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Announcing Thursday that he has Parkinson's disease and Lewy body dementia, former Utah Jazz coach Jerry Sloan joined public figures like Michael J. Fox, Muhammad Ali and the late Robin Williams in fighting the progressive illnesses for which there is no cure.

While Parkinson's predominantly affects motor control, resulting in slowed movement, rigid muscles, impaired balance and tremors, Lewy body dementia attacks a patient's cognitive ability, leading to visual hallucinations, depression, sleeping disorders and memory loss.

"We do know that the prognosis is worse for Lewy body dementia," said Denise Skuster, a neurologist with Intermountain Healthcare's Salt Lake Clinic. "It's a more widespread pathological process in the brain."

Its cause is unknown, but Lewy body dementia, Alzheimer's and Parkinson's diseases appear to be linked, based on similar evidence seen in the brains of patients, according to the Alzheimer's Association.

Skuster said treatment for both Parkinson's and Lewy body dementia focuses on limiting the disease's symptoms, and not the disease itself.

And while those treatments are not new, she said, there have been recent advancements in diagnosing the illnesses, particularly imaging tests that identify Lewy body dementia. Those tests, and increased recognition of Lewy body dementia, make it the second most common form of dementia behind Alzheimer's disease.

"Because this is a hard disease to diagnose," Skuster said, "the fact that we have a better diagnostic test is really encouraging."

But Skuster said it is challenging to give a prognosis for each of the diseases. Like patients with Alzheimer's, she said, most people with Parkinson's disease die from a cause other than the illness.

"As the disease progresses, you become less able to care for yourself," she said. "Walking becomes a problem. Eating becomes a problem. People die from becoming debilitated."

It can be particularly difficult for patients and their families to endure the progressive deterioration, she said. "To lose your mind and to know you're losing your mind is a terrible disease."

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