same shop, and only for 8 hours a day. If you live near a road you'll have hundreds of running cars in your vicinity 24 hours a day.
General car mechanics probably not. I don't think they spend that much time next to running (and not just idling) engines. But I like that train of thought... how about professional drivers - truck, bus, taxi?
I was wondering lately why noise-cancelling technology is not used inside residential-buildings? Is there such a big difference between making this technology work inside my Bose-headphones vs an apartment? Street-noise seems pretty predictable and steady from afar.
I have long wanted to investigate advanced methods of reducing noise transmission between rooms; it seems to me that's a area that will clearly need improvement if we really expect cities of the future to be towers and condos instead of standalone houses. But you're correct that whatever solution does exist won't look / act like noise-canceling headphones.
I think that's an area that would benefit less from investigating and more from acting. But for some reason people think a room that's 20cm wider is "better" than one with sound-proofed walls.
You build the wall, you put in insulation, sand, water, glue and stick ceramic tiles on it. That could be a sound-insulating step two, but, you know. Has to be built that way.
Can't read the article because it's behind a paywall (sigh).
Any indication of how the researchers defined a 'major road'? Was it purely size or done by traffic throughput over time? Or did they be use air pollution / noise measurements instead?
But what proof is there that their adjustments covered every possible cause? I would suggest this is by definition impossible, since if we knew every possible cause for dementia, we would not need to do the study.
True, but there should be some rationale as to why they assume that normalization wrt the cofactors they've chosen are sufficient to provide for their conclusions.
Simply seemingly randomly choosing cofactors and then shrugging it off as good enough to draw conclusions from is sloppy. Typical, yes, but mean you shouldn't be skeptical of their conclusions, no.
Your specific concern was about socioeconomic status and because they answered that you now call it a random cofactor. Come on. You're not giving meaningful criticism. You're just being negative.