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PARKINSON DISEASE OVERVIEW — Parkinson disease (PD) is a common disorder that affects the brain's ability to control movement. More than 1 million people in North America have been diagnosed with PD, most of whom are greater than 60 years old. PD progressively worsens over time, although the rate of worsening varies greatly from one person to another. Many people with PD who are treated may be able to live years without serious disability. A number of treatments are available that can help to manage symptoms and improve quality of life.
This topic review discusses the causes, symptoms, and diagnosis of PD. Separate topic reviews are available that discuss treatment. (See "Patient education: Parkinson disease treatment options — medications (Beyond the Basics)" and "Patient education: Parkinson disease treatment options — education, support, and therapy (Beyond the Basics)".)
PARKINSON DISEASE CAUSE — The cause of PD is not known. Normally, certain nerve cells (neurons) in the brain make a chemical called dopamine, which helps to control movement. In people with PD, these neurons slowly degenerate and lose their ability to produce dopamine. As a result, the symptoms of PD develop gradually and tend to become more severe over time. It is not clear how or why these neurons stop working correctly.
Approximately 10 to 15 percent of people with PD have at least one first-degree relative (parent or sibling) with the disease. The disease seems to be passed down from family members in only a small number of cases. In younger people (those diagnosed before age 50), genetic mutations may play a role. Most movement disorder specialists think that PD is due to a complex combination of genes and environmental causes.
PD is more common in people over age 50, and approximately 1 percent of people over age 60 are estimated to have PD. More men than women appear to have PD, although further studies are needed to confirm this.
PARKINSON DISEASE SYMPTOMS — The signs and symptoms of PD can be divided into two categories: motor and nonmotor.
Motor symptoms — Motor symptoms are those that affect movement of the body. These are the most obvious symptoms of PD. The main motor symptoms of PD are tremor, slowness of movement (called bradykinesia), stiffness (rigidity), and poor balance (postural instability). These symptoms are usually mild in the early stages of the disease.
Symptoms typically start on one side of the body and spread to the other side over a few years. As symptoms worsen, a person may have difficulty with walking, talking, and performing other normal daily tasks. While symptoms typically progress slowly, this varies from one person to another. It is important to discuss any bothersome or worsening symptoms with a healthcare provider so that the optimal type of treatment can be given. The symptoms of PD can be managed effectively for a significant period of time.
Tremor — Tremors (shaking) caused by PD are most noticeable when the affected body part is at rest. The tremor of early PD is intermittent and may not be noticeable to others; some people report a feeling of "internal shakiness" in the limbs or body that cannot be seen. When the tremor becomes noticeable, it usually occurs in one hand, often described as "pill-rolling." The tremor usually spreads to the other side of the body over a period of a few years. Anxiety, excitement, and stress can worsen the tremor. Other body parts may be affected by the tremor, including the legs, lips, jaw, or tongue. However, the tremor of PD usually does not affect the head.
The majority of people with PD will notice a tremor at some point in the disease, though some do not. The side of the body that is first affected by the tremor also tends to be more severely affected throughout the course of the disease.
Bradykinesia — Bradykinesia is a generalized slowness of movement. It eventually affects everyone with PD, and may result in feelings of incoordination, weakness, or tiredness.
In the arms, bradykinesia can cause difficulty with tasks such as buttoning clothes, tying shoelaces, double clicking a computer mouse, typing, or lifting coins from a pocket or purse. Bradykinesia may cause a person to drag the legs when walking; take shorter, shuffling steps; or have a feeling of unsteadiness. A person may also have difficulty standing up from a chair or getting out of a car.
As the disease progresses, the person may suddenly "freeze up" or take much quicker and shorter steps while walking (called festination).
Rigidity — Rigidity causes stiffened movement of the arms, legs, or body. It usually begins on the same side of the body as other early symptoms, such as tremor and bradykinesia. As the disease progresses, both sides of the body are affected.
Poor balance (postural instability) — Normally, there are automatic reflexes in the brain that help us to remain balanced when we stand or walk. In people with PD, these reflexes fail, causing a tendency to fall or to feel off balance. Loss of balance and falling, known as postural instability, usually do not occur until later in the course of PD. As these reflexes stop working, the person will have more and more trouble with walking, to the point where some may need assistance or need a wheelchair to get around.
If postural instability develops early in the course of the disease, this suggests a parkinsonian syndrome other than PD, such as progressive supranuclear palsy or multiple system atrophy.
Other motor features — There are a number of other motor-related signs and symptoms of PD. These are listed in the table (table 1).
Nonmotor symptoms — Nonmotor symptoms of PD are those that are not related to movement. Many nonmotor symptoms affect the person's mood, senses (eg, smell, taste, sight), and ability to think (table 2). Some of the most bothersome nonmotor symptoms of PD will be discussed here.
