Parkinson's disease is a chronic and progressive movement disorder affecting nearly one million Americans. Symptoms can include tremors; slowness of movement; limb rigidity; and problems with balance and coordination. The cause isn't known, and there is no cure at present. But there are treatment options such as medication and surgery to manage symptoms. Now, UPI reports a new study shows singing can also bring relief to Parkinson's patients. Researchers at Iowa State University say singing significantly improves the muscle activity involved in swallowing and breathing control--two functions gravely affected by Parkinson's. Other benefits include improvements in mood, stress and depression.