In reply to Flinticus:
I'm mid 50s and suffering from arthritis in several finger joints. I find taping the affected joints to support them helps (as opposed to the more usual taping between the joints for supporting pulleys). It reduces their mobility but doesn't actually seem to affect their performance.
Training with open hand grips and avoiding crimps puts less strain on the joints. Also, as soon as possible after training sessions I put my hands in iced water to reduce inflammation. On multi day climbing trips where icing isn't possible, I take ibuprofen.
And finally, on the benefits of keeping fingers mobile, I've found that if I play the piano* after a wall session my fingers stiffen up less overnight.
*Other finger mobility exercises are available