United Kingdom, Sept. 9 -- Michael J. Fox admits his Parkinson's has got "harder over the years" but he's promised to find a cure.

The 65-year-old actor, best known for his roles in the likes of Back To The Future, Spin City and most recently Shrinking, has raised over $3 billion in research for the disease since founding the Michael J. Foundation back in 2000.

Reflecting on balancing the spotlight with handling his own symptoms, he told PEOPLE magazine: "Of course, things have gotten harder over the years.

"[But] I'm privileged to commit my time and energy to bringing everything I've got to help cure this disease."

Michael effectively became a public face of the disease when he launched the foundation, and he pointed out that his own...