CHICAGO — Joe Neglia was a retired government intelligence worker with Parkinson's disease (search) when he suddenly developed what he calls a gambling habit from hell. After losing thousands of dollars playing slot machines near his California home several times a day for nearly two years, Neglia stumbled across an Internet report linking a popular Parkinson's drug he used with compulsive gambling. "I thought, 'Oh my God, this must be it,"' he said. Three days after stopping the drug, Mirapex (search), "all desire to gamble just went away completely. I felt like I had my brain back." A Mayo Clinic...