Unclear. The cohort most exposed to atmospheric lead was born between 1951 and 1980 [1]. This study only measures those born before 1948.
(To the extent the study supports a hypothesis, it's the null. Given atmospheric lead increased from 1890 onwards, until about the 1980s [2], if lead were the culprit we'd expect to see more dementia among the study's younger generations. Not less.)
Two things we know for sure now, and probably knew pretty well even then, chlorinated hydrocarbons and heavy metals are not good for the environment. They have their industrial uses but need to be used with care.
Unclear. The cohort most exposed to atmospheric lead was born between 1951 and 1980 [1]. This study only measures those born before 1948.
(To the extent the study supports a hypothesis, it's the null. Given atmospheric lead increased from 1890 onwards, until about the 1980s [2], if lead were the culprit we'd expect to see more dementia among the study's younger generations. Not less.)
[1] https://www.pnas.org/doi/full/10.1073/pnas.2118631119
[2] https://www.sciencedirect.com/science/article/abs/pii/S10406...