Parkinson's disease is caused by a degeneration of the cells which produce dopamine in the substantia nigra area of the brain. It is not known why the cells are damaged or destroyed although there are many theories. It is possible that genetics and the environment work together to cause Parkinson's. Much more research is needed to completely understand how, why and when this disorder occurs. The symptoms of Parkinson's appear when over half of the dopamine-producing cells are lost.

Dopamine is a brain neurotransmitter which sends signals from one nerve cell to another. It affects the parts of the brain which control smooth, voluntary movements such as walking, writing, throwing a ball or buttoning a shirt.

Dopamine is also essential for involuntary movements including control of: blood pressure and bowel function.

Loss of dopamine can also affect mood and thinking.

There are no specific brain scans or laboratory tests to confirm the diagnosis of Parkinson's. Neurologists diagnose it with a careful evaluation of a person's medical history and a physical examination. Tests may be done to rule out other conditions which may resemble Parkinson's.

At the present time there is no known cure, however many people live full, productive lives. With the treatment that is now available, life expectancy for someone with Parkinson's is fairly normal. Each year, more and improved treatments are being introduced.

There are approximately 100,000 people with Parkinson's in Canada, approximately 15,000 (Ministry of Health, 2019/20) in British Columbia. Up to 20% of individuals with Parkinson's develop symptoms before the age of 60. This is known as Young Onset Parkinson's. Parkinson's is usually diagnosed between the ages of 55 and 65, with 60 being the average age of diagnosis. Parkinson's affects 1% of adults over the age of 65 and is slightly more common in men.

A genetic cause of Parkinson's appears in only a very small number of cases, approximately 5% – 10%. Where it may appear to run in families, researchers are looking at environmental factors shared by the family or community in addition to examining potential genetic links. The vast majority of cases of Parkinson's disease are from unknown causes.

Most common motor symptoms are:

• Resting tremor – repetitive shaking movements occurring in the arms and/or legs at rest. (Tremors are the first symptom to appear in about 70% of people with Parkinson's.)
• Rigidity – increased stiffness in muscles and joints.
• Bradykinesia – slowness of movement, including all actions such as walking and writing.
• Lack of coordination – postural impairment or loss of balance.

Other symptoms:

• Hypomimia – reduced facial expression, making a person appear uninterested or sad when they are not.
• Hypophonia – speaking in a very soft voice. This may involve deterioration in the rhythm and quality of the voice.
• Micrographia – small, cramped handwriting.
• Cognitive and mood changes, including:
  • Depression
  • Anxiety
  • Forgetfulness and confusion
  • loss of impulse control
  • Dementia, hallucinations
  • Delusions

• Urinary problems
• Pain
• Constipation

Early symptoms generally occur gradually, and progress more rapidly in some people than others. The tremor may begin to interfere with daily activities, and other symptoms may appear. Parkinson is progressive, meaning the symptoms may worsen over time, and the rate of this progression is different for each person. There is no way of knowing how slowly or quickly Parkinson's may progress. Parkinson's is, however, described as the most slowly progressing neurological disorder.

Mental illness is a term used to describe a disruption in the balance between mind, body and spirit and a change in one's mental or emotional well-being. Psychological symptoms of Parkinson's are considered to be as important as the physical symptoms.

Some people feel there is a stigma associated with mental health issues and some may still feel that psychological symptoms are an example of personal weakness. Do not allow these preconceptions to stop you from talking to your healthcare professionals and getting the help you need!

Note to caregivers:

Some caregivers report that the psychological changes that can accompany Parkinson's are more difficult to deal with than the physical changes. It is therefore even more important for caregivers to look after themselves.

Adapted from Mind, Mood and Memory, published by the National Parkinson Foundation. 

There are many causes of tremors and other symptoms associated with Parkinson's disease and it may take time to make an accurate diagnosis. A neurologist who specializes in movement disorders is the best person to make or confirm a diagnosis. The following information describes other disorders that may be confused with Parkinson's.

Many of the conditions described in this section are extremely rare.

Essential Tremor (ET)
Sources: International Essential Tremor Foundation, The Mayo Clinic

Essential Tremor is a chronic neurological condition characterized by involuntary, rhythmic tremor of a body part. The most frequently affected areas of the body are the hands, arms and head, followed by the voice, tongue, legs, or trunk.

ET is considered a slowly progressive disorder although for some people it may be relatively non-progressive and the tremor may be mild throughout life. Essential tremor isn't caused by other conditions and it is a common movement disorder.

Medication is a common treatment and many people with ET benefit from drug therapy, however not everyone is a candidate for the medications used to treat ET.

Surgery may be suggested to treat ET but individuals are carefully selected as possible candidates for surgery and surgical intervention is usually reserved for patients with severe, disabling tremor.

Finally, lifestyle changes as well as physical and occupational therapy may help individuals better perform tasks that are affected by ET.

Medication-Induced Parkinsonism

Some common medications can cause Parkinson-like symptoms. Medications frequently associated with the development of Parkinsonism (the name given to a group of disorders with similar features including four primary symptoms: tremor, rigidity, slowness of movement and postural instability) include antipsychotics, metaclopramide, reserpine, tetrabenazine and some blood pressure medications such as cinnarizine and flunarizine. Fortunately, the symptoms usually abate within weeks to months after discontinuing the problem medication.

This is one reason why it is very important to inform the medical staff in a hospital or clinic that you have Parkinson's and what medications you are taking. A Medication Card, which may be obtained from Parkinson Society British Columbia, is a very useful tool for keeping track of your medications. The card contains a clear message regarding medications that must not be taken by a person with Parkinson's.

Vascular Parkinsonism

Multiple small strokes can cause Parkinson's-like symptoms. People with this disorder are more likely to have gait difficulty rather than tremors and are more likely to have symptoms that are worse in the lower limbs rather than the upper limbs. Some will also report the abrupt onset of symptoms or give a history of a step form of symptom development (symptoms get worse, then plateau for a period, then get worse again). Treatment is the same as for Parkinson's disease, but the results are often not as positive.

Parkinson's Plus Syndromes

Parkinson-plus syndromes are a group of neurological conditions that are similar to Parkinson's disease but have unique characteristics. These syndromes can be hard to diagnose because the symptoms mimic other conditions. Read more about these syndromes here.