Most doctors say that Parkinson’s disease itself is not fatal. You die with Parkinson’s disease, not from it. However, as symptoms worsen they can cause incidents that result in death. For example, in advanced cases, difficulty swallowing can cause Parkinson’s patients to aspirate food into the lungs, leading to pneumonia or other pulmonary conditions. Loss of balance can cause falls that result in serious injuries or death. The seriousness of these incidents depends greatly on the patient’s age, overall health and disease stage.

While a small percentage of Parkinson’s disease cases are caused by genetic changes, the large majority are not. Nonetheless, scientific data over the past several years supports the emerging belief that genetics plays a more significant role in Parkinson’s disease than was previously thought. Understanding in this field is evolving rapidly. Today, most scientists believe that the majority of Parkinson’s disease cases are likely caused by one or more genetic factors combined with exposure to one or more environmental neurotoxins, such as pesticides or other chemicals.

Parkinson’s disease symptoms occurs when nerve cells, or neurons, in an area of the brain known as the substantia nigra die or become impaired. Normally, these neurons produce an important brain chemical known as dopamine. Dopamine is a chemical messenger responsible for transmitting signals between the substantia nigra and the next “relay station” of the brain, the corpus striatum, to produce smooth, purposeful movement. Loss of dopamine results in abnormal nerve firing patterns within the brain that cause impaired movement.

Parkinson’s disease is sometimes referred to as a “boutique” disease: It is unique to each person. You cannot predict which symptoms you will get, and when you will get them. There are broad paths of similarity as the disease progresses, but there is no guarantee that what you see is what you’ll get. Some people wind up in wheelchairs; others still run marathons. Some can’t clasp a necklace, while others make necklaces by hand. Some of the more pronounced symptoms of people who are in mid- or late-stage Parkinson’s disease, include dyskinesia (the involuntary flailing or jerking body movements that can result from long-term use of levodopa, the most common Parkinson’s disease medication), freezing (the sudden inability to move) or festination (the short, almost running steps that seem to accelerate on their own). Remember that Parkinson’s disease is highly individualistic and your disease may never encompass any of these symptoms.

Parkinson’s disease impacts people in different ways. Not everyone will experience all the symptoms of Parkinson’s, and if they do, they won’t necessarily experience them in quite the same order or at the same intensity. There are typical patterns of progression in Parkinson’s disease that are defined in the following stages:

Stage One
During this initial stage, the person has mild symptoms that generally do not interfere with daily activities. Tremor and other movement symptoms occur on one side of the body only. Changes in posture, walking and facial expressions occur.

Stage Two
Symptoms start getting worse. Tremor, rigidity and other movement symptoms affect both sides of the body. Walking problems and poor posture may be apparent. The person is still able to live alone, but daily tasks are more difficult and lengthy.

Stage Three
Considered mid-stage, loss of balance and slowness of movements are hallmarks. Falls are more common. The person is still fully independent, but symptoms significantly impair activities such as dressing and eating.

Stage Four
At this point, symptoms are severe and limiting. It’s possible to stand without assistance, but movement may require a walker. The person needs help with activities of daily living and is unable to live alone.

Stage Five
This is the most advanced and debilitating stage. Stiffness in the legs may make it impossible to stand or walk. The person requires a wheelchair or is bedridden. Around-the-clock nursing care is required for all activities. The person may experience hallucinations and delusions.

About 1 million individuals have been diagnosed with Parkinson’s disease in the United States and as many as 10 million people worldwide, with an estimated 60,000 new cases diagnosed in the United States annually. However, getting an accurate count of the number of cases may be impossible because many people in the early stages of the disease assume their symptoms are the result of normal aging and do not seek help from a physician. Additionally, diagnosis is sometimes difficult and uncertain because other conditions may produce symptoms of Parkinson’s disease and there is no definitive test for the disease. People with Parkinson’s disease may sometimes be told by their doctors that they have other disorders, and people with Parkinson’s disease-like diseases may be incorrectly diagnosed as having Parkinson’s disease.

