This “study” makes an assumption so stupid that if the study’s conclusion is correct, its authors should be completely safe from dementia. It just assumes that “education” is automatically something that makes people smarter. But the reality is that “education” is just a word, and many people receiving an “education” are actually receiving nothing more than harmful political indoctrination that makes them dumber and less able to reason intelligently. So undefined “education” can’t have the homogenous effect they claim.
The probands in this study were probably for the most part older people who got their degrees in the 1970s or earlier - i.e., before higher education went completely to the dogs.
Regards,