What is Parkinson's disease?

Parkinson's disease is a degenerative condition of the brain that causes problems with controlling movements, as well as a range of other symptoms. Parkinson's disease is one of the most common conditions to affect the central nervous system in older people. It can happen to anyone, however it:

  • Mostly occurs in people over 50 years of age;
  • Is more common in men than in women, and;
  • Can occur in younger adults, but is rare in children.

Central nervous system

The part of the body's nervous system that includes the brain and the spinal cord.

Causes

Parkinson's disease is caused by slowly accumulating damage to a part of the brain called the substantia nigra. This leads to a reduced production of dopamine. Dopamine is a chemical messenger in the brain that is necessary for a person to perform smooth controlled movements.

The reason why this damage occurs to the brain is not currently understood. In a small number of cases the occurrence of Parkinson's disease may run in families. In people who develop Parkinson's disease at a young age, the condition is more likely to be genetic.

Genetic

Related to genes, the body's units of inheritance or origin.

Types

It is important to note that not all individuals with symptoms of Parkinson's disease have the disorder. Other conditions can also give rise to the similar symptoms. One related condition called Parkinson-plus syndrome can have symptoms similar to Parkinson's disease, but with other symptoms such as prominent memory loss or psychosis. Parkinson-plus syndrome may arise due to side-effects of certain medications, other illnesses (such as AIDS or meningitis), or a different condition of the nervous system (such as stroke).

It is important to differentiate these conditions from the actual Parkinson's disease to improve treatment outcomes. 

AIDS

Acquired immune deficiency syndrome (AIDS) is a group of conditions, including infections and tumours, that develop due to a defective immune system caused by the human immunodeficiency virus (HIV).

Signs and symptoms

There is a wide range of symptoms caused by Parkinson's disease and they develop differently for each person. In many cases symptoms develop slowly, affecting one side of the body first.

Movement

The main symptoms of Parkinson's disease are:

  • Tremor (uncontrollable shaking). Tremors usually starts in one hand or arm and then spread to other parts;
  • Stiffness (rigidity) in the muscles. This can lead to symptoms such as a stooped posture, muscle cramps and difficulty making facial expressions;
  • Slowness of movement (bradykinesia). People with Parkinson's disease often have a slow, shuffling walk, and;
  • Balance problems. Automatic reflexes that assist balance tend to fail, making people less steady on their feet and more prone to falling.

Symptoms such as tremors can tend to be worse when you are tired, anxious or stressed.

As symptoms progress, people with Parkinson's disease can find it more difficult to do many of the daily activities, such as walking, getting out of a chair, turning over in bed and activities that require fine hand movements such as writing and eating.

An elderly man with Parkinson's disease symptoms including tremor, rigid muscles and slow walk.Symptoms of Parkinson's disease include rigid muscles, tremors and slowness of movement. 

Cognitive problems

Some people with Parkinson's disease can experience difficulties with thinking (such as making decisions) and memory. The severity of these problems can vary a lot between different people.

Symptoms due to autonomic dysfunction

Parkinson's disease can also affect the autonomic nervous system, affecting many of the automatic processes in the body. Symptoms can include:

  • Low blood pressure after standing up;
  • Constipation;
  • Problems swallowing;
  • Urinary incontinence, and;
  • Abnormal sweating and problems controlling body temperature.

Mental health problems

People with Parkinson's disease are at an increased risk of mental health issues such as depression, anxiety and difficulties with motivation. Not only can these issues affect quality of life, they can also make movement problems worse.

Other symptoms

Other symptoms that can occur with Parkinson's disease include:

  • Problems with sleeping, excessive tiredness during the day;
  • Loss of the ability to smell;
  • Vision problems, and;
  • Pain.

Anxiety

A feeling of tension, nervousness and dread about future events. It can trigger physical symptoms such as a rapid pulse or breathing difficulties.

Autonomic nervous system

The arm of the nervous system that operates with no conscious influence. Controls the heartbeat, digestion, breathing and glands.

Methods for diagnosis

There is no single test for Parkinson's disease. Your doctor may perform a physical examination and ask you about your symptoms. You may be requested to perform a range of tests or exercises to allow your doctor to better gauge the extent of your symptoms.

