A:
The Salah of a person who suffers enuresis is valid for himself. (Part No. 7; Page No. 393) Allah (Exalted be He) says,
So keep your duty to Allâh and fear Him as much as you can
and
Allâh burdens not a person beyond his scope.
The Prophet (peace be upon him) said,
When I command you to do anything, do of it as much as you possibly can.
Moreover, there is a difference among scholars concerning the validity of Salah performed by healthy people behind this man. The soundest opinion is that their Salah is valid. But other people who are healthy should lead people in Salah in order to avoid such difference.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.