Cognitive problems and dementia — Problems with thinking and memory commonly occur in PD and can range from mild to severe. Some studies indicate that 40 percent or more of people with PD are affected with these problems over the long term. Common cognitive symptoms include taking longer to process information and difficulty making decisions, multitasking, remembering recent events, and judging distances.
Psychosis and hallucinations — Psychosis is defined as a disorder of thinking that causes the person to lose touch with reality. Psychotic symptoms occur in 20 to 40 percent of people treated with medications for PD. The underlying cause of psychosis is poorly understood, although many medications used to treat PD can cause psychosis as a side effect, particularly in a person who already has cognitive problems. Visual hallucinations (seeing things that are not real) are the most common symptoms of psychosis in people with PD, and these usually become more frequent and severe as PD progresses.
Hallucinations may be accompanied by delusions, usually with paranoid overtones, such as irrational fears that a spouse is cheating, money is being stolen, intruders are living in the house, or caretakers are plotting harm. Many, although not all, people with PD who have psychotic symptoms are aware, or can be convinced, that their delusional thoughts are not based in reality. However, delusional thinking can be so intense that it has a serious impact on behavior, leading the affected person to call the police for imagined threats.
Mood disorders — Depression, anxiety, and loss of motivation (apathy) are common mood disorders in people with PD. All of these conditions can significantly decrease a person's quality of life and worsen motor symptoms.
●Symptoms of depression in PD usually include sadness, loss of the ability to experience pleasure, and decreased interest in activities.
●Symptoms of anxiety may include panic attacks, excessive worry, or fear.
●Apathy is defined as a loss of motivation leading to diminished speech, movement, and emotional expression.
Treatment of these problems is discussed separately. (See "Patient education: Depression treatment options for adults (Beyond the Basics)".)
Sleep disorders — Difficulties falling asleep and staying asleep are common problems for many people with PD. These problems may be related to wearing off of PD medications (leading to tremor, difficulty turning over in bed, muscle cramps, or pain), vivid dreams or nightmares, or needing to urinate frequently.
A disorder known as rapid eye movement (REM) sleep behavior disorder is also seen in people with PD. This sleep disorder can cause a person to act out their dreams, yell, scream, kick, or punch while sleeping, potentially injuring themselves by falling out of bed or unconsciously hitting their bed partner. REM sleep behavior disorder may be present many years before the motor symptoms of PD appear.
Daytime sleepiness — Excessive daytime sleepiness affects up to 75 percent of people with PD. Daytime sleepiness may be worsened by the medications used to treat PD. Some people just feel sleepy while others may experience sudden unintentional sleep "attacks" (causing the person to fall asleep unexpectedly during the daytime).
While sleep attacks are not common, both sleepiness and sleep attacks can be especially dangerous for people with PD who drive. People with PD should report these symptoms to their healthcare provider because medications may need to be altered. Most people with PD can continue to drive as long as their motor symptoms remain mild, but driving must usually be discontinued as motor and other symptoms worsen. (See "Patient education: Parkinson disease treatment options — education, support, and therapy (Beyond the Basics)".)
Fatigue — Fatigue is a constant feeling of significantly diminished energy. Over half of people with PD consider fatigue to be among their most disabling symptoms. It is often described as tiredness or exhaustion. Though there is overlap between fatigue, sleep disorders, and depression, people with PD can often separate fatigue from sleepiness.
Autonomic dysfunction — The autonomic nervous system works to control the unconscious or automatic functions of heart rate, digestion, breathing rate, perspiration, urination, and sexual arousal. Autonomic symptoms in PD can include low blood pressure after standing up (leading to lightheadedness or dizziness and falls), constipation, difficulty swallowing, abnormal sweating, urinary leakage, and sexual dysfunction (abnormally decreased or increased interest in sex).
Loss of sense of smell — Olfaction (the sense of smell) is commonly lost by people with PD. This usually happens early in the course of the illness, even before any of the more familiar symptoms appear and often without the patient noticing it. Difficulty detecting and identifying odors and discriminating one odor from another has been reported.
Pain — Painful sensations are reported in more than 40 percent of patients with PD. The pain can be piercing or stabbing, burning, or tingling, and may be felt in several places or only in specific areas of the body, including the face, abdomen, genitals, and joints. In general, painful sensations are experienced in the same body parts as the motor symptoms, and may be more prominent as medications wear off. (See 'Bradykinesia' above.)
PARKINSON DISEASE DIAGNOSIS — The signs and symptoms of PD can occur in people with other neurologic conditions. It is important to distinguish PD from these other conditions because treatment differs. However, it can be difficult to diagnose PD with certainty during the early stages of the disease.
