[He lowers his head, exhausted. These bald spots are...man, he's going to look rough in 40 years.]

I was forced to restore my age when it was reversed artificially in the past. The device worked, but it was untested. That could be one source.

A week later, I was exposed to negative proton energy. I was fine for several months after this, but it could be a delayed reaction. [Does it make sense? No. But it's canon.]