Aging & Health A to Z
Causes & Symptoms
Parkinson’s disease is caused by damage to a special kind of nerve cells (neurons), that produce a chemical called dopamine. Dopamine sends messages throughout the body. Most of these dopamine-producing neurons are in a part of the brain called the substantia nigra, which plays a key role in movement. But some are in other parts if the body that play other roles.
In people with Parkinson’s, the special neurons produce less and less dopamine. As a result, controlling movement and carrying out other tasks gets increasingly difficult. Automatic activities carried out by the body’s autonomic nervous system (such as digestion and regulation of blood pressure) may be affected by the disease. Among other things, Parkinson’s can also affect mood, sleep, thinking, and memory.
Parkinson’s disease is more common with increasing age. In the United States, it is most common among people in their 70s and 80s. Roughly one of every 500 adults in this age group has Parkinson’s.
The disease is also more common in men than women—one and a half times more common. People with a parent, sister or brother with Parkinson’s disease are up to 10% percent more likely to develop it than people with no family history of the disease.
People who were exposed, for long periods of time, to certain pesticides and chemicals used to kill weeds and fungus, also run a higher risk of developing Parkinson’s disease than others. So do people who have had long-term exposure to high levels of a mineral called manganese, such as steel workers.
Parkinson’s disease is primarily a movement (motor) disorder that causes movement symptoms. But it can also cause “non-motor” symptoms, such as changes in mood.
It’s important to remember that different people can have different symptoms of Parkinson’s. Early on, symptoms are usually very mild. They tend to get worse and more noticeable over the course of years. As they get worse, symptoms of the disease make activities of daily living (such as dressing and feeding yourself) increasingly difficult.
Common Movement Problems
Movement problems are the most common symptoms of Parkinson’s. Early on, movement problems usually affect only one side of the body, often with shakiness (tremors), stiffness, or problems with coordination. Over time, symptoms tend to get more severe and may affect the other side of the body as well—but the symptoms on that side are usually milder than those on the side affected first.
The four main movement problems of Parkinson’s disease are:
- tremors (shaking)
- difficulty with balance (postural instability)
- slowed movements (bradykinesia)
- stiffness (muscular rigidity).
Tremors are the most common symptom of Parkinson’s. Most, but not all, people with the disease develop tremors. Tremors are shaking or back-and-forth movements that usually start in the hands but can start in the feet. Sometimes, the tremors involve only the thumb and pointer finger, which move back and forth in a rubbing motion, as though the person is rolling a small object between these fingers.
These tremors are called “resting tremors” because they usually occur when the muscles are at rest, rather than when the person with the disease is using the muscles. The tremors may get worse when the person is under stress. They usually stop when the person deliberately moves the part of the body that is shaking, and when he or she is asleep. In some people, the jaw, head, legs, or arms are affected by resting tremors. Mostly these tremors are noticeable and a reason people will seek medical attention, but usually they do not cause problems in functioning as much as the other symptoms of Parkinson's disease do.
Postural instability is poor balance, and makes it difficult for people with Parkinson’s to get into and stay in a standing or sitting position. People with the disease tend to sway backward or forward and run an increased risk of falling.
Slowed movements (Bradykinesia)
Bradykinesia is a slowing and loss of both voluntary and “automatic” muscle movements. This makes simple activities, such as buttoning a shirt or brushing teeth, increasingly difficult and time-consuming. People with bradykenisia take longer to start and complete movements. They may shuffle their feet when walking. They may have difficulty getting the words out when they speak and especially starting a sentence. The problems with slowed movements may also increase risks of falling. When you’re about to lose your balance, you usually take a step forward or back, or put your arms out to brace yourself --but people with bradykinesia have difficulty making these movements quickly enough.
Stiffness (Muscular rigidity)
Stiffness affects most people with Parkinson’s. The muscles in their arms, legs, neck, and trunk remain tensed or “contracted,” causing discomfort, resistance in moving, and requires more effort to move. This stiffness can limit their “range of motion” -- how far they can move these parts of their bodies.
Other movement symptoms of Parkinson’s include:
- Start hesitation – difficulty starting or initiating movement. A person with this symptom will have difficulty taking a first step, for example, but is usually able to walk normally once he or she takes that first step.
- Freezing – suddenly stopping while walking or making other movements
- Very rapid movements – some people with Parkinson’s tend to lean forward and shuffle as they walk, gaining speed as they go with inability to slow down. They are at high risk of falling.
