@ age 68 with mild dementia, she should still have well over 10 years of life left. That's more than enough time to completely destroy what's left of the country.
You apparently don’t know what you are talking about in the case of vascular dementia:
“Although treatment can help, vascular dementia can significantly shorten life expectancy. The average survival time from diagnosis is around four years.”
http://www.nhs.uk/Conditions/vascular-dementia/Pages/Introduction.aspx
“Patients who are diagnosed with vascular dementia are given a three to five year life expectancy.”
My father in law had vascular dementia. From the time we started noticing, but didn’t know what it was, til he died was 10 years. The last 3 years of his life were the worst.