In diagnosing Parkinson’s disease, a physician will compile a thorough medical history and perform a complete physical examination. To date, no blood tests or other laboratory tests have been shown to accurately diagnose Parkinson’s disease.

While diagnosis may be difficult, a neurological examination may provide clues to the presence of the illness. The physician will also look for at least two of the following three signs: tremor when the patient is at rest, slowness of movement (bradykinesia) or rigidity. Various tests can be used to reveal the presence of these symptoms. For example, patients may be asked to tap a finger and thumb together or tap their foot to look for signs of bradykinesia. Meanwhile, postural instability is tested by asking patients to retain their balance while they are pulled backwards by the physician.

Physicians may recommend a brain scan, using imaging technology such as magnetic resonance imaging (MRI), to rule out other conditions that can cause similar symptoms.

Parkinson’s disease is diagnosed when a combination of a patient’s medical history, symptoms and test results indicate illness that cannot be explained by other factors or diseases.