Ask HN: Tools to help families with Alzheimer's/dementia

A close family member of mine is developing Alzheimer's disease. He can still take care of himself but is getting more difficult to converse with. He loses things easily, and every once-in-a-while gives us a scare because he decides to leave the house and doesn't tell us about it.

What tools, devices, apps, etc do you recommend that could improve his safety and/or quality of life (and also our peace of mind)?