Parkinson's Disease

Parkinson's disease (PD) is a progressive disorder of the nervous system that affects movement. PD occurs when small clusters of neurons in the brain die. The gradual loss of these neurons results in reduction of a critical neurotransmitter dopamine - a chemical responsible for transmitting messages to parts of the brain that coordinate muscle movement. Symptoms of PD appear when at least half of the dopamine neurons in the brain have died.

PD develops gradually, sometimes starting with a barely noticeable tremor in just one hand, which is the most well-known sign of PD. The disorder also commonly causes stiffness or slowing of movement.

In the early stages of PD, the face may show little or no expression or the arms may not swing when you walk. Speech may become soft or slurred. PD symptoms worsen as the condition progresses over time.

PD cannot be cured, but medications may improve the symptoms. Rarely, surgery to regulate certain regions of the brain may help improve symptoms.

PD symptoms and signs may vary from person to person. Early signs may be mild and go unnoticed. Symptoms often begin on one side of your body and usually remain worse on that side, even after symptoms begin to affect both sides. Symptoms of PD typically worsen over time.

Common motor symptoms include:

• tremors or shaking in hands, arms, legs, jaw, and face
• rigidity or stiffness of limbs and trunk
• slowness of movement
• difficulties with balance, speech, and coordination
• impaired posture and balance
• loss of automatic or unconscious movements, such as blinking, smiling, or swinging your arms when you walk
• changes in handwriting

Nonmotor symptoms may develop years before the onset of motor problems. These may include:

• poor sense of smell
• constipation
• depression
• cognitive impairment
• fatigue

The exact cause of PD is unknown, though most researchers agree that the disease is caused by both genetic and environmental factors, as well as the interactions between the two. Mutations in certain genes seem to increase the risk of PD, but these alterations are rare. Exposure to certain toxins or foods also increases the risk of PD, but the risk is still relatively small. Head injuries may also contribute to the development of PD.

No specific test can diagnose PD. A doctor trained in nervous system conditions (a neurologist) will diagnose PD on the basis of your medical history, your signs and symptoms, and a neurological and physical examination.

Blood tests may be conducted to rule out other conditions that may be causing your symptoms.

Imaging tests, such as magnetic resonance imaging, ultrasound of the brain, and positron emission tomography scans, may also be used to help rule out other disorders.

Your doctor may also give you carbidopa-levodopa, a medication for PD. Significant improvement of your symptoms with this medication will often confirm your diagnosis of PD.

If you have PD, work closely with your doctor to find a treatment plan that offers you the greatest relief from symptoms with the fewest side effects. Certain lifestyle changes may also help make living with PD easier.

• Eat healthy. No foods or combination of foods are proven to help in PD, but some foods may help ease some of the symptoms. For example, eating foods high in fiber and drinking an adequate amount of fluids can help prevent constipation that is common in PD. A balanced diet also provides nutrients, such as omega-3 fatty acids, that may be beneficial for people with PD.
• Exercise. Exercising may increase your muscle strength, flexibility, and balance. Exercise can also improve your well-being and reduce depression or anxiety. PD can disturb your sense of balance, making it difficult to walk with a normal gait, and exercise may improve your balance.
• Avoid falls. In the later stages of the disease, you may fall more easily. In fact, you may be thrown off balance by just a small push or bump. Take care to stay safe and avoid falls. Assistive devices may help to maintain your balance, as well as your independence.
• Practice activities of daily living. Daily living activities such as dressing, eating, bathing, and writing can be difficult for people with PD. An occupational therapist can show you techniques that make daily life easier.

PD cannot be cured, but medications can help control your symptoms, often dramatically. In some later cases, surgery or deep brain stimulation (DBS) may be advised. With DBS, electrodes are surgically implanted in the brain. They send electrical pulses to stimulate the parts of the brain that control movement.

Medications may help you manage problems with walking, movement, and tremor. These medications increase or substitute for dopamine, the signaling chemical (neurotransmitter) in your brain that is lost with PD.

Medications for PD include:

• Carbidopa-levodopa. Levodopa is the most effective PD medication. It is a natural chemical that passes into your brain and is converted to dopamine. Levodopa is combined with carbidopa (Rytary, Sinemet), which protects levodopa from premature conversion to dopamine outside your brain; this prevents or lessens side effects such as nausea. In 2015, The U.S. Food and Drug administration approved a drug called Duopa. This medication is made up of carbidopa and levodopa and is administered through a feeding tube that delivers the medication in a gel form directly to the small intestine. Duopa is for patients with more advanced PD who still respond to carbidopa-levodopa but who have fluctuations in their response.
• Dopamine agonists. Unlike levodopa, dopamine agonists do not change into dopamine. Instead, they mimic dopamine effects in your brain. They are not as effective as levodopa in treating your symptoms, but they last longer and may be used with levodopa to smooth the off-and-on effects of levodopa. Dopamine agonists include pramipexole (Mirapex), ropinirole (Requip), and rotigotine (Neupro). A short-acting injectable dopamine agonist, apomorphine (Apokyn) is used for quick relief of symptoms.
• MAO-B inhibitors. These medications help prevent the breakdown of brain dopamine by inhibiting the brain enzyme monoamine oxidase B (MAO-B), which metabolizes dopamine. Examples include selegiline (Eldepryl, Zelapar) and rasagiline (Azilect).
• Catechol-O-methyltransferase (COMT) inhibitors. Entacapone (Comtan) is the primary medication from this class. This medication mildly prolongs the effect of levodopa therapy by blocking an enzyme that breaks down dopamine.
• Amantadine. Doctors may prescribe amantadine (Symmetrel) alone to provide short-term relief of symptoms of mild, early-stage PD. It may also be given with carbidopa-levodopa therapy during the later stages of PD to control involuntary movements (dyskinesias) induced by carbidopa-levodopa.