What it's all about (Parkinson's Disease)

What is Parkinson's Disease?

Dr James Parkinson first identified the condition, which he called "shaky palsy", in 1817.

It is a chronic (long-term), non-fatal, degenerative neurological disorder that impairs movement and speech. Though it is most common in the over-50s, one in 20 of those diagnosed is under 40.

Juvenile Parkinson's - affecting those under 18 - is extremely rare.

Men are slightly more likely to develop Parkinson's than women, but no one knows why.


What causes it?

Characterised by muscle rigidity, tremors - commonly referred to as "the shakes" - fatigue and, in extreme cases, total loss of mobility, the primary symptoms are due to a loss of nerve cells in the substantia nigra, part of the brain producing dopamine to aid movement co-ordination.

With depletion of dopamine-producing cells, parts of the brain can't function normally.

Parkinson's symptoms appear when about 80 per cent of dopamine has been lost.

Dopamine levels continue to fall for years. Researchers believe it is caused by genetics - nine genes linked to Parkinson's have been identified - plus environmental factors.


What are the symptoms?

"They vary greatly - a third of patients don't experience tremors," says Professor Ray Chaudhuri, of the Movement Disorders Unit at King's College Hospital, London.

"Other early warnings can include difficulty in writing, performing simple manual tasks such as tying shoelaces and holding cutlery, or the dragging of a limb.

"There is a feeling of stiffness, accompanied by numbness. One almost universal symptom is a loss of sense of smell - sufferers can't smell oregano."

Slowness or difficulty in initiating movement - bradykinesia - is common, as is muscle rigidity.

Disturbed sleep, bowel problems, incontinence, memory problems and depression are common "non-motor" symptoms, all linked to depleted levels of dopamine.

"The progression of the disease is usually slow for the first 15 years, after which decline can be rapid.

"As the disease advances the bottom half of the body can freeze. It's distressing, but not usually painful," says Professor Chaudhuri.

The symptoms of Parkinson's develop gradually.

There are no specific tests to prove if someone has the condition. Patients are diagnosed on medical history and a clinical examination.

The symptoms can have other causes and tests and scans may be needed to rule these out.


Is there a cure?

"There is no cure," says Professor Chaudhuri. "But it is treatable and manageable.

In the early stages, many rely on a healthy lifestyle - diet, exercise and relaxation. Later, drugs can also be used."

A new treatment, licensed for UK use in 2006, is the Neupro patch, made by Schwarz Pharma.

The patch contains a dopamine agonist - an agent that acts directly on the dopamine receptors in the brain - called rotigotine, and delivers a continuous dose of the drug over 24 hours, so patients have to change the patch only once a day.

Medications increase the level of dopamine reaching the brain, stimulate the areas where dopamine works, and block the action of other chemicals that reduce dopamine's effect.

Surgery is also available, depending on symptoms.

Deep-brain stimulation involves implanting a wire, with four electrodes at its tip, into the thalamus, the globus pallidus or the subthalamic nucleus - all parts of the brain connected to movement and co-ordination.

The wire is connected to a small implantable pulse generator (IPG) inserted under the skin, often in the chest, like a pacemaker.

The IPG sends electrical signals to the brain to stop or reduce Parkinson's symptoms.

Lesioning is another option. An electrode is inserted into the brain, causing selective damage to certain cells in the thalamus (thalamotomy) or globus pallidus (pallidotomy).

Unlike deep-brain stimulation, this is irreversible and less common.

There have been promising developments in coaxing human stem cells - premature cells that can become any of a number of mature cells in the body under the right conditions - to form dopamine-producing brain cells in rats, but treatment in humans is still a long way off.

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