[Reason077]

It is not pollution

PM2.5 particles from vehicle emissions are small enough to penetrate the blood-brain barrier and have been shown to end up in brain tissue.

Even if it isn't a direct cause of dementia, air pollution contributes to cardiovascular diseases which are themselves risk factors for dementia.

[pasbesoin]

I'll add my speculative observation to the mix: Pollution aggravates my allergies, and when I'm having an allergic reaction, I have poorer sleep.

I suspect this result may be reflective of multiple factors that remain to be associated, qualified, and quantified with respect to this overall correlation.