Tazren Talamar
Gaidin
Has she aged, per se? We have seen very old Aes Sedai like Verin and Cadsuane herself ride around the country on horseback, and sleep rough. They sometimes mention feeling their age, but not to the extent of (say) walking with a stick or even having trouble keeping up with younger traveling companions. It's also mentioned that grey hair is a sign of truly extreme age. All of this makes me think that they've really only aged into the equivalent of their fifties at most. The Oath Rod doesn't cause faster aging; it limits maximum lifespan.
I see that as a result more of the very perfect health they'd live in, with constant Healing of diseases and other things that accompany old age generally, unless the One Power itself guarantees graceful aging. There are people who are above 70 and 80 and are still very spry and healthy.
Since swearing on the Oath Rod tightens their skin physically, to me, that's what prevents peopele from getting wrinkles. Their bodies are aging, which the gray hair indicates.
Age for a channeler depends on the One Power. The Oath Rod even seems to take this into consideration, since almost all of the most ancient Aes Sedai we see are very strong in the One Power (Adeleas and Vandane being the only exceptions). Most Aes Sedai die somewhere between 200 and 250 years. Cadsuane is ~290, Romanda is the same age. In New Spring, Meilyn was considerably older than Cadsuane, all three very strong channelers. Gitara was rumoured to be over 300, and being a Keeper, it's reasonable to assume that she was at least above average strength in the OP (since most people to hold positions of power in the White Tower are fairly strong).
If the Oath Rod is a ticking timebomb, why would it take One Power strength into consideration when determining someone's maximum lifespan? Wouldn't there just be a cap at, say 200 or 250 years?
It makes more sense to me that it would decrease the rejuvenating effects of the One Power, so that people bound age faster than those who haven't sworn any Oaths.