Something of Interest
Parkinson's disease (PD) is a degenerative disorder of the central nervous system. The motor symptoms of Parkinson's disease result from the death of cells in a region of the midbrain (substantia nigra) that plays an important role in reward, addiction, and movement; the cause of this cell death is unknown. Early in the course of the disease, the most obvious symptoms are movement-related; these include shaking, rigidity, slowness of movement and difficulty with walking and gait. Later, thinking and behavioral problems may arise, with dementia commonly occurring in the advanced stages of the disease, whereas depression is the most common psychiatric symptom. Other symptoms include sensory, sleep and emotional problems. Parkinson's disease is more common in older people, with most cases occurring after the age of 50.
Parkinson's disease is idiopathic (having no known cause), although some atypical cases have a genetic origin. Many risk and protective factors have been investigated: the clearest evidence is for an increased risk of PD in people exposed to certain pesticides and a reduced risk in tobacco smokers. The pathology of the disease is characterized by the accumulation of abnormal aggregates of protein that develop inside nerve cells (Lewy bodies). Lewy bodies are the pathological hallmark of the disorder, and the distribution of the Lewy bodies throughout the Parkinsonian brain varies from one individual to another. The anatomical distribution of the Lewy bodies is often directly related to the expression and degree of the clinical symptoms of each individual. Diagnosis of typical cases is mainly based on symptoms, with tests such as neuroimaging being used for confirmation.
Modern treatments are effective at managing the early motor symptoms of the disease, mainly through the use of drugs. As the disease progresses and neurons continue to be lost, these drugs eventually become ineffective at treating the symptoms and at the same time produce a complication marked by involuntary writhing movements. Diet and some forms of rehabilitation have shown some effectiveness at alleviating symptoms. Brain surgery has been used to reduce motor symptoms as a last resort in severe cases where drugs are ineffective. Research directions include investigations into animal experimentation of the disease and of the potential usefulness of gene therapy, stem cell transplants and neuroprotective agents (preservation of neuronal structure and function). Medications to treat non-movement-related symptoms of PD, such as sleep disturbances and emotional problems, also exist.
The main motor symptoms are collectively called parkinsonism, or a "parkinsonian syndrome" which is a neurological syndrome characterized by tremor, hypokinesia (decreased bodily movement), rigidity, and postural instability. Parkinsonism shares symptoms found in Parkinson's Disease, from which it is named; but parkinsonism is a symptom complex, and differs from Parkinson disease which is a progressive neurodegenerative illness.
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, April 11) and the use of a red tulip as the symbol of the disease. People with parkinsonism who have increased the public's awareness include actor Michael J. Fox, Olympic cyclist Davis Phinney and professional boxer Muhammad Ali.
PD traditionally has been considered a non-genetic disorder; however, around 15% of individuals with PD have a first-degree relative who has the disease. At least 5% of people are now known to have forms of the disease that occur because of a mutation of one of several specific genes.
PD is the second most common neurodegenerative disorder after Alzheimer's disease and affects approximately seven million people globally and one million people in the United States. The prevalence (proportion in a population at a given time) of PD is about 0.3% of the whole population in industrialized countries. PD is more common in the elderly and prevalence rises from 1% in those over 60 years of age to 4% of the population over 80. The mean age of onset is around 60 years, although 5–10% of cases, classified as young onset, begin between the ages of 20 and 50. PD may be less prevalent in those of African and Asian ancestry, although this finding is disputed. Some studies have proposed that it is more common in men than women, but others failed to detect any differences between the two sexes.
The costs of PD to society are high, but precise calculations are difficult due to methodological issues in research and differences between countries. The annual cost in the UK is estimated to be between 449 million and 3.3 billion pounds, while the cost per patient per year in the U.S. is probably around $10,000 and the total burden around 23 billion dollars.
A physician will diagnose Parkinson's disease from the medical history and a neurological examination. There is no lab test that will clearly identify the disease, but brain scans are sometimes used to rule out disorders that could give rise to similar symptoms. People may be given levodopa (a drug for treatment of Parkinson's disease) and resulting relief of motor impairment tends to confirm diagnosis. The finding of Lewy bodies in the midbrain on autopsy is usually considered proof that the person had Parkinson's disease. The progress of the illness over time may reveal it is not Parkinson's disease, and some authorities recommend that the diagnosis be periodically reviewed. Alzheimer's disease can secondarily produce a parkinsonian syndrome.
Computed tomography (CT) and magnetic resonance imaging (MRI) brain scans of people with PD usually appear normal. These techniques are nevertheless useful to rule out other diseases that can be secondary causes of parkinsonism such as tumors.
Caffeine consumption appears protective against Parkinson's disease with a greater decrease in risk occurring with a larger intake of caffeinated beverages such as coffee. Although tobacco smoke decreases life expectancy and quality of life, it may reduce the risk of PD by a third when compared to non-smokers. The basis for this effect is not known, but possibilities include an effect of nicotine that stimulates the transmittion of signals from neurons to target cells in the brain.
Antioxidants, such as vitamins C and D, have been proposed to protect against the disease but results of studies have been contradictory and no positive effect has been proven. The results regarding fat and fatty acids have been contradictory, with various studies reporting protective effects, risk-increasing effects or no effects. Finally there have been preliminary indications of a possible protective role of estrogens and anti-inflammatory drugs.
Treatment for Parkinson's Disease (PD), due to its chronic nature, requires broad-based management including patient and family education, support group services, general wellness maintenance, exercise, and nutrition. At present, there is no cure for PD, but medications or surgery can provide relief from the symptoms. While many medications treat Parkinson's, none actually reverse the effects of the disease or cure it. Furthermore, the gold standard treatment varies with the disease state. People with Parkinson's therefore often must take a variety of medications to manage the disease's symptoms. Several medications currently in development seek to better address motor fluctuations and nonmotor symptoms of PD. However, none are yet on the market with specific approval to treat Parkinson's.
The main families of drugs useful for treating motor symptoms are Levodopa, dopamine agonists and MAO-B inhibitors.
Treating motor symptoms with surgery was once a common practice, but since the discovery of levodopa, the number of operations declined. Studies in the past few decades have led to great improvements in surgical techniques, so that surgery is again being used in people with advanced PD for whom drug therapy is no longer sufficient. Deep brain stimulation (DBS) is the most commonly used surgical treatment. It involves the implantation of a medical device called a brain pacemaker, which sends electrical impulses to specific parts of the brain. DBS is recommended for people who have PD with motor fluctuations and tremor inadequately controlled by medication, or to those who are intolerant to medication, as long as they do not have severe neuropsychiatric problems.
There is some evidence that speech or mobility problems can improve with rehabilitation. Regular physical exercise can be beneficial to maintain and improve mobility, flexibility, strength, gait speed, and quality of life.
One of the most widely practiced treatments for speech disorders associated with Parkinson's disease is the Lee Silverman voice treatment (LSVT). Speech therapy and specifically LSVT may improve speech. Occupational therapy (OT) aims to promote health and quality of life by helping people with the disease to participate in as many of their daily living activities as possible.
Palliative care (preventing the suffering of patients) is often required in the final stages of the disease when all other treatment strategies have become ineffective. The aim of palliative care is to maximize the quality of life for the person with the disease and those surrounding him or her.
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