What causes Parkinson's?

Parkinson's disease (PD) is a chronic, progressive condition that affects an area of the brain known as the substantia nigra. This deterioration results in decreased output of a chemical called dopamine, one of several chemicals called neurotransmitters that relay messages between brain cells.

The cause of Parkinson's disease is unknown but, as with so many other conditions, age is a major factor: the risk of the disease rises with age, although it can hit younger people, too.

Researchers know that genetics play a small role in Parkinson's disease. You have a greater risk of getting Parkinson's disease if you have a relative with it, and the more relatives you have with Parkinson's disease, the higher your risk. Exposure to toxins may also increase the risk of Parkinson's disease.

Symptoms of Parkinson's

The main symptoms of Parkinson's include:

  • tremor
  • muscle rigidity or stiffness
  • slowness of movement
  • balance problems

Other symptoms can include:

  • constipation and urinary difficulties
  • depression
  • gradual loss of "automatic movements" such as blinking and smiling
  • muscle weakness
  • sleep disturbances
  • speech deterioration
  • visual or auditory hallucinations

In the latter stages of the disease, a significant proportion of people develop dementia.

There is no specific test for Parkinson's, although it's generally not hard to make the diagnosis from the symptoms alone.

Treatment of Parkinson's disease

There is no cure for Parkinson's disease, but medications can help improve symptoms. Levodopa, combined with carbidopa or benserazide, is one of the main medications used to treat Parkinson's disease. Levodopa is converted into dopamine in the brain (dopamine itself cannot get into the brain because it can't cross the blood-brain barrier, but levodopa can). Carbidopa prevents the conversion of levodopa to dopamine until levodopa reaches the brain. Benserazide is another medication that works the same way as carbidopa and is given with levodopa.

Entacapone decreases the breakdown of levodopa in the body and increases the amount that gets into the brain. It is given with the combination of levodopa and carbidopa or benserazide to improve symptoms during the later stages of the disease. Levodopa helps with slowed movements and rigidity and can help tremor too. However, with prolonged treatment, it does not work as well or for as long and can cause fluctuations in movement control.

Another group of medications, called dopamine agonists (e.g., pramipexole, ropinirole, bromocriptine), works by stimulating dopamine receptors in the brain. Rasagiline and selegiline belong to a class of medications called monoamine oxidase B (MAO-B) inhibitors, which work by preventing the breakdown of dopamine in the brain. Amantadine and anticholinergic medications (e.g., benztropine) are also options in the early stages of Parkinson's disease, however anticholinergics are recommended mainly for younger people with Parkinson's (in older people they can cause confusion and memory problems). Amantadine may help to reduce bouts of stiffness and unpredictable movements (also known as dyskinesias) that are brought about by long-term use of levodopa.  

In later stages of Parkinson's disease when medications aren't helping, surgical procedures such as deep brain stimulation (DBS) or lesioning may be done. For deep brain stimulation, electrodes are implanted in the brain and are stimulated by an electrical device. Deep brain stimulation can help improve symptoms and reduce the need for medication, and is the usual surgical procedure for people with severe forms of the disease. For lesioning, specific areas of the brain are intentionally damaged to reduce symptoms. Although this is an option for some, it is not routinely recommended because the procedure comes with a high risk of irreversible side effects.

For anyone with Parkinson's disease, remaining active and getting regular exercise is important. If you're not sure what you can do safely, talk to your doctor or physiotherapist. You may also need assistance from other health care professionals such as speech therapists and occupational therapists.

Written and reviewed by the MediResource Clinical Team