This is incredibly well put Shaid :)
Some of these wears and tears turns on/off certain genes within the human genomes and hence, varieties of diseases.
It is interesting you say in Nigeria the prevalence of dementia is low. I came across an Alzheimer's disease international consensus by WHO, and Africa was among the lowest rates. However, it is speculated that it might be due to different assessment criteria, which often depends upon cultural aspects and diagnostic practices.
All the best my dear :)
thanks :)