Parkinson's impairs quality of life

WASHINGTON (AP) — Rocker Ozzy Osbourne has died at the age of 76, just weeks after his farewell concert and about five years after announcing he had Parkinson's.

Here's what you need to know about the disease:

It's a neurological disorder that deprives people of control over their movements. It usually begins with tremors and is characterized by slow movements, a shuffling gait, stiff limbs, balance problems, and difficulty speaking.

In the United States alone, approximately one million people live with Parkinson's, and 10 million worldwide, according to the Parkinson's Foundation. It usually appears after age 60, although it can sometimes occur before age 50.

The exact cause is unknown, but Parkinson's develops when cells that produce one of the brain's chemical messengers, dopamine, begin to deteriorate and die.

Dopamine carries signals to parts of the brain that control movement. Parkinson's symptoms appear after enough dopamine-producing cells die, resulting in insufficient amounts of this neurotransmitter in the brain.

According to the foundation, most experts believe that genetic and environmental factors are behind the disease. Dozens of genetic mutations linked to Parkinson's have been discovered, and genetics accounts for 10% to 15% of all cases.

Other factors suspected of increasing risk include head injuries, exposure to pesticides and herbicides, and location.

There is no cure, but treatments exist, including medications that influence dopamine levels and a surgically implanted device that blocks tremors. Patients also benefit from physical and occupational therapy.

Symptoms worsen over time, usually slowly. The severity of symptoms and the speed with which they progress vary widely among patients. In advanced cases, people may be unable to walk or care for themselves. They may also suffer from depression, as well as memory and thinking problems.

Although Parkinson's disease itself is not considered fatal, people can die from complications of the disease, including lung problems, as muscle weakness makes it difficult to cough and swallow.