Parkinson’s disease strikes about 50 percent more men than women, but the reasons for this discrepancy are unclear. While it occurs in people throughout the world, a number of studies have found a higher incidence in developed countries, possibly because of increased exposure to pesticides or other toxins in those countries. Other studies have found an increased risk in people who live in rural areas and in those who work in certain professions, although the studies to date are not conclusive and the reasons for the apparent risks are not clear.

People are generally most familiar with the motor symptoms of Parkinson’s disease, since they are the most externally noticeable. These symptoms, which are also called the “cardinal” symptoms of Parkinson’s disease, are: resting tremor, slowness of movement (bradykinesia), postural instability (balance problems) and rigidity. Some other physical symptoms such as gait problems and reduced facial expression are also of note. These are due to the same discoordination of movement that causes the better-known tremor and slowness.

There is also increasing recognition of the importance of other Parkinson’s disease symptoms that are sometimes called “non-motor” or “dopamine-non-responsive.” While neither of these terms is ideal, these symptoms are common and can have a major impact on Parkinson’s patients. For example, cognitive impairment, ranging from mild memory difficulties to dementia, and mood disorders, such as depression and anxiety, occur frequently. Also common are sleep difficulties, loss of sense of smell, constipation, speech and swallowing problems, unexplained pains, drooling and low blood pressure when standing.

Parkinson’s disease symptoms manifest differently in different patients. Many patients experience some symptoms and not others, and even the pace at which the disease worsens varies from person to person.

Parkinson’s disease is a neurodegenerative disorder that affects predominantly dopamine-producing (“dopaminergic”) neurons in a specific area of the brain called substantia nigra. The substantia nigra cells produce dopamine, a chemical messenger responsible for transmitting signals within the brain that allow for coordination of movement. Loss of dopamine causes neurons to fire without normal control, leaving patients less able to direct or control their movement. Parkinson’s disease is one of several diseases categorized by clinicians as movement disorders. Average age of onset for Parkinson’s disease is 60 although some individuals are diagnosed at 40 or younger.

Getting a second opinion is largely a matter of personal choice. But keep in mind that Parkinson’s disease is often difficult to diagnose accurately, particularly when symptoms are mild. There is no simple diagnostic test, and approximately 25 percent of Parkinson’s disease diagnoses are incorrect. Parkinson’s disease starts out with such subtle symptoms that many physicians, who are untrained in it, fail to provide an accurate diagnosis. In fact, even the best neurologists can get it wrong. We would recommend that unless your doctor is particularly experienced in this area, you consult with a movement disorders specialist. A good neurologist will understand your desire for confirmation. If it is affordable (insurance doesn’t always cover second opinions), and brings peace of mind, a second opinion can help you and your loved ones come to terms with your disease.

The cardinal symptoms of Parkinson’s disease are resting tremor, slowness of movement (bradykinesia) and rigidity. Many people also experience balance problems (postural instability). These symptoms, which often appear gradually and with increasing severity over time, are usually what first bring patients to a neurologist for help. Typically, symptoms begin on one side of the body and migrate over time to the other side.

There is no objective test (such as a blood test, brain scan or EEG) to make a definitive diagnosis of Parkinson’s disease. Instead, a doctor takes a careful medical history and performs a thorough neurological examination, looking in particular for two or more of the cardinal signs to be present. Frequently, the doctor will also look for responsiveness to Parkinson’s disease medications as further evidence that Parkinson’s is the correct diagnosis. (However, starting on medication right away can limit your ability to participate in clinical trials that urgently need newly-diagnosed Parkinson’s patients.)

In 2011, the Food and Drug Administration (FDA) approved a specialized imaging technique called DaTscan that allows doctors to capture detailed pictures of the dopamine system in your brain. It is the first FDA-approved diagnostic imaging technique for the assessment of movement disorders such as Parkinson’s disease. DaTscan alone can’t diagnose Parkinson’s disease by itself, but it can help confirm a physician’s clinical diagnosis — something that has never been possible before. Unfortunately, because there is no definitive test for Parkinson’s disease, and because Parkinson’s disease symptoms are similar to those of other neurological conditions, the misdiagnosis rate remains significant. It is worthwhile to consider a second opinion, and to reach out to a neurologist with specific expertise in movement disorders.