Your doctor will need to rule out other potential causes, which can be difficult, particularly if the symptoms are very mild.  A single photon emission computed tomography (SPECT) scan may be recommended in some cases to support the diagnosis of Parkinson's disease and try to rule out other causes.

Types of treatment

There is no cure for Parkinson's disease, so treatment is aimed at relieving the symptoms, rather than slowing down damage to the brain.

Deciding on when to start treatment is a decision that will depend in part on how much the symptoms are bothering you. Over time you will need to regularly review your treatment with your doctor.

Medications

When taking medications for Parkinson's disease, it is very important to follow the directions of your doctor. Not taking medications on time can lead to more severe symptoms and increased movement difficulties.

Levodopa

Levodopa is a medication that is converted to dopamine in the brain and the other areas of the body. When administered early on, it tends to have a large effect on symptoms, but over time, as more cells in the brain are damaged by Parkinson's disease, it tends to be less effective.

Levodopa can cause significant side effects such as nausea and vomiting when it is broken down in the body, so medications containing it also contain other ingredients such as carbidopa and benserazide to help prevent this from happening.

People taking levodopa for long periods of time (5-10 years) can experience delayed side effects including:

  • Unwanted movements of the arms, legs and torso (dyskinesia);
  • Muscle cramps and contractions (dystonia), particularly in the feet, and;
  • Changes in movement that tend to occur towards the end of a dosage period, in what is sometimes called the 'wearing-off' effect.

Some medications can help with these delayed side effects.

Amantadine is a medication that may be prescribed for people who have developed side-effects, such as dyskinesia due to taking levodopa.

Catechol-O-methyl transferase (COMT) inhibitors, such as entacapone and tolcapone, can help to slow the breakdown of levodopa and prolong its effect. They can be particularly helpful for people who experience a significant wearing-off effect with levodopa.

Dopamine agonists

Dopamine agonists, such as bromocriptine, pergolide and carbergoline, are compounds that mimic the effect of dopamine in the brain. They may be prescribed on their own, or in combination with levodopa. They tend to have a similar but lesser effect and are often used early in treatment. They are less likely to cause unwanted movements.

Monoamine oxidase-B (MAO-B) inhibitors

These medications block an enzyme in the brain, known as monoamine oxidase-B, that breaks down dopamine, thereby allowing it to work for longer. Examples include selegiline and rasagiline and they may be used on their own, or in conjunction with levodopa.

Anticholinergics

Acetylcholine is a chemical messenger that is present in the brain in high levels in people with Parkinson's disease. Anticholinergics work by reducing levels of acetylcholine in the brain and helping to balance levels of dopamine. Examples include benzhexol and benztropine. They may be prescribed alone, or in combination with levodopa.

Surgery

For people whose symptoms cannot be satisfactorily controlled with medications, a surgical technique called deep brain stimulation may be available. It is not suitable for everyone with Parkinson's disease, but for some people it can markedly improve some of the symptoms. Most people who have deep brain stimulation will still need to take medication, but often at a reduced dosage.

Before surgery, the exact position in the brain that requires stimulation is identified. This can be done using a magnetic resonance imaging (MRI) or computerised tomography (CT) scan and, in some cases, a technique called microelectrode recording (MER) may be performed at the time of the actual surgery. 

During the surgery:

  • A small hole is made in the skull so that a thin wire (called the lead) with an electrode on its tip can be implanted in the target area of the brain;
  • A long wire (called an extension) is placed under the skin so that it runs down the head, neck and shoulder, and;
  • An implantable pulse generator, a unit much like a small battery pack, is implanted near the collarbone or lower in the chest or abdomen and connected to the extension.

Once the system is working, the generator sends electrical pulses along the extension and lead, helping to block abnormal electrical signals in the brain caused by Parkinson's disease.

: A diagram of a man showing the positions of the lead in the brain and implantable pulse generator in the chest in deep brain stimulation.Deep brain stimulation can improve symptoms of Parkinson's disease. 

Other therapies

The symptoms of Parkinson's disease can have a big effect on many aspects of your life. Managing symptoms and finding ways to minimise its impact on your health, fitness, work and social life are an important part of living with the condition.

Some healthcare professionals that may be able to help include:

Physiotherapists

Physiotherapists can help with improving symptoms such as muscle stiffness and pain. Through manipulation and exercise, they can help you to improve your flexibility, fitness levels and walking.

