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"Evidence builds that dirty air causes Alzheimer’s, dementia"


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The particles are too fine for many air pollution sensors to accurately measure, says Saffari, who works in a lab led by Constantinos Sioutas at the University of Southern California (USC) here. Typically smaller than 0.2 µm in diameter, these “ultrafine” particles fall within a broader class of air pollutants commonly referred to as PM2.5 because of their size, 2.5 µm or less. When it comes to toxicity, size matters: The smaller the particles that cells are exposed to, Saffari says, the higher their levels of oxidative stress, marked by the production of chemically reactive molecules such as peroxides, which can damage DNA and other cellular structures.  [...]


If the finding holds up in the general population, air pollution could account for roughly 21% of dementia cases worldwide, says the study’s senior author, epidemiologist Jiu-Chiuan Chen of the Keck School of Medicine at USC. [...]


Deepening the concerns, this month researchers at the University of Toronto in Canada reported in The Lancet that among 6.6 million people in the province of Ontario, those living within 50 meters of a major road—where levels of fine pollutants are often 10 times higher than just 150 meters away—were 12% more likely to develop dementia than people living more than 200 meters away.

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My MIL's doctor told her a few years ago that for her health she should consider moving north where the air is cleaner.  My in-laws are in Pickering, Ontario (30 min east of Toronto).  My wife's grandmother had Alzheimer's and my MIL has shown early signs.


Maybe her doctor was ahead of the curve on this one. 

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Whether it's a risk factor for dementia or not, air pollution certainly isn't good for any of us. But this may be one more piece of evidence on the mountain that should already be pushing us to cleaner technologies.


The World Health Organization has already concluded a few years ago that diesel emissions cause lung cancer... And I've seen things about how bad it is for cardiovascular health.


Every time I see a big diesel truck spewing black soot every time it accelerates from a traffic light, I can't wait for diesel to go away.



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Would add the following for constructive purposes.


The two most relevant and interesting studies I've come across about this specific topic (causality in Alzheimer's) are:




The field of nanotoxicology remains relatively controversial.

At this point, genetic factors are felt to be major contributors and prevalence increases exponentially with age.

It seems that, essentially, the rising prevalence of dementia is related to population cohorts living longer.


A word on the article. I possibly spent not enough time on it and on the premises supporting the conclusions but the Toronto article mentioned is a retrospective study of exposures. These are labeled as observational and are very weak indicators of causality. But they form the basis of further studies. This is because the conclusions are based on statistical calculations using odds ratios and relative risks associated with attempts to retrospectively "control" for other potential exposures or causes. These studies are notorious for suggesting spurious correlations or correlations with no material meaning with reality ie breast cancer risk related to the number of bathrooms in the house.


Historical tidbit: In the old days, people suffering from tuberculosis were sent to sanatoriums for the fresh air. At some point, many of these places were transformed into fancy touristic resorts.



Alzheimer's disease is a nasty disease and hopefully explanations and treatments will be forth coming.

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