April 9, 2008
Problems with memory, thinking and speaking and trouble carrying out day-to-day activities like balancing the checkbook or preparing meals are often attributed to Alzheimer's disease, an ailment that afflicts some five million older Americans. But in some cases, the problems may be due to dementia from Parkinson's disease, the second most common degenerative nerve ailment after Alzheimer's.
April is Parkinson's Awareness Month, and, is is the case with Alzheimer's, nobody is sure what causes most cases of Parkinson's, a disease that affects some 3 percent of older Americans. In a small percentage of cases, Parkinson's has been linked to defective genes. But the vast majority of cases strike older men and women between the ages of 55 and 70, and in some patients with memory and thought problems, the disease is sometimes mistaken for Alzheimer's disease.
In addition to memory loss and other symptoms of dementia, Parkinson's typically causes movement problems. Slowed movement and rhythmic "pill-rolling" shaking of the hands, especially when people are at rest or feeling anxious, are common symptoms. Muscle stiffness, difficulty in changing positions, loss of balance, decreased facial expression, and difficulty swallowing may also occur.
Named after the English physician who first described it in 1817, Parkinson's disease occurs because of the progressive death of nerve cells in the brain. Like Alzheimer's, symptoms usually occur gradually and may not be noticeable at first, and they may be attributed simply to "aging." But also like Alzheimer's, symptoms continue to worsen over time, and there is no cure. Both diseases are devastating for those who get them, and for family members who care for loved ones with the disease.
The overlap of symptoms between Parkinson's and Alzheimer's leads some researchers to believe the two diseases may share underlying causes in common, but no definitive links have been found. Some studies have shown that brothers, sisters and other first-degree relatives of those with Parkinson's disease may be at increased risk for dementia. Other research has shown that those with Alzheimer's have an increased risk of developing Parkinson's as well.
Alzheimer's and Parkinson's disease sometimes both occur in families. Researchers have uncovered some genes that may lead people to be at increased risk for one or both disorders. Furthermore, the plaques and tangles that occur in the brains of those with Alzheimer's disease and the protein deposits called Lewy bodies that occur in the brains of those with Parkinson's disease have features in common.
Furthermore, pioneering work in uncovering the underlying causes of Alzheimer's disease may also provide clues to the causes of Parkinson's. Researchers like Nobel prize winner Paul Greengard at The Rockefeller University has provided critical clues to the way that nerve cells communicate with one another in the brain. Better understanding of these basic mechanisms may lead to new drugs and other treatments that can ease, or even halt, the progressive decline of Alzheimer's disease and Parkinson's disease.
The Fisher Center for Alzheimer's Research Foundation is funding critical research into the underlying causes of Alzheimer's disease, the leading killer of older Americans.
Robert L. Nussbaum, M.D., Christopher E. Ellis, Ph.D.: "Alzheimer's Disease and Parkinson's Disease." New England Journal of Medicine, April 3, 2003, Volume 348, Number 24, pages 1356-1364.
Walter A. Rocca, M.D., M.P.H., James H. Bower, M.D., J. Eric Ahlskog, Ph.D., M.D., et al: "Risk of Cognitive Impairment or Dementia in Relatives of Patients With Parkinson Disease." Archives of Neurology, Volume 64, Number 10, 2007, pages 1458-1464.