Although more research needs to conducted, studies have demonstrated that in later life, better cognitive function is associated with larger social networks and engagement in social activity.
In my personal experience with family members, it has become evident that hearing loss contributes greatly to social isolation. There are types of hearing loss and situations where hearing aids either aren't effective or aren't utilized. Not having a hearing aid means that you can't keep up with conversations and will often choose to opt out of activity, thus increasing the likelihood of isolation and depression.
Much like learning clapping games when we're kids and dances when we're teens, we could learn American Sign Language. What if it were normalized starting with adults making a concerted effort to learn and then seeking opportunities either in-person, online or via phone video to practice? Would using your hands' full range of motion, decrease stiffness in older age? If everyone knew it, it would certainly decrease self-imposed isolation for those who opt out of activities because they can't hear.
If you're interested in testing my theory, check out the free beta site https://www.signschool.com. It's a gamified learning platform that tracks your progress. Learn with with your spouse, your children, you grandchildren, your neighbors...just learn. A worthy goal for all of us it be able to communicate with more people for a longer time, keep the fingers moving and stay sharp all at the same time. Let's get going!
Not sure if you have hearing loss?
See the quiz here: https://tinyurl.com/test4hearing
Lastly, if you know someone who could benefit from either a captioned old-school phone or from a mobile phone with a captioning app, then just search online for your state and "telecommunications access program." Many states have programs that don't have income thresholds and even provide in-person technical assistance in setup.
Evans IEM, Martyr A, Collins R, Brayne C, Clare L. Social Isolation and Cognitive Function in Later Life: A Systematic Review and Meta-Analysis. J Alzheimers Dis. 2019;70(s1):S119-S144. doi:10.3233/JAD-180501