As More People Live Longer Why Are Rates of Dementia Falling?
The explanation favored by the authors is first that the general level of education of the population has increased and second that the prevalence of risk factors for the development of small blood vessel disease, which causes dementia, has declined. Old people have healthier lifestyles and do more exercise than they used to. The decline in smoking (oddly enough once thought to be protective against dementia, but now thought to promote it) may have had a marked effect.
The authors do not tell us why or how education should be a protective effect against dementia. Are neurons like muscles that atrophy if not used? Surveys have repeatedly shown that the educated are less susceptible to dementia than the uneducated, though we must always remember that statistical association is not causation.
However, pessimists need not despair, as there are grounds for thinking that improvement may not last. The authors warn that the huge increase in obesity and type II diabetes may reverse the trend. The fatties of today will be the dements of tomorrow, or at least of the day after tomorrow. That is, of course, if no treatment is discovered in the meantime that cures type II diabetes or prevents its deleterious effects, so that people will be able to have their cake and not suffer the consequences.
Then, of course, there is the question of the level of education. Is it rising or falling? I can’t help feeling that all those screens that young people spend most of their days playing with send out invisible rays that cause their brain to atrophy.