There are so many other factors. The generations now suffering from cognitive decline/Alzheimers are generations that smoked, took recreational drugs, worked with asbestos, solvents, other chemicals that wouldn't be allowed now, ate and drank foodstuffs that were sometimes adulterated with other substances, were exposed to smog, methane and other dodgy gases from leaky pipes, lead pipes, lead paint, DDT, dreadful dentistry with mercury/amalgam fillings, so on and so forth. Whatever we read now written by young journalists and researchers with sentimental ideas of the good old days - I was there and it wasn't so.