Parkinson’s disease (PD) is an age-related progressive deterioration of certain nerve systems in the brain which affects movement, balance, and muscle control.
Parkinson’s disease is one of the most common movement disorders, affecting about 1% of the population over 60 years of age. Parkinson’s disease is about 1.5X more common in men than in women, and it becomes more likely to occur in people as they age.
The average age of onset is about 60 years old; onset before the age of 40 is relatively uncommon.
In Parkinson’s disease, brain cells deteriorate (or degenerate) in an area of the brain called the substantia nigra. From the substantia nigra, specific nerve cell tracts connect to another part of the brain called the corpus striatum, where the neurotransmitter (a chemical messenger in the brain) called dopamine is released. Dopamine is an important neurotransmitter and alterations in its concentration can lead to the different medical problems seen in Parkinson’s disease.
The loss of these specific brain cells and decline in dopamine concentration are key steps that lead to the signs and symptoms of Parkinson’s disease as well as are the target for treatments of Parkinson’s disease. However, the biological, chemical, and genetic mechanisms responsible for the brain cell loss have not been identified with certainty.
Symptoms
Parkinson’s disease signs and symptoms can be different for everyone. Early signs may be mild and go unnoticed. Symptoms often begin on one side of the body and usually remain worse on that side, even after symptoms begin to affect both sides.
Tremor
A tremor, or shaking, usually begins in a limb, often the hand or fingers. A person may rub their thumb and forefinger back-and-forth, known as a pill-rolling tremor. The hand may tremor when it’s at rest.
Slowed movement (Bradykinesia)
Over time, Parkinson’s disease may slow movement, making simple tasks difficult and time-consuming. Steps may become shorter when walking. It may be difficult to get out of a chair and feet may drag when walking.
Stiffness
Muscle stiffness may occur in any part of the body. The stiff muscles can be painful and limit the range of motion.
Other Symptoms may include
sleep, digestion (constipation is common), speech, difficulty writing, mood changes, swallowing, thinking, and memory.
Diagnosis of Parkinson’s Disease
A number of disorders can cause symptoms similar to those of Parkinson’s disease. People with Parkinson’s-like symptoms that result from other causes are sometimes said to have parkinsonism. While these disorders initially may be misdiagnosed as Parkinson’s, certain medical tests, as well as response to drug treatment, may help to distinguish them from Parkinson’s. Since many other diseases have similar features but require different treatments, it is important to receive an exact diagnosis as soon as possible.
Treatment
Medications
- Drugs that increase the level of dopamine in the brain
- Drugs that affect other brain chemicals in the body
- Drugs that help control nonmotor symptoms
The main therapy for Parkinson’s is levodopa, also called L-dopa. Nerve cells use levodopa to make dopamine to replenish the brain’s dwindling supply. Usually, people take levodopa along with another medication called carbidopa. Carbidopa prevents or reduces some of the side effects of levodopa therapy—such as nausea, vomiting, low blood pressure, and restlessness—and reduces the amount of levodopa needed to improve symptoms.
Individuals with Parkinson’s should never stop taking levodopa without telling their doctor. Suddenly stopping the drug may have serious side effects, such as being unable to move or having difficulty breathing.
Other medicines used to treat Parkinson’s symptoms include:
- Dopamine agonists to mimic the role of dopamine in the brain
- MAO-B inhibitors to slow down an enzyme that breaks down dopamine in the brain
- COMT inhibitors to help break down dopamine
- Amantadine, an old antiviral drug, to reduce involuntary movements
- Anticholinergic drugs to reduce tremors and muscle rigidity
Deep Brain Stimulation (DBS)
For individuals with Parkinson’s who do not respond well to medications, DBS, may be appropriate. DBS is a surgical procedure that surgically implants electrodes into part of the brain and connects them to a small electrical device implanted in the chest. The device and electrodes painlessly stimulate the brain in a way that helps stop many of the movement-related symptoms of Parkinson’s disease.
Additional Therapies
Additional therapies may be used to help with Parkinson’s disease symptoms. They include physical, occupational, and speech therapies, which help with gait and voice disorders, tremors and rigidity, and decline in mental functions. Other supportive therapies include a healthy diet and exercises to strengthen muscles and improve balance.