Michael J. Fox on Parkinson's Battle

June 8 -- For Michael J. Fox, this past Wednesday brought together his three great passions: acting, his family, and the search for a cure to Parkinson's disease.

It was the screening of his new animated Disney film, Atlantis: The Lost Empire, in which Fox is the voice of adventure star Milo. The screening was to benefit Fox's foundation, which funds research on Parkinson's. Fox also announced that he and his wife, Tracy Pollan, are expecting their fourth child.

Fox left the hit TV series Spin City last year, two years after disclosing that he has Parkinson's disease. He didn't pick the behind-the-scenes role in Atlantis to help shield the disease, which affects his speech and movement. But he acknowledged that he enjoys voiceovers more now.

"It's great, it works out really well, but I would do them anyway and, and had done them anyway," Fox told Good Morning America. "I think I enjoy them more because of the disease in a strange way, in the sense that I'm just totally liberated when I go in."

But he doesn't do them as a way to stay in the film business.

"I'm actually really enjoying the hiatus from doing it," Fox said.

The Greatest Lesson

But is he intending to go back into television or movie acting?

"I've learned that my intent doesn't mean a whole lot," Fox said. "And that's been the greatest lesson of the whole thing. So, you know, every day is an adventure."

He can see himself doing other films in the future and can see things happening that would enable him to do things that he cannot do now, he said.

Research into Parkinson's disease is promising, though it's hard to say which type of research stands the best chance of helping to cure the disease, Fox said.

"But obviously the things that come to mind are stem cell research, and then obviously all the stuff, mapping the genome, you know, trying to identify genes, the Parkinson gene," Fox said.

He's now 40, but by the time he's 50, he is expecting progress.

"Oh, I guarantee it," he said. "I mean whether or not I benefit from it ... I'm not saying I'll sit here in front of you 10 years from now and have gone past it." He is impressed with the research he's seen.