"There were a lot of factors impacting Williams," Krakower added. "He had the drug addiction, depression and heart problems. Throwing on the Parkinson's is just one more factor."
According to the U.S. National Institutes of Health (NIH), Parkinson's disease is a movement disorder that occurs when nerve cells in the brain don't produce enough of the brain chemical dopamine. Symptoms begin gradually and then progress. They include trembling of the hands, arms, legs, jaw and face; stiffness of the arms, legs and trunk; slowed movement; and poor balance and coordination.
As symptoms worsen, people may have trouble walking and talking, and can experience problems such as depression and sleep difficulties.
There's no cure for Parkinson's disease, but there are medicines and therapies that can help improve symptoms, according to the NIH.
Williams' suicide Monday refocused public attention on depression, its sometimes link to substance abuse and, in tragic cases, suicide.
He was last seen alive at his suburban San Francisco home about 10 p.m. Sunday, according to the Marin County coroner's office. Shortly before noon on Monday, the Sheriff's Department received an emergency call from the home, where he was soon pronounced dead. Sheriff's officials said Tuesday that Williams committed suicide by hanging himself.
Williams, who was 63, had struggled for decades with substance abuse and depression, and routinely made references to those personal battles in his comedy routines.
"Cocaine is God's way of telling you you are making too much money," he would quip.
Williams had been dealing with severe depression recently, said his publicist. Early last month, he had checked himself into a rehab facility for substance abuse, according to published reports. His publicist told People magazine at the time
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