This Pajamas Media piece from July relates the results of a Lancet study on dementia among those over 65 in poor countries:

As in richer countries, the chances of developing dementia were lower among the better-educated. The particular protective factor was found to be literacy, not number of years at school, because in some countries literacy is not necessarily the outcome of prolonged schooling. We in the west know all about that.
 
If literacy protects against the development of dementia, ask the authors, why is there no epidemic of dementia in countries with aging populations but low literacy rates among the elderly? They answer that it is probably because those who are demented die disproportionately in such countries. However, they have not shown that there is no such epidemic; and furthermore, there is no proof that the statistical correlation between illiteracy and dementia is a causative one.

For the moment, however, the prevailing orthodoxy is that reading (and other such educated activities) create a “cognitive reserve” that protects against the development of dementia. The educated do not show signs of losing their mind because they have more of it to use, just as very rich people rarely suffer poverty.
 
It seems a good plan, then, to continue to read. Personally, I was planning on it anyway.