Maybe not Alzheimer’s specifically, but dementia. There is lots of evidence for this. High blood sugar causes blood vessels in the brain to deteriorate. Here, for example.

I think earlier generations were tougher, and the weak were winnowed out earlier.

It’s certainly true that a much higher percentage of us are making it to old age, and being kept alive by modern medicine with conditions that might have killed us in a previous generation, and now just result in dementia. A natural thing to study would be whether the increased cognitive decline is there once you control for other health conditions.

Autism and its spectrum is perhaps another clue. In the latest Science magazine assessment these disorders are now being found on 1/59 births; and WHO says 1/50 births…both world wide. One large Texas study showed a strong correlation between areas of environmental pollution and ASDs. And there are lots of mutations associated, but none are very or highly associated with the disorder. So we have a quandary in etiology but most researchers believe there is some world wide exposure to something toxic that is causing ASD. Of course similar mechanisms could be involved with dementia.

I have wondered personally about whether we could be harming ourselves by breathing in nano particles of asphalt—worldwide—or maybe similar erosive nano particles of automobiles and truck tires. They wear out and particles go somewhere. But we really do not know. We could be getting neural damage from some widely used food like coffee or food additive like sodium benzoate.

I think molecular biology tools will figure this stuff out
pretty soon.

ocrates: Writing vs. Memory
Posted on September 29, 2013 by Janet AuCoin LeBlanc
In Plato’s Phaedrus, Socrates calls into question the propriety and impropriety of writing. Throughout his discussion with a colleague, Socrates insists that writing destroys memory and weakens the mind (Ong, 2002). To support his theory, Socrates recounts a story in which two Egyptian gods, Theuth and Thamus, debate the merit of introducing ‘letters’, or writing, to the people. Theuth argues that the ‘letters’ “…will make the Egyptians wiser and give them better memories; it is specific both for the memory and for the wit.”(Plato, n.d.). In response, Thamus states that ‘letters’ “… will create forgetfulness in the learners’ souls…” (Plato, n.d.). Thamus believed that the people would become dependent on the written word and cease to use their own memories. He also believed the written word would lead people to become “hearers of many things”, appear as though they were all-knowing, but to actually be learners of nothing. With the extension of the written word into both mass-produced print and digital formats, and observation of our tech-reliant society, it appears that Thamus’ beliefs may have had an element of truth.

And on that other topic about memory, whatever it was, I forget…
https://www.health.harvard.edu/mind-and-mood/the-effects-of-marijuana-on-your-memory

Cannabis contains varying amounts of the potentially therapeutic compound cannabidiol (CBD), which may help quell anxiety. However, there’s no question that marijuana (the dried flowers and leaves of the cannabis plant) can produce short-term problems with thinking, working memory, executive function, and psychomotor function (physical actions that require conscious thought, such as driving a car or playing a musical instrument). This is because marijuana’s main psychoactive chemical, THC, causes its effect by attaching to receptors in brain regions that are vital for memory formation, including the hippocampus, amygdala, and cerebral cortex. The extent to which long-term use of marijuana (either for medical or recreational purposes) produces persistent cognitive problems is not known.

Well, here’s two for sure (me and AesopSpouse), plus our combined 6 siblings that I’m quite sure about.
I could add in some cousins (well, except for one) and friends from college that I’m also confident of, and some other friends made later in life ditto.
Pretty sure my cohort is not unique.

Maybe that’s enough “righteous people in Sodom” to forestall total destruction.