How is Parkinson's diagnosed?

Current evidence suggests that Parkinson’s tends to develop gradually. It may be many months, even years, before the symptoms become obvious enough for someone to go to the doctor.

This information looks at what parkinsonism is, how Parkinson’s and other similar conditions may be diagnosed, and explains some of the tests that may be involved in the process.

Parkinsonism is a term used to describe symptoms or signs that are found in Parkinson’s, but which can also be found in other conditions that cause slowness of movement, stiffness and tremor.

Most people with a form of parkinsonism have idiopathic Parkinson’s disease, also known as Parkinson’s. Idiopathic means the cause is unknown. 

Other less common forms of parkinsonism include multiple system atrophy (MSA), progressive supranuclear palsy (PSP), drug-induced parkinsonism and vascular Parkinson’s.

If you’re concerned about symptoms you’ve been experiencing, you should visit your GP. If your GP suspects you have Parkinson’s, clinical guidelines recommend they should refer you quickly to a specialist with experience in diagnosing the condition (and not try to treat you themselves).

It’s not always easy to diagnose the condition. So it’s important that you see a Parkinson’s specialist to get an accurate diagnosis and to consider the best treatment options.

Diagnosing Parkinson’s can take some time as there are other conditions, such as essential tremor (see ‘How long will it take to get a diagnosis of Parkinson’s?’), with similar symptoms. There is also currently no definitive test for diagnosing Parkinson’s.

Investigating symptoms

Parkinson’s should only be diagnosed after having a consultation with a specialist. A Parkinson’s specialist will take a detailed medical history and examine you. You may find it helpful to keep a diary or record of your symptoms to help you explain what’s been happening.

Parkinson’s can cause many symptoms and these can vary from person to person.

Typical symptoms of Parkinson’s include slowness of movement (bradykinesia), tremor, difficulty turning over in bed, fatigue and a tendency to have small handwriting.

Typical early symptoms include a reduced sense of smell, depression, anxiety, tiredness, disturbed sleep and constipation.

Looking for signs of Parkinson’s

Your specialist will examine you to look for common signs of Parkinson’s. You may be asked to:

  • write or draw – to see if your writing is small or gradually fades
  • walk – to see whether there’s a reduction in the natural swing of your arm or in your stride length and speed
  • speak – to see if your voice is soft or lacks volume

The specialist will also look at and ask you about your:

  • face – to see if there is a ‘masked’ look or if you have difficulty with facial expressions
  • limbs – to see if you have a tremor, any stiffness (rigidity) or slowness of movement

As well as examining you for any of the typical signs of Parkinson’s, the specialist will also look for signs that may suggest a different diagnosis.

It may be helpful to take someone with you for support when seeing a specialist. Taking a list of questions you want to ask can also be useful so you don’t forget to mention something you want to know about. If a healthcare professional says something you don’t understand, don’t be afraid to ask them to explain what they mean.

Response to Parkinson’s drugs

After examining you, and depending on the severity of your symptoms, your specialist may suggest you take medication for Parkinson’s. If your symptoms improve after taking Parkinson’s medication for a few weeks or months, your specialist may confirm a Parkinson’s diagnosis. However, some people with other forms of parkinsonism will also respond well to these drugs. 

Your specialist may suggest you have a scan to help make a diagnosis. However, scans alone can’t make a definite diagnosis of Parkinson’s, so they are not commonly used.

MRI or CT scans

These are brain-imaging scans and can tell your specialist what the structure of your brain looks like. Brain scans of people with Parkinson’s usually look normal, but they can be helpful in diagnosing other types of parkinsonism – the scan may not look normal in some of the rarer forms.


These are scans that can tell your specialist how different areas of the brain are working. SPECT is a type of imaging test that shows how blood flows to tissues (muscles, for example) and organs. A certain type of SPECT scan is regularly used to help specialists confirm the loss of a particular type of brain cell containing a chemical called dopamine. This type of scan is known as a dopamine transporter scan or DaTSCAN. It’s the loss of these dopamine-producing cells that causes the development of Parkinson’s. But similar loss may also occur in some other rarer neurological conditions. So an abnormal DaTSCAN result cannot give a definitive diagnosis of Parkinson’s, but in most cases it is due to Parkinson’s. 

A normal DaTSCAN can be helpful in showing that a person’s symptoms, particularly tremor, are not caused by Parkinson’s, but may be due to another condition, for example, essential tremor.

What is essential tremor, and how is it different to a Parkinson’s tremor?

A tremor is a rhythmical, involuntary movement that affects a part of the body, such as the hand.

Essential tremor is the most common type of tremor. It’s most noticeable when your hands are doing something and it usually affects both the right and left sides of the body equally. Essential tremors often lessen when your body is resting. 

Unlike an essential tremor, a Parkinson’s tremor is most obvious when the affected body part is resting and tends to be less noticeable with movement. It usually starts on one side of the body and may progress to the other side as Parkinson’s develops.

The time it takes to get a diagnosis can vary from person to person. Some people may receive a diagnosis of Parkinson’s quite quickly, but for others it may be a long process. This can be due to a number of things, including your medical history, your age and what symptoms you have.

Your specialist may wish to rule out other causes of your symptoms first and see how you respond to treatment. This may take some time, and, as already mentioned, there is currently no definitive test for Parkinson’s.

How you respond to treatment may help your specialist make a diagnosis. Keeping a diary or record of your symptoms will give the specialist more information to guide their decision.

If you’re waiting for a diagnosis and have any questions, you can call our helpline on 0808 800 0303. You can also speak to others who are currently being diagnosed, or have already gone through a similar experience, on our online forum.

Because the symptoms of Parkinson’s are sometimes similar to other forms of parkinsonism, people can sometimes be misdiagnosed. 

It’s difficult in the early stages to be certain what type of parkinsonism someone has. However, as time goes on, depending on what symptoms you have and your response to Parkinson’s medication, a specialist may be able to offer a more accurate diagnosis.

As there’s currently no definitive test for Parkinson’s, some experts prefer to use the term parkinsonism when diagnosing people. They may only specifically diagnose Parkinson’s if they see your condition following the typical pattern. 

Researchers are currently exploring new and different ways to diagnose and monitor Parkinson’s more accurately. These include looking at skin cells and blood samples to spot tiny but significant changes, and developing new and more sensitive imaging techniques, such as ultrasound. 

Other research areas include whether some of the very early symptoms of Parkinson’s, such as problems with sense of smell, can be detected using tests such as scratch and sniff tests, sniffer dogs and looking for other chemical markers of the condition in the blood. 

It’s difficult to say how long it will be before new and better tests for diagnosing Parkinson’s become available, but research in this area is a major focus for Parkinson’s UK.

Find out more about our research.

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"Getting a diagnosis wasn’t easy, but I’m learning more every day and gradually adapting to life with Parkinson’s."

Daxa shares the 3-year journey she had to receive a Parkinson's diagnosis – and how she's gradually learning to adapt to the challenges.

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Last updated

Next update due 2023 

If you'd like to find out more about how we put our information together, including references and the sources of evidence we use, please contact us at [email protected]