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Air pollution directly linked to increased dementia risk

(www.nature.com)
275 points rntn | 4 comments | 07 Sep 25 13:13 UTC | HN request time: 0.001s | source
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dynm ◴[07 Sep 25 15:20 UTC] No.45158964[source]▶
This article repeats the common mistake of conflating correlations and causality. The main results are (1) that PM2.5 exposure is correlated with dementia in humans, (2) some experimental results with mice. This does not establish causality in humans. The paper is careful to stay juuuust on the right side of the line by carefully using "associated" in the right places. But the press release discards that pretense at rigor and jumps straight to full-on claims of causality in people:

> Long-term exposure accelerates the development of Lewy body dementia and Parkinson’s disease with dementia in people who are predisposed to the conditions.

I think it's entirely possible (perhaps even likely) that this is true. But the paper does not show it.

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1. goalieca ◴[07 Sep 25 15:57 UTC] No.45159316[source]▶
The maps in the article wasn’t even super clear when you inspect it visually. Didn’t read the study but it can’t be that strongly correlated.
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2. hn_throwaway_99 ◴[07 Sep 25 16:24 UTC] No.45159598[source]▶
I was going to say something similar. Obviously I was just taking a visual look and not doing any rigorous analysis, but California certainly sticks out like a sore thumb. It has many areas in the Central Valley and Southern California with very high PM2.5 levels, but no "purple" areas with high dementia levels in the state. I also just read the article and not the study but I'd hope they give an explanation for that glaring outlier.

I'd be interested to compare the disease map with a map of average income, because at first glance the disease data looks to be correlated with wealth, and we already have tons of research that shows that wealth is one of the biggest determinants of health outcomes in the US.

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3. mikeiz404 ◴[07 Sep 25 17:14 UTC] No.45160066[source]▶
I noticed this too. I do wonder what it would look like if you controlled for relocation (moving to another region and then developing symptoms), disease onset (both maps are for the same time ranges), and the types of pm 2.5 exposure.
4. selimthegrim ◴[07 Sep 25 18:40 UTC] No.45160974[source]▶
New Orleans is another one.