How is Parkinson’s disease diagnosed?

Parkinson's disease is diagnosed based on a combination of clinical features and medical history.  There is no blood test or X-ray that can provide a conclusive diagnosis of Parkinson’s disease.

One’s medical history and an examination by a doctor are the most reliable ways in which one can be diagnosed with this disease. A physician may assess a patient’s muscle strength and how quickly they are able to move, along with an evaluation of such symptoms as rapid movements and tremors, and what activities cause the symptoms to appear.

Imaging tests, such as an MRI of the brain, may support the diagnosis or rule out certain conditions that have similar symptoms as those of Parkinson’s disease such as a stroke, Normal Pressure Hydrocephalus (NPH), or an abnormal buildup of cerebrospinal fluid.

A DaTscan (dopamine transporter scan), which is a type of imaging that focuses on the dopamine-producing cells, can help support a Parkinson’s diagnosis. DaTscan involves the injection of a small amount of radioactive dye to mark dopamine receptors in the brain. Once administered, doctors can use an imaging device called a single-photon emission computed tomography (SPECT) to identify reduced dopamine levels in the brain.

Clinical Features: Tremors (involuntary shaking movements), Bradykinesia (slowness of movement), Rigidity (stiffness of muscles), Postural instability (difficulty maintaining balance), and Gait disturbances (shuffling or stooped walking). 

Medical History: Onset and progression of symptoms, Family history of Parkinson's disease, and Other medical conditions that may cause similar symptoms. 

Examination: 

• Neurological exam to assess movement, reflexes, and coordination

• Review of handwriting and drawing samples

• Blood tests to rule out other conditions

Imaging Studies (Optional): 

• Brain scans (MRI or CT) to rule out structural abnormalities 

• Dopamine transporter (DaT) scan to assess dopamine levels in the brain 

It's important to note that there is no single definitive test for Parkinson's disease. The diagnosis is typically based on the presence of characteristic symptoms and the absence of other possible causes. 

Additional Considerations: 

• Early-onset Parkinson's disease (before age 50) may require genetic testing. 

• Parkinson's disease can sometimes mimic other disorders, such as essential tremor or multiple system atrophy. 

• A specialist in movement disorders (neurologist) is recommended for accurate diagnosis and management.