Parkinson's Disease Research Paper

Essay 86: Parkinson's Disease and the 1918 Flu Pandemic Parkinson's disease (PD) is a degenerative motor disorder resulting from the progressive loss of dopaminergic neurons in an area of the brain known as the basal ganglia, in particular two clusters of cells called the substantia nigra. The manifestations of PD appear when 80% or more of the dopamine producing neurons have been destroyed. Symptoms of PD include difficulty initiating movement (bradykinesia); a shuffling gait; the classic pill rolling hand tremor; a blank facial expression; muscle rigidity; and in 10-15% of cases, the onset of dementia late in the course of the disease. Nearly a century ago, in the wake of the 1918 influenza pandemic, which left as many as 50 million

Part of the reason for this uncertainty stems from the unique nature of the influenza virus itself. Unlike most other viruses, influenza contains a segmented genome comprised of eight distinct sequences of RNA. The virus not only undergoes genetic point mutations, known as antigenic drift, over the course of a flu season but also a phenomenon known as antigenic shift. Antigenic shift occurs when two strains of influenza viruses infect the same cell then proceed to mix and match entire segments of their genomes. This genome swapping ability leads to radically altered (and occasionally deadly) viral progeny, as occurred in later flu epidemics in 1957 and 1968. Incidentally although several hundred thousand Americans died in those epidemics, there was no spike in the number of cases of postencephalitic Parkinsonism

All of these animals are capable of spreading the virus to humans; in fact, the H1N1 strain most closely resembles an avian influenza virus. Whether the survivors of the 1918 pandemic who went on to develop postencephalitic Parkinsonism were infected with a unique variant of H1N1 (or perhaps with multiple strains of influenza) will probably never be known for certain. In addition to a viral etiology, several other theories have been proposed to account for the pathogenesis of PD. As yet, no consensus has emerged as to a specific cause or causes. In contrast to the etiology, the epidemiology of PD is well characterized: approximately 1% of Americans over age 65 will develop Parkinson's. The disease shows no predilection for any particular ethnic group, and both genders are affected equally. Although PD can strike younger people, they represent roughly 10% of the estimated 3 million cases of PD in the United