sc
check age (years, not hours)
wear 'age item'
sc
check age (years, not hours)
rem 'age item'
sc
check age (years, not hours)

And you will see that the years in your score go up and down. Now, if the item affects age by 10, it will give you 10 years. For an arial or human or some other young race this is huge, at the most 10 years would be roughly 100 hours of game time for a human. For an elf instead, 10 years would be more like 8 hours of game time lost pre age death. I would imagine the same applies for wither. Solution: if you want a long lived charachter, play an elf.