Parkinson's Disease

What is Parkinson's disease?

Parkinson's disease is a condition in which parts of your brain become progressively damaged over many years, causing you to have less of a chemical called dopamine. Dopamine helps your brain control smooth, purposeful movement, so a shortage of it is responsible for many of the condition's symptoms.

What are the symptoms of Parkinson's disease?

Symptoms usually develop gradually and are mild at first, often starting on one side of the body. The three main symptoms affect physical movement:

• Tremor: Shaking, usually starting in the hand or arm, most noticeable when the limb is relaxed and resting
• Slowness of movement (bradykinesia): Everyday tasks take longer, and you may develop a slow, shuffling walk with small steps
• Muscle stiffness (rigidity): Tension in your muscles that can make it harder to move and can cause painful cramps.

You may also develop a wide range of other symptoms, including:

• balance problems, which can increase your risk of falling
• loss of your sense of smell, sometimes years before other symptoms appear
• constipation, and problems with your bladder
• sexual difficulties
• dizziness or fainting when you stand up, caused by a sudden drop in blood pressure
• excessive sweating
• swallowing difficulties, drooling, or changes to your speech
• problems sleeping
• depression, anxiety, and memory or thinking problems.

What are the causes of Parkinson's disease and who is at risk?

Parkinson's disease is caused by a loss of nerve cells in a part of the brain called the substantia nigra. These cells produce dopamine, a chemical that helps your brain send messages to control smooth, purposeful movement. By the time symptoms appear, most people have already lost 60% to 80% or more of these dopamine-producing cells.

Exactly why these nerve cells are lost isn't clear, but experts think it's due to a combination of genetic and environmental factors. You may be more likely to develop Parkinson's disease if you:

• are over 50, though a small number of people develop it before 50 (sometimes called early-onset Parkinson's)
• are male, as men are slightly more likely to be affected than women
• have a close relative with the condition
• have been exposed to certain pesticides or pollutants, for example through farming or landscaping work.

Are there different types of Parkinson's disease?

Parkinson's disease is the most common form of a wider group of conditions called parkinsonism, which share similar symptoms.

• Atypical parkinsonism (sometimes called Parkinson's-plus syndromes): This includes conditions such as multiple system atrophy, Lewy body dementia, progressive supranuclear palsy, and corticobasal degeneration. These cause additional symptoms alongside those of Parkinson's, and often don't improve with the medicine levodopa.
• Early-onset Parkinson's disease: This is when symptoms begin before the age of 50.
• Juvenile parkinsonism: This is a very rare form that can appear in people under 20, which usually does improve with levodopa.

How is Parkinson's disease diagnosed?

There's no single test that can definitively diagnose Parkinson's disease. Instead, your doctor will refer you to a neurologist, who will:

• take a detailed medical history and carry out a neurological examination, looking for the physical signs of Parkinson's disease
• arrange blood or other laboratory tests, to check for other conditions and look for biological markers that can help support a diagnosis
• arrange brain imaging, such as an MRI or a specialised scan called a DaT scan, mainly to rule out other conditions
• consider genetic testing, if an inherited form of the condition is suspected.

How is Parkinson's disease treated?

Non-surgical treatment

There's no cure for Parkinson's disease, but treatments can help control your symptoms and maintain your quality of life. You may not need treatment in the early stages if your symptoms are mild, though you'll still have regular check-ups with your specialist.

Supportive therapies can include:

• Physiotherapy: To ease muscle stiffness and improve your walking, flexibility and fitness
• Occupational therapy: To help with everyday tasks and make sure your home is safe and set up for you
• Speech and language therapy: If you have swallowing or speech difficulties
• Advice from a dietitian: For example to manage constipation or low blood pressure

Medication is used to improve your main symptoms, such as tremor and slow movement. The main types are:

• Levodopa: The medicine most people with Parkinson's eventually need. It's converted into dopamine in your brain and usually works very well at first, though its effects can become less reliable over the years, and long-term use is linked to uncontrollable, jerky movements (dyskinesia)
• Dopamine agonists: These act as a substitute for dopamine, with a milder effect than levodopa. They can cause side effects including nausea, sleepiness, hallucinations, and in some people, compulsive behaviours such as gambling
• Monoamine oxidase-B (MAO-B) inhibitors: These block the breakdown of dopamine, and are sometimes used as an alternative to levodopa in early Parkinson's
• Catechol-O-methyltransferase (COMT) inhibitors: These are used in later stages to help levodopa last longer.

Your specialist will discuss the risks, benefits and side effects of each option with you, and will review your medication regularly as your needs change.

Surgical treatment

Deep brain stimulation is a type of surgery used for some people with Parkinson's disease when medication is no longer controlling symptoms well, or is causing difficult side effects.

A surgeon implants a small pulse generator, similar to a heart pacemaker, connected to fine wires placed in the part of your brain affected by Parkinson's. This sends a tiny electric current that can ease symptoms, although it doesn't cure the condition and isn't suitable for everyone.

When should I see a doctor?

See a GP if you're concerned that you might have symptoms of Parkinson's disease, such as a tremor, slow movement or stiffness. They'll ask about what you're experiencing and may refer you to a neurologist for further tests.