Nicholas R. Metrus, MD, is a board-certified neurologist and neuro-oncologist. He currently serves at the Glasser Brain Tumor Center in Summit, New Jersey.
Parkinson's disease is a progressive neurodegenerative disorder that develops when brain cells that produce dopamine die.
Dopamine is a vital chemical messenger (neurotransmitter) that helps regulate movement. When dopamine is depleted, classic Parkinson's symptoms like slowness of movement, shaking, stiffness, and walking difficulties can occur.
Doctors used to consider Parkinson's disease solely a motor (movement) disorder, but now they know it also causes non-motor-related symptoms like sleep problems, anxiety, loss of smell, and constipation, and that these symptoms may actually predate the motor symptoms by many years or even decades.
Experts haven’t pinned down the exact cause, but it’s believed that Parkinson’s is caused by certain genes and environmental factors, like exposure to toxins. This leads to brain changes, which may play causal roles. They are:
It’s believed to be, at least in part. Experts don’t know the exact cause(s) yet, but they believe Parkinson’s disease may be caused by a complex interaction between your genes and your environment, which may include toxins like pesticides. Only about 14% of people with the disease have a first-degree relative with Parkinson’s. Risk factors include being over age 60 and being biologically male.
The earliest symptoms of Parkinson’s disease are often non-motor symptoms, including:
These symptoms result from neurological changes that will eventually lead to classic Parkinson’s symptoms like tremor, slowness and other movement problems.
Parkinson’s progresses through these stages over time:
Treatment can prevent progression to later stages.
Thus far, there’s no known way to prevent Parkinson’s disease. Genetic testing can tell you your risk, which may help with earlier diagnosis and treatment. That, in turn, may slow the progression of the disease. However, it’s not yet possible to prevent the disease from developing.
Parkinson’s disease currently has no known cure. However, a number of treatments can ease the symptoms and researchers are always learning more about how to possibly slow down the progression of the disease.
Alpha-synuclein is a protein in the human brain that’s involved in the release of dopamine, an important neurotransmitter. In Parkinson’s disease, alpha-synuclein is abnormally folded, which causes it to clump up in dopamine-producing neurons and form a mass called a Lewy body. Lewy bodies destroy neurons, leading to dopamine deficiency and symptoms of Parkinson’s.
Bradykinesia is the term for the distinctive slow movements of people with Parkinson’s disease. It is the cardinal symptom of the disease and necessary for the diagnosis. Along with tremors and muscle rigidity, it’s one of the three core symptoms experienced by everyone with the disease. Bradykinesia can cause a shuffling kind of walk, slow speech, and difficulty with fine motor control.
Dopamine is a neurotransmitter, meaning it’s a special substance that transmits chemical messages from one neuron (brain or nerve cell) to another. Dopamine is highly involved with how your body moves. In Parkinson’s disease, the cells that produce dopamine die, leading to dopamine deficiency. This leads to symptoms such as tremors, impaired balance, and slow movement.
Lewy bodies are abnormal clumps that form in brain cells that produce the neurotransmitter dopamine. They’re toxic and mainly made up of a protein called alpha-synuclein. Lewy bodies kill the dopamine-producing cells, which leads to dopamine depletion and causes Parkinson’s symptoms. Lewy bodies can cause two types of dementia: dementia with Lewy bodies and Parkinson’s dementia.
Neurological disorders are medical conditions involving dysfunction of the brain and nerves. They’re typically treated by neurologists. Common neurological disorders include Parkinson’s disease, Alzheimer’s disease, stroke, multiple sclerosis, epilepsy.
Neurons are nerve or brain cells. While they’re largely similar to other cells throughout your body, neurons have the specialized ability to transmit signals around your body and brain. They do this by releasing chemical messengers (neurotransmitters) into the gaps between themselves and neighboring cells. Parkinson’s disease involves low levels of the neurotransmitter dopamine.
A tremor is an involuntary shaking or quivering movement. Many types of tremor exist. Parkinson’s disease involves a resting tremor, which is most noticeable when the shaking body part is at rest and diminishes with movement. Some people have a Parkinsonian tremor without having Parkinson’s disease. Another common type is essential tremor, which occurs when the body part is being used.
National Institute on Aging. Parkinson's disease. May 16, 2017.
World Health Organization. What are neurological disorders? May 3, 2016.
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