Parkinson’s Disease
British physician and pharmacist James Parkinson first described the disease that now bears his name in 1817. The cardinal symptom is a general and progressive difficulty with movement, followed by deterioration in mental function.
When diagnosed early, symptoms of Parkinson’s disease can be managed fairly successfully with drugs for as long as eight to 15 years. But often the malady is not recognized soon enough, because it begins with very 1._____ symptoms. Tense muscles in an arm or shoulder, for example, tend to send people to orthopedists, not neurologists. Fatigue, depression or sudden outbreaks of sweating are typically pegged to other common problems.
These conditions often remain mild for a long time; nine to 12 years can pass before the disease 2._____ asserts itself. But by then a large percentage of cells in certain brain regions have already died. Individuals begin to lose their fine-motor coordination: they cannot thread a needle, and their handwriting becomes tiny and hard to read. Soon everyday tasks such as combing hair, buttoning a shirt or tying shoes become impossible. Patients become 3._____ others, and their quality of life declines dramatically. As movement slows, so do mental processes. Thinking drags, and speech drawls.
Scientists have known since the late 1920s that 4._____ the disease advances, neurons in the midbrain die off. Neuroscientists still cannot say definitively what triggers the trouble. In some cases, physical brain damage from accidents or blows to the head from boxing, for example, may start the process. Heavy metals and pesticides have also been implicated by some epidemiological and animal studies.
Though lacking a culprit, experts concur that some mechanism causes brain proteins to misfold, which in turn kills neurons. A genetic defect is 5._____ in five to ten percent of cases, and the aberrations provide interesting clues.
Konrad Schmidt & Wolfgang Oertel, Scientific American