Good question. I'm not so sure you'll find such an animal, but I can offer you some suggestions. Remember the things that make geriatric patients different from other patients: their reactions to drugs, polypharmacy, fewer indicators of infection, as well as diseases/disorders that are at an increased risk of contracting or exhibiting once the pt becomes elderly.
That's really the trick, not studying geriatrics in particular, I think. But maybe someone else would offer something else