Occupational therapists

Occupational therapists can help you identify situations and daily activities that are causing difficulty and find practical ways to deal with them. Setting up your home and work area so that it is safe and functional will enable you to maintain your independence in a safe environment.

Speech therapists

For people with speech or swallowing difficulties, a speech therapist can help.

Dietitian

Parkinson's disease can cause a range of problems with digestion (such as constipation) and low blood pressure. A dietitian can give guidance on following a healthy diet to help to reduce these symptoms, and;

Mental health professionals and support groups

Adjusting to a diagnosis of Parkinson's disease and living with the symptoms can be challenging. People with Parkinson's disease are at increased risk of mental health problems, such as depression and anxiety. Talking to a mental health professional or joining a support group (see link) where you can connect with other people living with the condition can help.

Anxiety

A feeling of tension, nervousness and dread about future events. It can trigger physical symptoms such as a rapid pulse or breathing difficulties.

Computerised tomography

A scan that uses X-rays to create a 3D image of the body. This can detect abnormalities more effectively than a simple X-ray can.

Microelectrode recording

A technique, carried out under a local anaesthetic, in which a very small electrode is inserted into the brain tissue to record activity of the nerve cells.

Magnetic resonance imaging

A type of imaging that uses a magnetic field and low-energy radio waves, instead of X-rays, to obtain images of organs.

Potential complications

Parkinson's disease and its treatment can cause a range of complications and side-effects, respectively. Working with your health care practitioners to manage these issues as effectively as possible can help to minimise their impact on your life.

Medications

Medications for Parkinson's disease are powerful and can cause severe side-effects in some people. These differ depending on the medication and individual reactions, but can include nausea, vomiting and diarrhoea. Some side effects can be particularly concerning for people on Parkinson's disease medications, including confusion, psychotic symptoms and problems with impulse control. Psychosis means a state of thinking where a person loses touch with reality. One of the symptoms of psychosis can be visual hallucinations - seeing things that are not really there. Another can be having delusions and fears (for example, being excessively worried about money being stolen). Disorders of impulse control affect someone's ability to control aspects of their lives such as gambling, spending money and appropriate internet use.

If you are concerned about side-effects, letting your doctor know is important to the treatment of Parkinson's disease. It is important not to stop taking medication without talking to your doctor because stopping medication suddenly can cause Parkinson's disease symptoms to become worse. Rather, if your doctor knows about your side-effects, they may be able to alter the dose or change your medications, to reduce the side-effects.

Interactions with other medications

It is important to take care with medications for other conditions when you have Parkinson's disease. Many medications can:

  • Make Parkinson's disease symptoms worse, and;
  • Interact with your Parkinson's disease medications and cause serious side-effects.

Some medications that can particularly cause problems are:

  • Medications for nausea, such as metoclopramide or prochlorperazine;
  • Some antidepressants, and;
  • Some medications for blood pressure.

You can help to avoid these problems by making sure that any healthcare professional that gives you medications knows what Parkinson's disease medications you are on. Also, you can ask your doctor or pharmacist about potential side effects or interactions for any new medications that you are prescribed.

Increased risk of disability

Because of the symptoms that affect movement and swallowing, people with Parkinson's disease can be at greater risk of disability and death due to issues such as:

  • Injury due to falling;
  • Choking because of swallowing problems, and;
  • Developing pneumonia due to inhalation of saliva (aspiration pneumonia).

Working with healthcare practitioners, such as physiotherapists and occupational therapists, to stay as fit and mobile as possible, and improve safety around your home and work area, can help to reduce these kinds of risks.

Aspiration pneumonia

An inflammation of the lungs and airways as a result of inhaling foreign material such as food, saliva or vomit.

Prognosis

There is currently no cure for Parkinson's disease, so the available treatments target symptoms rather than slowing the progress of the condition. Research into slowing the progression of the disease is ongoing.

The severity of symptoms with Parkinson's disease and the progression of the condition vary considerably from person to person. Many people, on proper medication, can manage their symptoms for years.

Parkinson's disease does not cause death. However, some of the complications, such as pneumonia and an increased risk of falling due to movement and balance problems, can lead to injury and death.

Prevention

Parkinson's disease cannot be prevented at this point in time. There is, however, ongoing research into the various aspects of this disease.