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Comment by nnain | Hacker News Reader

I really don’t know how to trust such research anymore. Delhi and nearby areas have serious air pollution Issue (Actually large part of the north India belt going upto Pakistan has a problem with dusty air, especially in winters), but Alzheimer’s is not a serious issue here.

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Just people finding relationships in data, and likely getting tripped up with intervening variables.

https://en.wikipedia.org/wiki/Mediation_(statistics)

Without any causal model, a lot of this medical research is just staring too hard at scatter plots of correlated variables. I heard the other day that herpes is correlated with Alzheimer's. Is herpes correlated with air-pollution? Probably. Do we know what the real cause of Alzheimer's is? No way.

Yeah, I go about telling people the importance of knowing that “Correlation is not causation”.

Most people just don’t care to understand it, “But the scientists said xyz, who are you to question them?”. “Erm, someone who likes stats and common sense”

What's the life expectancy in Delhi, and for what fraction of their lives have old people in Delhi been exposed to the high levels of air pollution?

See this is the slight, unnecessary, condescending attitude in west. Life expectancy in India is fine in people who can afford ok food and place to live. There’s a lot of poverty and poor people seemingly have lower life expectancy, which lowers the avg. And yeah pollution would have an effect, but it’s definitely not like people die early so we don’t have data on Alzheimer’s. My grandparents lived past 80, and only one of them took some diabetes medicine. Otherwise they weren’t dependant on drugs till their last years.

I think it depends more on the time that people are exposed to pollution for. I don't know for how long this Issue has been existing, but I don't think that any significant increases are going to happen for the first 30 years of such an Issue.

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