Parkinson's disease is a neurological disorder that has become the topic of much research lately. This neurological disease affects more than four million individuals around the world, making it the second largest neurological disease affecting people (National Institute of Health, 2013). The United States alone has about 60,000 new diagnoses made every year. Parkinson's disease can affect an individual of any age, however, the branch of this disease that people are most familiar with is late-onset Parkinson's disease. This part particular group encompasses those that are older than 55 years old. Young-onset or early-onset Parkinson's disease affects individuals before the age of 50, while juvenile-onset Parkinson's disease affects those under the age of 20 (NHGRI, 2011). No matter the age at which the disease first appears, its devastating effects are the same.
The symptoms of this disorder create great disruption in the affected individual's life. Parkinson's disease causes the degeneration of nerve cells that are directly connected to a region in the mesencephalon or midbrain of an individual. The exact area, called the substantia nigra, is the area in the brain that is charge of coordinating and controlling an individual's balance and movement (National Institute of Health, 2013). This accounts for the shaking or trembling associated with the disease. The innervation of these nerve cells is dependent on the ability of the neurotransmitter dopamine to cross the synaptic cleft of neurons. However, as these nerve cells begin to degenerate, the signals that dopamine is supposed to send to other nerve cells do not make it to the target destination, or drastically slow down (National Institute of Health, 2013). This usually occurs while the body is in a resting position and these shakes can affect all of the muscles of the limbs, such as legs, feet, arms and hands, and the face (Talan, 2012). Symptoms appear early on in the disease and get progressively worse, until all functionality is practically diminished. The key component to the symptoms is not having the ability to control these jerky, trembling motions.
Although Parkinson's disease is most recognized for its ability to create these tremors in individuals affected by the disease, there are numerous less known symptoms. Because of the role of dopamine in the innervation of nerve cells, stiffness and rigidity can develop, along with bradykinesia, or slow movement. As the nerve fibers begin to deteriorate, the signals to parts of the brain controlling movement are drastically slowed down, to the point where akinesia or the inability to move, could develop as well (National Institute of Health, 2013). Proper posture, balance, and coordination are diminished as the disease progresses. Because Parkinson's disease directly affects the brain, psychiatric and cognitive skills are greatly reduced. Many affected individuals develop depression, dementia, and may experience hallucinations. These disorders all contribute to the deteriorating effects on memory and judgment capacity.
The symptoms of Parkinson's disease are devastating for individuals afflicted with the disease and depending on the age of onset, these affects can be more damaging than others. Parkinson's disease is believed to be "sporadic" when it occurs in an individual that has no family history of the disease, attributing the onset to probable environmental causes (NHGRI, 2011). However, the most common characteristic of Parkinson's disease is the ability to develop within families continuously, insinuating a genetic component to developing this disorder. The mode of inheritance attributed to Parkinson's disease depends on the genetic chromosomes in question. It can either be autosomal recessive or autosomal dominant (NHGRI, 2011). That is, an affected individual must have inherited both affected recessive alleles from their parents in order to develop the disease, or inheriting just one mutated allele can cause the disease to develop if it is autosomal dominant. A mutation is attributed to the malfunctioning of nerve cells in the brain. The chromosomal genes that are mutated and affected are: LRRK2, SNCA, PARK2, PARK7, VPS35, UCHL1, GBA, PINK1, and ATP13A2 (National Institute of Health, 2013). Although the exact mechanisms that lead to an alteration or mutation in one of these genes are unknown, it is believed that the LRRK2 and/or SNCA gene on chromosome 6 is inherited in a dominant pattern, while a mutation on the PARK2, PARK7, and/or PINK1 gene on chromosome 4 causes for an autosomal recessive mode of inheritance (National Institute of Health, 2013). The...
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