FRIDAY, July 6 (HealthDay News) -- Parkinson's disease patients experience declines in physical abilities and quality of life several years before the degenerative disease is diagnosed, new research finds.
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In women, the declines started about 7.5 years before diagnosis, while in men, declines were noted at three years prior to diagnosis, according to the study in the June 2 issue of the Journal of Parkinson's Disease.
Parkinson's disease occurs when the neurons that produce dopamine, a crucial brain chemical, in certain regions of the brain die. Symptoms, which worsen over time, can include tremors, stiffness, slurred speech and trouble walking.
Researchers examined information on 51,000 men enrolled in the Health Professionals Follow Up Study and 122,000 women enrolled in the Nurses' Health Study.
The men completed questionnaires about their health-related quality of life, including physical functioning, limitations due to physical and emotional problems, mental health issues and pain. The women answered questions about their physical functioning.
Researchers identified 454 men and 414 women with Parkinson's disease. Until about 7.5 years before diagnosis, physical function for both men and women was similar to that of men and women who were not later diagnosed with Parkinson's.
From this point on, however, women with the disease began to experience a decline in their physical function, while men's decline in physical function and well-being began around three years prior to diagnosis.
"We observed a decline in physical function in [Parkinson's disease] patients relative to their healthy counterparts beginning three years prior to diagnosis in men and seven and a half years prior to diagnosis in women," study lead investigator Natalia Palacios, of Harvard School of Public Health, said in a journal news release. "The decline continues at a rate that is five to seven times faster than the average yearly decline caused by normal aging in individuals without the disease."
Researchers said the study suggests that the Parkinson's disease process may start years before symptoms become obvious.
"This result provides support to the notion that the pathological process leading to PD [Parkinson's disease] may start several years before PD diagnosis," Palacios concluded. "Our hope is that, with future research, biological markers of the disease process may be recognizable in this preclinical phase."
-- Mary Elizabeth Dallas
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SOURCE: Journal of Parkinson's Disease, news release, July 2, 2012