You’re being sarcastically dismissive, but this is a real possibility. The real world is complicated and disorders with environmental effects are often multi-factorial.

Air pollution might not be the direct cause, it might be a proxy measurement that is correlated with some other factor or factors that contribute to dementia risk. For example, do areas with higher air pollution measurements also have higher or lower rates of something else that is actually contributing to the dementia directly? Do they simply correlate with overall development of the area, and therefore areas with poor pollution numbers also have high levels of water pollution?

It's even worse... dementia sufferers are the ones emitting these particles ;-)

Thanks, got a good laugh out of this one.

Probably not that, but it could be something else that also correlates with pollution like living in big cities, or working in a factory, walking more/less, noise levels, lifestyle, etc

Well, in some cases we know that they do.

Dementia is linked to diabetes. And diabetes risk is increased for African-Americans. And African-Americans live in high-pollution urban areas for entirely historical reasons.

So some amount of the causation here does go in the way opposite to what a person might naively suspect.

> Dementia is linked to diabetes. And diabetes risk is increased for African-Americans. And African-Americans live in high-pollution urban areas for entirely historical reasons

A is correlated with B. B is causally correlated with C, i.e. C causes B. (C is correlated with D.) Hence C causes A.

Let’s replace. Flowers are correlated with bees. Bees are caused by hives. (Hives are correlated with trees.) Hence, hives cause flowers.

Loosely, yes. Formally, no.

We know that diabetes causes some amount of dementia and that flowers cause no amount of bees. And so on. Your example is specious, and obviously so.

Outlive (book) talks extensively about dementia risk and Alzheimer's as "type 3 diabetes".

People who are poorer and have worse health are predisposed to live in cheaper dwellings, many of which are closer to roads and thus more noisy and with more air pollution.

People who are poorer and have worse health, also have an increased incidence of dementia, seemingly independently of the number of particles in their dwellings.

I’m not sure this is a completely valid statement. Take Ontario - the most expensive places to live are in Toronto with the most traffic, the cheapest places are more rural without that heavy traffic and thus less pollution.

There might be some hidden variable at play that's correlated both air pollution that is really causing the dementia. Like street noise. Not saying it's likely, but it's not impossible.

In rural areas it's pesticides. And in urban areas it's dry cleaners and air pollution. Parkinson's Plan is worth a read for the kind of details you can't get on a single article

Another Red state theory about Blue cities ?