That's the prospect for thousands diagnosed every year. Susan Seager examines the condition and asks what the future holds, while Betty Vandenberg gives a personal view. The cause is unknown and there is currently no cure (Parkinson's Disease Society), Treatment hope for Parkinson's patients (The Guardian).

The first statement seems to say it all. Yet barely a week goes by without a headline like the one above. So what is the prospect for the four million worldwide (120,000 of them in the UK) estimated to have this progressive neurological disorder?

For reasons currently unknown, cells in the part of the brain controlling movement (the substantia nigra) start to die. As these cells produce dopamine, the chemical that enables us to perform tasks smoothly, once 80 per cent have gone the symptoms of Parkinson's appear.

The main symptoms are shaking, muscle stiffness and slow movement - although not all will be experienced. Problems with balance, posture, speech, swallowing, writing and facial expression can also develop and, not surprisingly, depression can descend.

The symptoms can develop gradually. At first sufferers might feel extremely tired, have difficulty concentrating and speak more softly. As there is no specific test for Parkinson's, diagnosis relies on assessment of symptoms.

Possible causes

As the Parkinson's Disease Society (PDS) reports, and despite years of research, the cause has still not been tracked down. The likeliest explanation is that a number of factors are at work. For instance, one line of enquiry is based on gender differences since men are more likely to be affected and experience more rapid development of the disease than women. Could female oestrogen hormones be providing a protective effect?

Another area of concern was highlighted by the Government's scientific advisers who recently called for more research into pesticide exposure since farmers have a higher than average risk of acquiring the disorder. An EU study is currently investigating the possible link but UK scientists are calling for specifically British research since farming practices and climate vary from one country to another.

What is clear, given that only one in 20 sufferers is under 40, is that ageing is a factor, particularly in those with a genetic predisposition to the disease - something more evident in women than men.

One branch of research has been looking at the possible role of free radicals in the death of cells in the substantia nigra, while another has been focusing on damage triggered by high levels of the amino acid homocysteine in the blood - also a possible culprit in the development of Alzheimer's. Up to 15 per cent of the general population is not able, for genetic reasons, to break down homocysteine effectively and, following the menopause, some women are less able to do so.

Does diet play a part?

It's been noticed that Parkinson's sufferers often have low levels of folic acid. What isn't known is whether this is part of the illness or related to diet. However, research has shown that folic acid, found in fortified cereals, green leafy vegetables and citrus fruit, may encourage repair of damaged brain cells. Folic acid, along with vitamins B6 and B12, aids the breakdown of homocysteine (see "Possible causes" above). What is more, the free radical damage thought to be implicated in the death of cells can be minimised by antioxidants found in many fruit and vegetables.

A small trial also indicated that taking high doses of co-enzyme Q10, already known to protect heart muscle cells, helped slow the progression of Parkinson's, but further, more extensive study is needed before any definite conclusions can be drawn.

Treatment

Without a known cause, treatment focuses on alleviating symptoms. If these are mild, all that is necessary might be regular exercise and physiotherapy.

Where symptoms are more severe, drugs are prescribed to restore dopamine levels. The amino acid levodopa and selegiline are the most commonly used. Although initially very effective, in the long-term these drugs can trigger severe side-effects such as confusion and hallucinations.

Surgical options are available such as lesioning, gamma knife surgery, deep-brain stimulation and tissue implants. The arrival of magnetic resonance imaging (MRI) technology has increased the accuracy of such interventions. With deep-brain stimulation, patients have electrodes implanted in their brain connected to a device, which they can then control according to the severity of the symptoms.

Physiotherapy, speech and language therapy and occupational therapy also help to support patients in the management of their condition.