My husband Coy was 76 and already diagnosed with dementia when he started seeing a wonderful geriatrician. My father's pcp was a geriatrician when Dad was in his 70s or maybe younger. When mother needed a new pcp in her 80s I got her to a geriatrician.
I think these were all decisions.
Now I'm wondering when I should consider switching to a geriatrician. I will be 69 next week. My chronic illnesses are diabetes and depression. I have had several changes of pcp in the last 12 years -- not by my choice, but by changes in the clinic's staff. I am not dissatisfied with my present pcp but not particularly devoted to her, either.
For most people I've known, it seems somewhere around 75 is when the body starts going downhill fast. Maybe that is a good target age for a geriatrician.