Interesting. Not sure they truly accounted for everything, but if it holds water, I wonder if the mind’s attempt to blot out noise has other deleterious effects on the brain.
If noise is a risk factor for dementia, I think it’s most likely because it interferes with sleep.
Of course anywhere there is traffic noise, there are vehicle emissions. The authors tried to control for this by using a couple of general measures of air quality, but I think it’s possible that some undetected emissions may account for this effect.
The paper is here:
Limitations include lack of information on lifestyle factors, which are recognised risks for dementia.1 However, our models included several socioeconomic variables, which are highly associated with lifestyle.45 Besides, adjustment for lifestyle could result in overadjustment, as important lifestyle variables (eg, smoking, diet, alcohol consumption, and physical activity) were shown to be potentially associated with transportation noise
That bit is interesting to me - they aren’t controlling for a bunch of factors at the individual level, but those factors are correlated to traffic noise levels. I’m not saying their approach is wrong, as much as the analysis is pretty tricky to control for a lot of confounding variables.
I’d assume the correlation of traffic noise levels to lifestyle variables would be similar to the socioeconomic ones - people with less money have to put up with more traffic noise AND have less time/money for diet, exercise, etc. The trick (as always) is figuring out which of these variables is correlated / associated, and which are actually causal. I wonder if they’d get a different result if they ran the analysis the other way (testing socioeconomic factors against dementia, and controlling for noise.)
That’s an excellent assessment. I had not read the article, but wondered if all socioeconomic issues were fully accounted for.