Medical history and physical examination — There are no blood tests or imaging tests that can help to confirm the diagnosis of PD. As a result, the diagnosis is based upon a person's signs and symptoms, which are reviewed during a medical history and careful general physical and neurologic examination.
In general, two of the three primary symptoms (tremor, slow movement [bradykinesia], and rigidity) must be present to make the diagnosis, with one of the symptoms being slow movement (bradykinesia).
Other features that support the diagnosis include the following:
●Symptoms began on one side of the body
●The tremor occurs when the person's limb (arm) is resting
●The symptoms can be controlled with PD medications
During the medical history, the healthcare provider will ask the person when their symptoms began and if one or both sides of the body have been affected. The person (or family member or other close contact) should mention if there have been recent changes in mood, sleeping habits, bowel and bladder function, or ability to remember or think clearly. The healthcare provider will also ask about other medical conditions, current medications, recent injuries or falls, and difficulty walking or getting up.
The provider will perform a physical and neurologic examination to observe the patient's reflexes, muscles, balance while walking and standing, and ability to perform certain tasks with the hands.
Response to medication — The motor symptoms of PD generally improve significantly with medications. If the diagnosis of PD is uncertain and symptoms are bothersome, a medication challenge test may be recommended. This involves giving a medication commonly used to treat the symptoms of PD, such as levodopa, for at least two months. If the person's symptoms improve, the diagnosis of PD is likely.
By contrast, people with PD-like symptoms caused by other diseases, (such as progressive supranuclear palsy, multiple system atrophy, corticobasal degeneration, or dementia with Lewy bodies) typically do not improve with medication. A medication challenge is not usually recommended for people with mild symptoms that do not interfere with daily activities.
Imaging tests — Imaging tests, such as magnetic resonance imaging (MRI), are not usually helpful in confirming if a person has PD, although they may be used to rule out other possible diagnoses.
Dopamine transporter single-photon emission computed tomography (SPECT) imaging, also known as DaTscan, is a brain imaging test that can help to separate parkinsonism from a condition called essential tremor. The DaTscan is done by injecting a special type of dye that binds to the dopamine neurons in the brain. It can provide a sense of how many dopamine neurons are left in the brain. While it has been touted as a way to diagnose PD, the DaTscan cannot distinguish PD from other diseases that have symptoms similar to PD, such as progressive supranuclear palsy, multiple system atrophy, corticobasal degeneration, or dementia with Lewy bodies. For this reason, a good medical history and examination by an experienced clinician remain the best way to diagnose PD.
PARKINSON DISEASE PROGNOSIS — It is difficult to predict the outcome in a person with PD since this varies greatly from one person to another. Most people do well with treatment for many years, although there are no certainties. Naturally, many people with PD are concerned about becoming disabled and ultimately dying from PD. Although PD itself is not fatal, it increases the risk of dying from PD-related complications, such as falls, choking, or pneumonia.
Again, it is important to remember that progression is slow and that available medications may manage symptoms for a significant period of time.
PARKINSON DISEASE TREATMENT — There is no cure for PD, although medical and surgical treatments are effective for most people with the disease. A full discussion of treatment options is available separately. (See "Patient education: Parkinson disease treatment options — medications (Beyond the Basics)" and "Patient education: Parkinson disease treatment options — education, support, and therapy (Beyond the Basics)".)
WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem.
This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.
Patient level information — UpToDate offers two types of patient education materials.
The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.
Patient education: Parkinson disease (The Basics)
Patient education: Tremor (The Basics)
Patient education: Medicines for Parkinson disease (The Basics)
Patient education: Dementia with Lewy bodies (The Basics)
Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.
Patient education: Parkinson disease treatment options — medications (Beyond the Basics)
Patient education: Parkinson disease treatment options — education, support, and therapy (Beyond the Basics)
Patient education: Depression treatment options for adults (Beyond the Basics)
Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.
Bradykinetic movement disorders in children
Clinical manifestations of Parkinson disease
Diagnosis and differential diagnosis of Parkinson disease
Epidemiology, pathogenesis, and genetics of Parkinson disease
Management of nonmotor symptoms in Parkinson disease
Medical management of motor fluctuations and dyskinesia in Parkinson disease
Nonpharmacologic management of Parkinson disease
Overview of tremor
Cognitive impairment and dementia in Parkinson disease
Initial pharmacologic treatment of Parkinson disease
Device-assisted and lesioning procedures for Parkinson disease
The following organizations also provide reliable health information.
●National Library of Medicine
(https://medlineplus.gov/healthtopics.html)
●American Parkinson Disease Association
●The National Institute of Neurological Disorders and Stroke
(https://www.ninds.nih.gov/Disorders/All-Disorders/Parkinsons-Disease-Information-Page)
●Parkinson's Foundation