- Speech problems – Parkinson’s can affect the muscles in the voice box or (larynx) and make speaking difficulty. People with the disease may slur their words or stammer so quickly that they are hard to understand. Others may speak very softly, talk in a monotone (flat-sounding), or hesitate.
- Difficulty feeding oneself or chewing and swallowing food, which can increase risks of choking and contribute to poor nutrition
- Gradual shrinking in the size of one’s handwriting, which also gets more cramped and difficult to read
- A mask-like facial expression
Common Non-Movement Symptoms
- Changes in mood – a person with Parkinson’s may show signs of depression, anxiety, irritability or other changes in mood.
- Bladder problems and constipation – because the disease affects the nerves involved in the bowels and bladder, people with Parkinson’s may have difficulty controlling their bladders, or, on the other hand, may have difficulty urinating. The disease can also contribute to constipation. People often get less exercise, and drink less, as the disease progresses, and these things can make constipation even worse, as can certain medications prescribed to treat the disease.
- Sexual problems – changes in blood pressure that can accompany Parkinson’s may make it difficult for men to have erections.
- Dizziness and faintness – Parkinson’s can affect blood pressure, which may drop suddenly when a person with the disease stands up from a lying-down position. This drop in blood pressure is called orthostatic hypotension and can cause dizziness or fainting. Certain medications for Parkinson’s can also cause low blood pressure.
- Difficulty thinking and remembering – some, but not all, people with Parkinson’s develop thinking and memory problems.
- Sleep problems and fatigue – people with the disease may have difficulty staying asleep after they fall asleep. They may also have restless sleep and difficulty getting comfortable in bed. As a result, they may feel drowsy during the day.
People taking prescription medications for Parkinson’s disease should not take over-the-counter (OTC) sleeping medications without first checking with their healthcare professional. Parkinson’s medications can interact with OTC sleep medications in dangerous ways.
Disorders Similar to Parkinson’s Disease
It is possible to have symptoms similar to Parkinson's disease that are caused by other things; this is known as "Parkinsonism". Healthcare professionals distinguish these disorders from one another and from Parkinson’s disease based on their differing symptoms. These conditions include: Progressive supranuclear palsy, multiple system atrophy, and movement disorders caused by drugs.
Progressive Supranuclear Palsy
Like Parkinson’s disease, progressive supranuclear palsy slows movements and causes tremors, but this disorder usually progresses much faster than Parkinson’s does. Supranuclear palsy can cause significant disability within just a few years.
Among other things, a person with progressive supranuclear palsy tends to fall often, even early in the course of the disease, and very often fall going down stairs. He or she may also develop difficulty moving his or her facial muscles, tongue and mouth, and have problems swallowing and speaking, early on.
With Parkinson’s disease, muscle stiffness usually starts in the arms and legs and then spreads to the rest of the body. But with progressive supranuclear palsy, stiffness typically begins in the body and then spreads to the arms and legs.
People with progressive supranuclear palsy also have difficulty moving their eyes up and down, and, later, from side to side. While people with Parkinson's disease may have some difficulty moving their eyes, their eye movements are much less limited than those of people with progressive supranuclear palsy. People with the disorder may show emotional and personality changes as well.
Multiple System Atrophy
Multiple system atrophy (MSA) refers to a group of Parkinsonian syndromes and is sometimes known as “Parkinson’s plus.” These syndromes cause both symptoms that are similar to Parkinson’s symptoms (such as tumors, rigidity, bradykinesia, and postural instability) and additional symptoms due to changes in the autonomic nervous system. The latter include light headedness, fainting spells, constipation, difficulty urinating, and erectile dysfunction. In addition, people with MSA may be unsteady on their feet, and have limited vision and other vision problems.
Movement Problems Caused by Drugs
Several drugs used to treat psychiatric disorders can cause movement problems in older adults. The type of medication, the dose of the drug, and the length of time the person has been taking it, usually determine how severe the movement problem is.
Among people who have only been taking antipsychotic drugs for a short time, the symptoms usually disappear shortly after the drugs are stopped but at times may not fully go away. Among those who have taken high doses of these drugs for long periods, however, symptoms a likely to be irreversible. Long-term treatment with antipsychotic drugs can sometimes cause extreme restlessness, an inability to remain still, and sudden muscle movements. People with these symptoms usually complain of severe stiffness, cramps and other pains.
Tardive dyskinesia is a severe movement disorder that can develop after months or years of taking antipsychotic drugs. It causes rapid, irregular muscle contractions that cause the person's lips, tongue, face, and neck to move constantly.
Updated: March 2012
Posted: March 2012