The same biochemical changes in the brain that cause the hallmark physical symptoms of Parkinson's -- tremors, slowed movement, rigidity, balance loss -- can also affect mood, said Dr. Jeff Bronstein, a neurologist in the Movement Disorder Program at UCLA.
"Obviously getting the diagnosis can make people depressed," he said. "But we also know that there's a much higher incidence of depression even before the disease is recognized. We think it's one of the early symptoms."
Parkinson's disease occurs when cells in the brain that produce a chemical called dopamine sicken and die, unleashing a cascade of symptoms that can include constipation and sleep disturbances early on, leading to movement troubles later in the progression of the disease. Some, but not all, Parkinson's sufferers also experience cognitive troubles and
The National Institute of Neurological Disorders and Stroke in
Peak incidence is around 62 years old, Bronstein said.
"He's at the right age," Bronstein noted, of the 63-year-old Williams.
Susan Schneider, the late comedian's wife, revealed his illness Thursday. "Robin's sobriety was intact and he was brave as he struggled with his own battles of depression, anxiety as well as early stages of Parkinson's disease, which he was not yet ready to share publicly," she said, in a statement.
Bronstein said that "early stages" of Parkinson's usually refer to the period soon after diagnosis, when symptoms are likely to be "quite mild."
Some patients with Parkinson's disease progress through the symptoms more quickly than others, said Dr. Mindy Bixby, a neurologist and movement disorder specialist at Orange Coast Memorial Medical Center in Fountain Valley. She said patients who exercise often fare better.
Medicines currently available to treat Parkinson's do not slow the disease, but effectively control its symptoms, Bixby and Bronstein said.
Patients with Parkinson's usually die from the same causes as most people, causes such as heart attacks or cancer, Bronstein said.
"With today's treatments, you can have a long life, and high quality of life," he added. "It's the rule, rather than the exception, that people can do well for many years, and there are new therapies coming down the road. It's not a death sentence."