Parkinson’s disease, also known as idiopathic parkinsonism, is a chronic disorder of neurologic origin with clear neurodegenerative characteristics. Parkinson’s disease develops in people in middle and late life and has a definite morbid anatomy. The cause of Parkinson’s disease has not been established, yet its biochemical pathology is clear (Adler & Ahlskog, 2000). The disease is progressive and places a considerable burden on patients, their families, or people who provide care. Parkinson’s disease has been associated with increasing rates of morbidity and mortality, increasing disability and lowering life expectancy (Simuni, 2007). In addition, PD (abbreviation for Parkinson’s disease) places a heavy economic burden since treatment is associated with considerable costs and use of medical resources (Dowding et al, 2006). The name of the disease is believed to immortalize Doctor James Parkinson from Great Britain, whose monograph Essay on the Shaking Palsy (1817), first described the symptoms and signs of what has come to be considered one of the most widespread disorders of neurologic nature in the Western clinical practice (Adler & Ahlskog, 2000).
The aim of this paper is to explore the epidemiology, etiology, risk factors, pathophysiology, clinical expression, and burden of Parkinson’s disease. Based on current academic research, it sums up the major clinical concerns about PD and its likely progression.
Parkinson’s disease has been diagnosed in approximately one million Americans. The population affected by PD outnumbers the overall number of cases of muscular dystrophy, ALS (or amyotrophic lateral sclerosis), and multiple sclerosis. Every year over 40, 000 people in the United States get diagnosed with Parkinson’s disease, yet numerous cases remain undetected. Statistically, 10 million people live with PD across the globe. Parkinson’s disease is more likely to affect male population; its incidence grows with age (Weintraub et al, 2008). Besides, it has been found that African Americans are less subject to PD than people of Caucasian origin (Simuni, 2007).
Etiology of Parkinson’s Disease and its Risk Factors
The symptoms of the disease are typically rooted either in the neuropathologic condition of PD or some other forms of the disorde. With reference to the former, nearly 90% cases are found to be sporadic, without clear etiology. The remaining 10% are identified as having a genetic origin; they are related to 6 or more gene mutations. These forms of PD are more often found in young-onset cases of Parkinson’s disease (Simuni, 2007).
Researchers established that PD’s secondary forms may result from medications use, as well as from toxins, consequences of infected central nervous system, or vascular disorders. Despite the ongoing research into the causes of the disease, the only established risk factor is increasing age. It has also been assumed that PD may be associated with rural living, working with solvents, drinking well-water, and being exposed to both herbicides and pesticides. Yet, the relation of these factors to PD has not been found unequivocal (Simuni, 2007).
Pathophysiology of Parkinson’s Disease
Second only to Alzheimer’s disease, PD is characterized by the following hallmark signs: tremor, rigidity, bradykinesia, and postural instability. The hallmark of the pathological nature is “degeneration of dopaminergic neurons in in the substantia nigra pars compacta (SNc), resulting in depletion of striatal dopamine”. The latter is a neurotransmitter that monitors both inhibitory and excitatory outflow of what is known as basal ganglia (McNaught & Olanow, 2006, p. 530).
A few surviving neurons comprise Lewy bodies, also known as eosinophilic intracytoplasmic inclusions. These are partically made up of a vast number of proteins. This accumulation of protein is thought by some researchers to contribute prominently to the pathogenesis of PD, sporadic as well as familial. Lewy bodies’ presence is an essential element of pathologic clinical conformation of PD’s diagnosis. While neurodegenration of SNc is associated with Parkinson’s disease, it is also true that this process is not limited to it. In other words, neuronal loss along with the formation of Lewy bodies takes place in other regions of human brain, too. This may lead to non-motor and motor characteristics of PD (Simuni, 2007).
Clinical Expression of Parkinson’s Disease and its Course
Simuni (2007) and Rezak (2007) observe that the cardinal motor signs of PD are resting tremor, postural instability, slowness of patient movement (bradykinesia), and rigiddity. Patients report impairment in writing (micrographia) and doing other activities (e.g. fastening buttons). The clues that a patient has Parkinson’s disease include: asymmetric onset, response to levodopa, and step-by-step progression.
Non-motor features of Parkinson’s disease may be divided into several categories. Neuropsychiatric features include depression, panic attacks, anxiety, cognitive dysfunction, apathy, dementia, confusion, psychosis; Impulse Control Disorders include pathologic gambling, binge eating, hyper-sexuality, obsessional behavior, some other behavior of repetitive nature. PD is characterized by sleep disorders, too. These include insomnia, restless legs, rapid-eye movement behavior disorder, sudden-onset sleep, vivid dreams, sleep apnea, daytime somnolence, and sleep-disordered breathing. The dysfunctions of autonomic nature include hyper-salivation, sexual dysfunction, constipation, dysphagia, bladder disturbances, diaphoresis, choking, xerostomia, orthostatic hypotension, diaphoresis. Finally, sensory features encompass paresthesias, olfactory dysfunction, and, typically, pain (Weintraub et al, 2008).
Burden of Parkinson’s Disease
The biggest concern linked to the burden of PD is Health Related Quality of Life. Weintraub et al (2008) report that the findings of an authoritative U.S. study reveal that the perception of Health Related Quality of Life is considerably worse in patient diagnosed with Parkinson’s than in patients diagnosed with 8 other conditions. Just a few of these conditions are: stroke, diabetes, and heart disease (Gage et al, 2003). Increased mortality is another big concern. As for caregiving services, they, too, deal with the burden of sustaining Health Related Quality of Life (Weintraub et al, 2008)
It is predicted that the number of patients with PD will grow dramatically. This will go along with higher rates of utilization of medical resource and higher healthcare costs. Research has demonstrated difficulties in providing PD diagnosis and establishing direct causes of the disorder. Researchers are yet to learn to handle co-morbid symptoms of PD that related to neuropsychiatric, non-motor kind. These are cognitive impairment and depression. Dealing with these symptoms may even be more important than with other given the fact they are more disabling to any patients than symptoms of motor kind.