How Do Doctors Diagnose Parkinson's Disease?

Medically Reviewed by Carol DerSarkissian, MD on August 27, 2021
4 min read

Maybe some of the things you do every day aren’t as easy as they used to be. Perhaps you’re having trouble buttoning your shirt or brushing your teeth, or your sense of smell isn’t up to snuff. Are these changes part of getting older or possibly signs of a health problem like Parkinson’s disease?

The answer isn’t always clear, because there’s no specific test for Parkinson’s disease. Doctors usually make the diagnosis based on your symptoms and an exam.

If you have at least two of these main signs, your doctor will want to find out if Parkinson’s disease is the reason behind them:

  • Tremor or shaking
  • Slow movement (called bradykinesia)
  • Stiff or rigid arms, legs, or trunk
  • Balance problems or frequent falls

Symptoms usually start on one side of your body and eventually move to the other side.

Signs of Parkinson’s disease can look a lot like those of other conditions that affect your nervous system. So it can sometimes take a while to know for sure what’s going on, especially if your symptoms are mild.

If your doctor thinks you might have Parkinson’s disease, theyll recommend that you see a specialist who works with nervous system issues, called a neurologist. One who’s also trained in movement disorders, like Parkinson’s, may be able to make the right diagnosis faster.

Your neurologist will probably want to see how well your arms and legs move and check your muscle tone and balance.

They may ask you to get out of a chair without using your arms for support, for example. They also may ask a few questions:

  • What other medical conditions do you have now or have you had in the past?
  • What medications do you take?
  • Has your handwriting gotten smaller?
  • Do you have trouble with buttons or getting dressed?
  • Do your feet feel “stuck” to the floor when you try to walk or turn?
  • Do people say your voice is softer or your speech is slurred?

Tell your doctor if you’ve noticed a change in your sense of smell or you have trouble with sleep, memory, or mood.

Parkinson’s disease can look different from person to person. Many people have some symptoms and not others.

Your doctor may want to start by testing your blood or doing a brain scan to rule out other conditions.

People who have Parkinson’s disease don’t make enough of a brain chemical called dopamine, which helps you move. If those first tests don’t show a reason for your symptoms, your doctor may ask you to try a medication called carbidopa-levodopa, which your brain can turn into dopamine. If your symptoms get much better after you start the drug, your doctor probably will tell you that you have Parkinson’s disease.

If the medication doesn’t work for you and there’s no other explanation for your issues, your doctor might suggest an imaging test called a DaTscan. This uses a small amount of a radioactive drug and a special scanner, called a single photon emission computed tomography (SPECT) scanner, to see how much dopamine is in your brain. This test can't tell you for sure that you have Parkinson's disease, but it can give your doctor more information to work with.

It can take a long time for some people to get a diagnosis. You may need to see your neurologist regularly so they can keep an eye on your symptoms and eventually figure out what’s behind them.

Here are some possibilities:

Side effects of medication: Certain drugs used for mental illnesses like psychosis or major depression can bring on symptoms like the ones caused by Parkinson’s disease. Anti-nausea drugs can, too, but they typically happen on both sides of your body at the same time. They usually go away a few weeks after you stop taking the medication.

Essential tremor: This is a common movement disorder that causes shaking, most often in your hands or arms. It’s more noticeable when you’re using them, like when you eat or write. Tremors caused by Parkinson’s disease usually happen when you’re not moving.

Progressive supranuclear palsy: People with this rare disease can have problems with balance, which may cause them to fall a lot. They don’t tend to have tremors, but they do have blurry vision and issues with eye movement. These symptoms usually get worse faster than with Parkinson's disease.

Normal pressure hydrocephalus (NPH): This happens when a certain kind of fluid builds up in your brain and causes pressure. People with NPH usually have trouble walking, a loss of bladder control, and dementia.

About 25% of people who are told they have Parkinson’s disease don’t have it. If you’re diagnosed with it, you might want to see a movement disorder specialist, especially if you went to a general neurologist first.