Parkinson's disease (PD)

            Description of the disease: Parkinson's disease (PD) is a progressive disorder that affects movement, muscle control, and balance. Usually, the first symptom of Parkinson's disease is trembling or shaking of a limb, especially when the body is at rest. The tremor often begins on one side of the body, frequently in one hand. Other common symptoms include slow movement (bradykinesia), an inability to move (akinesia), rigid limbs, a shuffling gait, and a stooped posture. People with Parkinson's disease often have reduced facial expressions and speak in a soft voice. The severity of Parkinson's symptoms tends to worsen over time. Parkinson's disease is referred to as idiopathic, which means that the cause is unknown. This term distinguishes the primary disease from Parkinsonism, which are the symptoms occurring from a known cause. .
             What is cause: The cause of Parkinson's disease is unknown. Although it is clear that dopamine deficiency is the primary defect in Parkinson's disease, it is not clear what causes dopamine loss. There is also destruction of nerve cells in a part of the brain called the basal ganglia. The likely cause is probably a combination of genetic and biological factors, which are triggered by some environmental assault. Exposure to an environmental toxin, such as a pesticide, that inhibits dopamine production and produces free radicals and oxidation damage may be involved. Genetic factor may be involved because roughly one-fifth of Parkinson's disease patients have at least one relative with parkinsonian symptoms.
             Risk Factors: The number of people in the United States with Parkinson's range from 500,000 to 1,500,000 with 50,000 new cases reported annually. The average age of onset is about 60, increase with advancing age; the rates are very low in people under 40 and rise among people above 70 and 80. Although PD is more common in older persons, it is rare in people younger than 30 but some people do begin to show symptoms before they are 40 years old and risk increases with age.