Aging & Health A to Z
Causes & Symptoms
Parkinson’s disease is caused by damage to a special kind of nerve cells (neurons) in a specific part of the brain that produce a chemical called dopamine. Dopamine sends messages throughout the body that help control movement. In people with Parkinson’s, these neurons produce less and less dopamine. As a result, controlling movement and carrying out other tasks gets increasingly difficult. The cause of the damage to these neurons is not known.
The strongest risk factors for Parkinson’s disease are age and family history.
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 in every 500 adults in this age group has Parkinson’s. About 10-15% of people with Parkinson’s disease have a parent or sibling who also has the disease. Some studies have reported that Parkinson’s disease is more common in men than in women, but other studies have not shown this.
People with long periods of exposure to pesticides also have a higher risk of developing Parkinson’s disease.
The most obvious symptoms of Parkinson’s disease are those that affect movement, called “motor” symptoms. However, Parkinson’s disease can also cause symptoms that are not related to movement. These are called “non-motor” symptoms.
It’s important to remember that different people can have different symptoms of Parkinson’s. Early on, symptoms are usually very mild, but tend to get worse and more noticeable over the course of years. As symptoms worsen, activities of daily living (such as dressing and feeding yourself) may become increasingly difficult.
Motor symptoms, those symptoms that affect movement, are the most common symptoms of Parkinson’s. Early on, movement problems usually affect only one side of the body. 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 motor symptoms of Parkinson’s disease are:
- Tremor (shaking)
- Bradykinesia (slowed movements)
- Rigidity (muscle stiffness)
- Postural instability (difficulty with balance)
Tremors (shaking) affect most people with Parkinson’s disease at some point. Early on, the tremor may not be noticeable. The tremor caused by Parkinson disease usually starts in one hand and is often described as “pill-rolling”. Over several years, the tremor usually spreads to the other side of the body, but remains worse on the side on which it started. The tremor of Parkinson’s disease is a resting tremor, meaning that the tremor is there when the muscles are at rest, but goes away when the person deliberately moves the part of the body that is shaking. Tremors may get worse with stress or anxiety.
Bradykinesia is slowness of movement. Bradykinesia eventually affects everyone with Parkinson’s disease, and may cause feelings of fatigue and weakness. People with bradykinesia take longer to start and complete movements, which can make simple activities increasingly difficult and time-consuming. Bradykinesia can make it difficult to button a shirt, brush your teeth, or type. People with bradykinesia may have difficulty starting a sentence and getting words out when they speak. In the legs, bradykinesia can cause people to take short, shuffling steps, and to have difficulty quickly adjusting to a loss of balance, increasing the risk for falling.
Rigidity causes muscles in the arms, legs, or torso to be stiffened. This causes discomfort and difficulty moving. Rigidity can limit range of motion, for example, how far someone can extend their arm. Like other motor symptoms of Parkinson’s disease, rigidity usually starts on the same side of the body as the other symptoms, and gradually affects the other side over time.
Postural instability is poor balance. In Parkinson’s disease, automatic reflexes in the brain that help us stay balanced start to fail. This 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 are at increased risk of falling. Loss of balance and falling usually occur later in the disease. Some people eventually need assistance or a wheelchair to move around.
Other motor symptoms of Parkinson’s disease include:
- Short, shuffling steps
- Freezing – suddenly stopping while walking or making other movements
- Festination – short shuffling steps that become faster
- Speech problems – soft, flat-sounding speech, slurred speech, stammering
- Swallowing problems – difficulty chewing or swallowing food, excessive saliva or drooling
- Micrographia – gradual shrinking in the size of handwriting, making it cramped and difficult to read
- Visual changes – decreased eye blinking, blurred vision
- Hypomimia – loss of facial expression, sometimes called a “ mask-like” facial expression
Parkinson’s disease can also cause symptoms that are not related to movement, but can be bothersome. Some common non-motor symptoms include:
- Changes in memory and thinking. These occur in about 40% of people with Parkinson’s disease and may include problems with decision making, short-term memory, and multi-tasking. These cognitive problems may be mild or severe. Some people with Parkinson’s disease develop dementia, which is when problems with memory and thinking are serious enough to affect daily activities. Sometimes, people may have hallucinations or delusions with paranoia, such as believing someone is stealing from them, their spouse is cheating on them, or someone is trying to harm them.
- Changes in mood. People with Parkinson’s may experience depression, anxiety, irritability or other changes in mood. Some people have a loss of motivation, called apathy, which can cause decreases in speech, emotion, and activity.
- Sleep problems. People with Parkinson’s disease may have difficulty falling and staying asleep. Sleep problems may be because of difficulty turning over in bed and getting comfortable, or because of vivid dreams or the need to urinate frequently. Some people can have a sleep disorder that causes them to act out their dreams.
- Fatigue. Daytime sleepiness is common in people with Parkinson’s disease. Some people experience sudden “sleep attacks”. These symptoms are important to tell your doctor about, as they can affect your safety with activities such as driving.
- Autonomic dysfunction. Parkinson’s disease can affect the control of many automatic functions in the body. This can cause symptoms such as a drop in blood pressure when standing up (leading to dizziness or lightheadedness), constipation, urinary leakage or difficulty urinating, and sexual dysfunction (abnormally decreased or increased interest in sex or difficulty having erections for men).
- Loss of smell. Many people with Parkinson’s disease lose the ability to detect or identify odors. This often happens early in the disease.
- Pain. People with Parkinson’s disease may experience pain in several places or only in specific areas, often in the same parts of the body affected by the motor symptoms. The pain can be sharp, stabbing, burning, or tingling.
There are several rare disorders that have symptoms similar to Parkinson's disease, but have different causes and unique features. The most common of the Parkinson-Plus Syndromes include:
- Progressive Supranuclear Palsy (PSP)
Like Parkinson’s disease, people with PSP have motor symptoms such as muscles stiffness and problems with balance. People with PSP tend to have more difficulty with balance and walking early in the disease, and tend to fall often. PSP also affects the movement of the eyes, up and down and side-to-side. Problems with speech and swallowing are often more severe in PSP. PSP usually progresses much faster than Parkinson’s does, and can cause significant disability within just a few years.
- Multiple System Atrophy (MSA)
Multiple system atrophy (MSA) refers to a group of disorders that share many features with Parkinson’s disease. In addition to problems with muscle stiffness, balance and slowed movement, people with MSA often have problems with coordination and tend to fall early in the disease. Problems with urination, erectile dysfunction in men, and low blood pressure are also common in MSA, but problems with memory and thinking are less common than in Parkinson’s disease.
- Cortiobasal Degeneration
Corticobasilar degeneration is a rare disorder that causes certain areas of the brain to degenerate, or shrink, over time. Like Parkinson’s disease, people with corticobasal degeneration have motor symptoms initially on one side, which then spreads to both sides. Problems with thinking and personality or behavior changes often occur early in the disease.
- Drug-Induced Parkinsonism Some medications can cause the kind of movement problems seen in Parkinson’s disease. The most common of these are antipsychotic medications, which are used to treat some serious psychiatric disorders, and anti-nausea medications. Usually the Parkinson-like symptoms will go away once the drug is stopped. If you have concerns about your medications, talk to your healthcare provider. Never stop a medication without talking to your healthcare provider.
Updated: March 2017
Posted: March 2012