There is no test that can tell you whether you have Parkinson's.
To diagnose the disease, your doctor will probably:
If you are young, your doctor may do some blood tests to rule out other, rarer diseases.
If your doctor thinks you may have Parkinson's disease, they should refer you to a specialist (this doctor could be a geriatrician or a neurologist). You should be seen by a specialist before treatment with drugs is started.
The National Institute for Health and Clinical Excellence (NICE), which advises the government on which treatments work best, says Parkinson's disease must only be diagnosed by a specialist, not by a GP. You should see a specialist within six weeks if your symptoms are mild, or two weeks if your symptoms are severe.
The specialist may recommend you have a brain scan, such as MRI. Scans provide images of the inside of your brain to help your doctor rule out other problems or diseases. Different types of brain scan give different information.
These use magnetism to take pictures of your brain. They are good at showing up damaged areas. The results of these scans can help doctors decide if you have Parkinson's or if you've had something else (like a stroke, for example). You lie still inside the scanner. It looks like a large tube and is quite noisy. Tell the staff if you don't like enclosed spaces as they can help you. For example, they may give you a panic button to hold in your hand during the scan. If you're feeling too panicky to stay in the scanner, you press the button and the staff will let you out.
PET (Positron Emission Tomography)
These scans use injections of radioactive chemicals to show how well different parts of your brain are working. They can help doctors tell if you have Parkinson's or another brain disease. Having a PET scan doesn't hurt. You'll have a small injection and then wait for the radioactive chemical to get to your brain. You'll then be asked to lie very still in the scanning machine while the pictures are taken. You will only be exposed to a very small amount of radioactivity, and it doesn't last long. So it isn't dangerous.
SPECT (Single Photon Emission Tomography)
This is very similar to PET, but it uses different radioactive substances. These scans can also help doctors decide if you have Parkinson's or something else.
Guidelines for doctors from NICE say that doctors should usually diagnose Parkinson's disease from your symptoms. It says that SPECT scanning may be useful for some patients, but that mostly scanning is not necessary.