04/21/2004 at 01:00 AM EDT
In a stunning announcement on Tuesday, "Spin City" star Michael J. Fox said he is leaving the popular, 4-year-old ABC sitcom at the end of this season. "I feel that right now my time and energy would be better spent with my family and working toward a cure for Parkinson's disease. This does not mean I am retiring from acting, producing or directing," Fox, 38, said in a statement, "only that I want to relieve the strain of producing and performing a weekly network series." ABC said that it was too soon to decide on whether or not the series will continue without Fox, who plays New York's deputy mayor. In November of 1998, the actor revealed to PEOPLE Magazine that he was first diagnosed in 1991 with the degenerative neurological disorder that affects movement (and for which there is no known cause or cure). In March 1998, Fox had surgery to alleviate some of the worst tremors caused by the disease. He currently takes medication to control the milder symptoms, including rigidity in his hips and tremors in his hands.