Parkinson’s disease is a nervous system disease that affects your ability to control movement. The disease usually starts out slowly and worsens over time. If you have Parkinson’s disease, you may shake, have muscle stiffness, and have trouble walking and maintaining your balance and coordination. As the disease worsens, you may have trouble talking, sleeping, have mental and memory problems, experience behavioral changes and have other symptoms.
About 50% more men than women get Parkinson’s disease. It is most commonly seen in persons 60 years of age and older. However, up to 10% of patients are diagnosed before age 50.
Scientists have discovered gene mutations that are associated with Parkinson’s disease. There is some belief that some cases of early-onset Parkinson’s disease – disease starting before age 50 – may be inherited. Scientists identified a gene mutation in people with Parkinson’s disease whose brains contain Lewy bodies, which are clumps of the protein alpha-synuclein. Scientists are trying to understand the function of this protein and its relationship to genetic mutations that are sometimes seen in Parkinson’s disease and in people with a type of dementia called Lewy body dementia.
Several other gene mutations have been found to play a role in Parkinson’s disease. Mutations in these genes cause abnormal cell functioning, which affects the nerve cells’ ability to release dopamine and causes nerve cell death. Researchers are still trying to discover what causes these genes to mutate in order to understand how gene mutations influence the development of Parkinson’s disease. Scientists think that about 10% to 15% of person’s with Parkinson’s disease may have a genetic mutation that predisposes them to development of the disease. There are also environmental factors involved that are not fully understood.
Parkinson’s disease occurs when nerve cells (neurons) in an area of the brain called the substantia nigra become impaired or die. These cells normally produce dopamine, a chemical (neurotransmitter) that helps the cells of the brain communicate (transmits signals, “messages,” between areas in the brain). When these nerve cells become impaired or die, they produce less dopamine. Dopamine is especially important for the operation of another area of the brain called the basal ganglia. This area of the brain is responsible for organizing the brain’s commands for body movement. The loss of dopamine causes the movement symptoms seen in people with Parkinson’s disease.
People with Parkinson’s disease also lose another neurotransmitter called norepinephrine. This chemical is needed for proper functioning of the sympathetic nervous system. This system controls some of the body’s autonomic functions such as digestion, heart rate, blood pressure and breathing. Loss of norepinephrine causes some of the non-movement-related symptoms of Parkinson’s disease.
Scientists aren’t sure what causes the neurons that produce these neurotransmitter chemicals to die.
Symptoms of Parkinson’s disease and the rate of decline vary widely from person to person. The most common symptoms include:
