Honestly this seems to me to be much more likely a reason than industrial society environmental factors. My father was in his early 80s before he could no longer “fake away” the mental decline he was experiencing due to Alzheimer’s. At 86 and moving into stage 7 of the disease.
I have to think people reaching that advanced an age was relatively rare in pre industrial times, coupled with the fact that today Alzheimer’s affects only about 10% at age 65. You would need a large population reaching that age and beyond to the later stages where the disease becomes problematic before it would become noticeable in a society.
This complete fallacy that "people didn't live that long" can't die soon enough. Mortality numbers are horribly skewed by high birth and infancy mortality rates and a spike for military-aged individuals, but people that made it to forty didn't wait to turn fifty then keel over and die.
But still high infant mortality and spike in deaths of military aged people, as well as more primitive medical (lack of antibiotics etc.), There was not as many people that made it to the advanced ages where the results of dementia becomes particularly problematic for the people around them. Because of that smaller group, and a portion of that smaller group being affected, it might not be a widespread and noticeable societal issue. Couple that with a less complex lifestyle and you may not notice the dramatic differences as we do today of the afflicted.
For instance…my father about 4 years ago lost all ability to successfully use a TV remote, telephones (To call), to drive, etc. He could read, was able to eat, handle self hygiene needs, etc. Our society notices the decline sooner because of the tech we use. However, 2000 years ago, the decline may not have been as noticeable until it hit the most advanced stages. At the advanced stages, hygiene, eating, etc… become difficult to impossible and these later stages back then would likely bring quicker physical declines and death than they do today.
The "mortality was skewed by infant mortality" myth can't die soon enough. Yes the life expectancy being 35 didn't mean everyone died at 35, but your mortality at any given age was substantially higher than today. Whereas today living into your 70s is nearly a given and people have decent odds of remaining healthy into their 80s, in the past living to such ages was exceptional. Of course it happened on occasion, but if you look at the ages people actually died of natural causes, it was typically between 50 and 65. Even when people were noted for their incredibly long life, it was still rather short compared to today. Louis XIV, for example, was the longest reigning european monarch of all time, living to the ripe old age of 76, outliving his son (who died at 49) and grandson (dead at 29), to be succeeded by his great grandson who would live to be 64. The modern life expectancy in France is 82.
Not really. Ben Franklin died at 84, for example. Jefferson died at 83.
Being poor, however, has always sucked. Being wealthy always meant you lived longer.
The difference is that wealth concentration was much more strongly localized and concentrated in the past. And the famous people, who you have heard of, were generally the more wealthy people.
I have to think people reaching that advanced an age was relatively rare in pre industrial times, coupled with the fact that today Alzheimer’s affects only about 10% at age 65. You would need a large population reaching that age and beyond to the later stages where the disease becomes problematic before it would become noticeable in a society.