Parkinson's disease (PD) is a degenerative disorder of the central nervous system mainly affecting the motor system. Early in the course of the disease, the most obvious symptoms are movement-related; these include shaking, rigidity, slowness of movementand difficulty with walking and gait. Later, thinking and behavioral problems may arise, with dementia commonly occurring in the advanced stages of the disease, and depression being the most common psychiatric symptom. Other symptoms include sensory,sleep, and emotional problems. The main motor symptoms are collectively called "parkinsonism", or a "parkinsonian syndrome".
The disease can be either primary or secondary. Primary Parkinson's disease has no known cause, although some atypical cases have a genetic origin. Secondary parkinsonism is due to known causes like toxins. Many risks and protective factors have been investigated: the clearest evidence is for an increased risk in people exposed to certain pesticides and a reduced risk in tobacco smokers. The motor symptoms of the disease result from the death of cells in the substantia nigra, a region of the midbrain. This results in not enough dopamine in these areas. The reason for this cell death are poorly understood but involves the build-up ofproteins into Lewy bodies in the neurons. Where the Lewy bodies are located is partly related to the expression and degree of the symptoms. Diagnosis of typical cases is mainly based on symptoms, with tests such as neuroimaging being used for confirmation.
Treatments, typically the antiparkinson medications L-DOPA and dopamine agonists, improve the early symptoms of the disease. As the disease progresses and neurons continue to be lost, these medications become ineffective while at the same time produce acomplication marked by involuntary writhing movements. Diet and some forms of rehabilitation have shown some effectiveness at improving symptoms. Surgery to place deep brain stimulation have been used to reduce motor symptoms in severe cases where drugs are ineffective. Research directions include investigations into new animal models of the disease and of the potential usefulness of gene therapy, stem cell transplants, and neuroprotective agents. Medications to treat non-movement-related symptoms of PD, such as sleep disturbances and emotional problems, also exist.
In 2013 PD was present in 53 million people and resulted in about 103,000 deaths globally. Parkinson's disease is more common in older people, with most cases occurring after the age of 50; when it is seen in young adults, it is called young onset PD. The disease is named after the English doctor James Parkinson, who published the first detailed description in An Essay on the Shaking Palsy, in 1817. Several major organizations promote research and improvement of quality of life of those with the disease and their families. Public awareness campaigns include Parkinson's disease day (on the birthday of James Parkinson, 11 April) and the use of a red tulip as the symbol of the disease. People with parkinsonism who have increased the public's awareness of the condition include actor Michael J. Fox, Olympic cyclist Davis Phinney, and professional boxer Muhammad Ali.
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http://bmcneurol.biomedcentral.com/articles/10.1186/1471-2377-10-49 efficacy and acceptability of selective serotonin reuptake inhibitors for the treatment of depression in parkinson's disease: a systematic review and meta-analysis of randomized controlled trials by petros skapinakis et al., bmc neurologybmc series ¿ open, inclusive and trusted201010:49 doi: 10.1186/1471-2377-10-49