Bob Hoskins, the 69-year-old actor in "Hook" and "Who Framed Roger Rabbit," has announced his retirement from the profession because of a Parkinson's disease diagnosis, according to news reports.

TMZ reported that Hoskins was diagnosed with the nervous system disorder last year in the fall.

Parkinson's disease affects up to 1 million people in the United States, with 60,000 being diagnosed each year, according to the Parkinson's Disease Foundation. Worldwide, the condition affects anywhere from 7 million to 10 million people.

Experts aren't sure what exactly causes Parkinson's, but it's likely a combination of genes and the environment, the Mayo Clinic reported. Researchers also know that clumps of substances in the brain, called Lewy bodies, may somehow play a part in Parkinson's.

Parkinson's is more common when people are in middle or older age, and it's also more common in men and in people who have a closely related family member with the condition, according to the Mayo Clinic.

There are four hallmark symptoms of Parkinson's disease, that tend to progress from a mild state to a more severe state: hand, arm, face or leg tremors; limb and trunk stiffness; problems with balance; and becoming increasingly slower with movement, according to the National Institutes of Health. As these symptoms get worse, they can impair a person's ability to complete daily functions.

There is no cure for Parkinson's disease, but certain medications can help with the symptoms. A surgical procedure called deep brain stimulation may also be used for certain advanced cases, according to the Mayo Clinic.

Because Parkinson's is a chronic condition -- meaning it doesn't go away, and may continue to get worse throughout time -- medical costs can add up. The Parkinson's Disease Foundation reported that for the average person with the condition, drug costs can be about $2,500 per year, while surgical treatments can cost as much as $100,000.

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