The data to support the conceit just isn’t there. There may be small shifts due to things like “diet”, “microplastics” or “alumina” for example, but stopping leaded gasoline alone probably was more impactful than all of those insults combined. More likely what would have presented as dementia will end up being preceded by other disease categories like cancers, autoimmune conditions, or blood vessel diseases.
Looking at the data from several aging projects, it looks like not only are there individuals who appear to be largely immune to dementias, but the proportion of those individuals is growing rather than shrinking.
What if dementias are not a discrete disease or syndrome at all, but are always an artifact of some other systemic insult? Finding dementia patients without some type of co-morbidity is nearly impossible clinically, and lottery rare post autopsy. Thinking about this in the context of recent research which really strongly points toward the overlap of ataxias and cognitive impairment, dementia almost never exists alone.
Is dementia/cognitive impairment more accurately a symptom rather than condition in it’s own right? Should we be thinking of it like hypertension, which is always a symptom rather than a disease?
edit: It’s just weird that despite the nearly trillion dollars and world moving amount of effort into addressing dementias, the only significant prophylactic we have at this point are vasodilators, especially PDP-5 inhibitors. More than diet, exercise, education, etc. If we are thinking of the brain as part of the nervous system and the nervous system as a consistent unit, rather than segregating the brain as a special organ on it’s own, this makes a hell of a lot more sense than a specific plaque. It seems more like the plaques are causing “hyper-local mini strokes”, rather than the plaques themselves being toxic.