Homeshare
https://en.wikipedia.org/wiki/Homeshare
Homeshare (also called sharehome) is the exchange of housing for help in the home. A householder, typically an older person with a spare room, offers free or low-cost accommodation to another person in exchange for an agreed level of support. The support may include companionship, shopping, household tasks, gardening, care of pets and, increasingly, help to use the computer. Homeshare thus provides a solution to the needs of two groups of people - those in need of affordable housing, often younger people, and those in need of some support to live at home, usually older people. Homeshare programmes, many run by voluntary bodies, have taken root in at least thirteen countries worldwide, some of them with public funding.
5 Unexpected Things That Seem to Lower Dementia Risk
https://gizmodo.com/5-unexpected-things-that-seem-to-lower-dementia-risk-1848185368
In the way of all science reporting, be careful of correlation vs. causation.