The European Federation of Neurological Associations has published a booklet that is intended to help people who may have neurological symptoms and conditions, as well as anybody who is interested. Here's an extract from the booklet that discusses Parkinson’s disease. Robert Griffith, Medical Editor.

Parkinson's disease - What is it?

Parkinson's disease is a progressive but not fatal neurological condition. It occurs most commonly in older people. Damage occurs to cells in the part of the brain that controls movement. The rate of progression of the disease and the way the symptoms manifest themselves vary greatly from one individual to another.

Symptoms may include trembling (tremor), stiffness, slowness and poor balance. Parkinson's disease may lead eventually to hesitant speech, abnormal posture, slowness of movement and a stiff, shuffling walk. In some cases mental processes may be slowed and memory impaired. However, not all people with Parkinson's disease are affected by all these symptoms.

Medication is very effective in most cases in relieving symptoms; surgical techniques have proved useful in helping some people whose symptoms are not well managed by medication.

Other conditions may cause symptoms similar to those of Parkinson's disease - so-called parkinsonism. For example, people who have had multiple small strokes may develop stiffness and imbalance. In some cases these conditions are reversible; in others the symptoms respond to medications used in treating Parkinson's disease. Medications used to treat certain neurological conditions, such as schizophrenia, may cause rigidity and other features of parkinsonism.

How many people have it?

One in 1000 in the UK, rising to 1 in 200 at 70 years of age. At any one time there are over 100,000 people with the condition in the UK. Parkinson's disease occurs worldwide in all ethnic groups but is slightly more common in Caucasians. Men and women are affected equally often.

Age at onset

Onset under 40 years of age is uncommon. Approximately 10% of people with the condition are diagnosed before the age of 50 years. Most are aged around 55 years or more when they first experience symptoms.

Cause

The underlying cause of Parkinson's disease is unknown. Some people may inherit a genetic susceptibility which, combined with other factors (e.g. toxins), may make them more likely to develop the disease. Parkinson's disease does not seem to be caused by a virus or by any other infectious agent. Parkinsonism, however, has several possible causes:

• drugs, especially those used to treat some psychiatric conditions or those used to treat nausea and dizziness
• strokes
• poisoning, e.g. by carbon monoxide, manganese
• some rare conditions causing degeneration of nerve tissue
• head injury (punch-drunk syndrome)
• brain tumour.

What are the signs of Parkinson's disease?

There is no specific test for Parkinson's disease. In 70% of people, trembling of a limb leads them to consult their doctor. The four principal signs of Parkinson's disease are:

• trembling (tremor)
• rigidity causing muscle pain and stiffness
• slowness of movement
• difficulty with posture or balance.

Early clinical diagnosis of Parkinson's disease can be difficult. It is common for doctors to mistake a variety of postural tremors (trembling) for Parkinson's tremor, and vice versa, so neurological consultation is usually necessary. If the family doctor suspects Parkinson's disease or parkinsonism, he or she will refer the person to a specialist for further neurological assessment and to rule out a reversible cause of parkinsonism. Blood tests may be requested and a computed tomography (CT) scan or magnetic resonance imaging (MRI) may also be performed, when available. A nuclear medicine brain scan (single photon emission computed tomography - SPECT, or positron emission tomography - PET) can be useful in resolving any uncertainty in the diagnosis of this condition. This method can confirm or refute the presence of a degree of striatal dopamine terminal dysfunction consistent with a diagnosis of a parkinsonian syndrome, the most common of which is Parkinson's disease. In particular, it can be used to differentiate parkinsonian syndromes from essential tremor (ET), a more benign condition which is one of those most often misdiagnosed as Parkinson's disease.