“Parkinson's disease is a brain disorder that causes tremors, difficulty walking and coordination. » (1). The disease occurs when nerve cells in the brain are destroyed and slow the production of dopamine; Without dopamine, the brain cannot transmit messages to the rest of the body either. This is why tremors begin and lack of coordination and movement appears since the brain cannot tell the body what to do correctly. There are no exact causes of the disease; it is considered a multifactorial trait. A multifactorial trait “may be determined by two or more factors; often several genes interact with each other or with the environment” (5). It is also believed that certain medications, whether prescribed or sold on the street, may cause PD symptoms. These symptoms include slower automatic movements such as blinking, difficulty walking, swallowing and coordination; as well as visible tremors and muscle pain. The people tested, more often elderly people, have difficulty completing the movements and are somewhat jerky in the movements tested. There is no cure for Parkinson's disease. Doctors and therapists try to control symptoms with medications, but they also advise exercise, which releases dopamine to counteract some of the effects. In some severe cases, surgery is used to destroy the brain tissue causing the disease, but this is only in rare cases. Besides all the physical problems that accompany this disorder, mental problems also arise. According to one doctor, “at least 40% of Parkinson’s patients suffer from an attack of major depression.” (2) However, most of the time, the patient's depression comes in short bursts and does not last long for the most part. Physical impairments are immediately visible and are the “defining characteristics”...... middle of document ......d, mood and behavior” princetonwellbeing.com. July 25, 2000. April 1, 2014(4) Findley, Leslie. “The economic impact of Parkinson's disease” elsevier.com 2007. April 1, 2014. (5) Rosenberg, Leon E. Human genes and genomes. New York: Elsevier, 2012. Print. April 4, 2014.(6) “Understanding Parkinson’s disease.” Parkinson's Disease Foundation. NP, 2014. Web. April 6, 2014. .(7) Gwinn, Katrina. “Genetics and Parkinson’s disease: what have we learned?” » Parkinson's Disease Foundation. NP, 2009. Web. April 6, 2014..(8) Tanner, Caroline M. “Environmental factors and Parkinson's disease: what have we learned? » Parkinson's Disease Foundation. NP, 2011. Web. April 6, 2014..(9) OMIM. Johns Hopkins University, 2014. Web. April 9. 2014..