RAWALPINDI, Pakistan—Each day, Cpl. Hamid Raza helps strap Cpl. Mohammed Yakub to a physiotherapy bench, lifts it and wipes the sweat off his bewildered comrade's forehead. Eyes darting, Cpl. Yakub often screams and grunts through the procedure, flailing his hands.

"Traumatic head injury," Cpl. Raza says softly. "He realizes it's me, and he tries to speak, but he can't. He can't eat, he can't talk, he can't remember the words."

...