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June 12, 1997

Alzheimer's & Parkinson's: A link?

Parkinson's disease is a neurological disor- der that progressively robs people of control over their movements. In the majority of cases, it doesn't affect thinking or memory.

Alzheimer's disease is likewise a progressive neurological disorder. But normally it takes away its victims' memories and thinking powers without impairing their motor skills.

And yet…

"It turns out that when you perform autopsies on people who have died of Alzheimer's disease, up to 30 percent of them will show the changes of Parkinson's disease in the parts of the brain where classic Parkinson's occurs," said Steven DeKosky, director of Pitt's Alzheimer Disease Research Center.

In addition, the victims' brains often show the widespread presence of distinctive, Parkinson's-associated cellular bodies called "Lewy bodies," DeKosky said. In cases of classic, or pure, Parkinson's disease, Lewy bodies are confined to the base of the brain.

DeKosky will talk about what he called "the mysterious overlaps" between Parkinson's and Alzheimer's during the June 14 Pitt Symposium on Parkinson's Disease, 2-5 p.m., in the Frick Fine Arts auditorium.

"At this point, we can't explain the existence of this overlap group of people who develop both the dementia symptoms of Alzheimer's and the movement disorders of Parkinson's disease. But it looks as if the association of the two diseases is too high to just say this is bad luck," DeKosky said. "Alzheimer researchers are faced with sorting out that relationship and the causes of simultaneous Alzheimer's and Parkinson's." In comparing and contrasting the diseases, DeKosky noted that Parkinson's targets just one of the brain's neurotransmitters — dopamine — whereas Alzheimer's attacks a number of neurotransmitters throughout the brain.

The U.S. Food and Drug Administration has approved two drugs that control some symptoms of Alzheimer's, just as L-dopa controls the symptoms of Parkinson's in most people with that disease. "What we haven't figured out with either disease is how to prevent the damage from progressing even as we treat it with symptom drugs," DeKosky said.

If treatments aren't found to slow the disease's progress by at least five or 10 years, Alzheimer's could "break the country," according to DeKosky.

Currently, about 4 million Americans suffer from dementia; 3 million of them have Alzheimer's. "The projection is that by the year 2030 or 2040, the number of Americans with dementia will grow to 14 million, with 75 percent of them having Alzheimer's.

"We don't have enough money under Medicare or Medicaid to cover the people who have Alzheimer's now, much less deal with the psychological and social and emotional strains that are caused by this disease. What happens when the number of people with Alzheimer's triples in just a few decades?" While Alzheimer's is a worldwide scourge, it is more prevalent in developed countries with relatively sophisticated health care. "The fastest growing population group in the United States today is people who are 85 years of age or older," DeKosky said. "A generation ago, life expectancies were in the 60s. Not only were there fewer elderly people, and thus fewer cases of Alzheimer's, but people who got the disease tended to die more quickly than they do now." — Bruce Steele

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