Parkinson’s disease

DEFINITION

Parkinson’s disease is a progressive disorder of the nervous system that affects your movement. It develops gradually, sometimes starting with a barely noticeable tremor in just one hand. But while a tremor may be the most well-known sign of Parkinson’s disease, the disorder also commonly causes stiffness or slowing of movement.

In the early stages of Parkinson’s disease, your face may show little or no expression or your arms may not swing when you walk. Your speech may become soft or slurred. Parkinson’s disease symptoms worsen as your condition progresses over time.

Although Parkinson’s disease can’t be cured, medications may markedly improve your symptoms. In occasional cases, your doctor may suggest surgery to regulate certain regions of your brain and improve your symptoms.

CAUSES

In Parkinson’s disease, certain nerve cells (neurons) in the brain gradually break down or die. Many of the symptoms are due to loss of neurons that produce a chemical messenger in your brain called dopamine. When dopamine levels decrease, it causes abnormal brain activity, leading to signs of Parkinson’s disease.

The cause of Parkinson’s disease is unknown, but several factors appear to play a role, including:

• Your genes. Researchers have identified specific genetic mutations that can cause Parkinson’s disease, but these are uncommon except in rare cases with many family members affected by Parkinson’s disease.

  However, certain gene variations appear to increase the risk of Parkinson’s disease but with a relatively small risk of Parkinson’s disease for each of these genetic markers.

• Environmental triggers. Exposure to certain toxins or environmental factors may increase the risk of later Parkinson’s disease, but the risk is relatively small.

  In summary, more research needs to be done to identify the factors causing Parkinson’s disease.

Many changes occur in the brains of people with Parkinson’s disease, including:

• The presence of Lewy bodies. Clumps of specific substances within brain cells are microscopic markers of Parkinson’s disease. These are called Lewy bodies, and researchers believe these Lewy bodies hold an important clue to the cause of Parkinson’s disease.
• A-synuclein is found within Lewy bodies. Although many substances are found within Lewy bodies, scientists believe the most important of these is the natural and widespread protein called alpha-synuclein. It’s found in all Lewy bodies in a clumped form that cells can’t break down. This is currently an important focus among Parkinson’s disease researchers.

SYMPTOMS

Parkinson’s disease symptoms and signs may vary from person to person. Early signs may be mild and may 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.

Parkinson’s signs and symptoms may include:

• Tremor. Your tremor, or shaking, usually begins in a limb, often your hand or fingers. You may notice a back-and-forth rubbing of your thumb and forefinger known as a pill-rolling tremor. One characteristic of Parkinson’s disease is a tremor of your hand when it is relaxed (at rest).
• Slowed movement (bradykinesia). Over time, Parkinson’s disease may reduce your ability to move and slow your movement, making simple tasks difficult and time-consuming. Your steps may become shorter when you walk, or you may find it difficult to get out of a chair. Also, you may drag your feet as you try to walk, making it difficult to move.
• Rigid muscles. Muscle stiffness may occur in any part of your body. The stiff muscles can limit your range of motion and cause you pain.
• Impaired posture and balance. Your posture may become stooped, or you may have balance problems as a result of Parkinson’s disease.
• Loss of automatic movements. In Parkinson’s disease, you may have a decreased ability to perform unconscious movements, including blinking, smiling or swinging your arms when you walk. You may no longer gesture when talking.
• Speech changes. You may have speech problems as a result of Parkinson’s disease. You may speak softly, quickly, slur or hesitate before talking. Your speech may be more of a monotone rather than with the usual inflections. A speech-language pathologist may help improve your speech problems.
• Writing changes. Writing may appear small and become difficult.

Medications may greatly reduce many of these symptoms. These medications increase or substitute for dopamine, a specific signaling chemical (neurotransmitter) in your brain. People with Parkinson’s disease have low brain dopamine concentrations.

When to see a doctor

See your doctor if you have any of the symptoms associated with Parkinson’s disease — not only to diagnose your condition but also to rule out other causes for your symptoms.