Michael J. Fox, No Doubt's Tom Dumont and more celebrities have been diagnosed with Parkinson's disease over the years. Parkinson's is a nervous system disorder that worsens in the body over time, per the Mayo Clinic. While every person's battle with Parkinson's can look different. Symptoms include tremors, stiffness, slowing of movement, trouble balancing, slurring speech and more. There is no cure for Parkinson's, but medication can help a patient manage their symptoms. Keep scrolling to see which stars have battled the condition: Michael J.