Can how you spend your time in adulthood make you smarter? Does it slow a decline of intelligence?
For example, take 2 people of equal intelligence who get the same college degree. After college, they take the same job for the same company. In their free time, one watches sitcoms and other “fluff” TV, never reads non-fiction, stays involved mainly with their home and family, etc. The other person rarely watches TV, is an avid reader of fiction and non-fiction, is active in clubs and community service, takes community college classes for fun, etc.
Will person 2 become smarter over time? Will person 1 lose intelligence or plateau?
Opinions are OK, but actual factual answers are great, too.