Information for Diagnosis
Specifically, diagnosing PD
- There isn’t a specific test to diagnose Parkinson’s disease. A doctor trained in nervous system conditions (neurologist) or a neurologist with a specialty in movement disorders will diagnose Parkinson’s disease based on your medical history, a review of your signs and symptoms, and a neurological and physical examination.
- Your doctor may suggest a specific single-photon emission computerized tomography (SPECT) scan called a dopamine transporter (DAT) scan. Although this can help support the suspicion that you have Parkinson’s disease, it is your symptoms and neurological examination that ultimately determine the correct diagnosis. Most people do not require a DAT scan.
- Your health care provider may order lab tests, such as blood tests, to rule out other conditions that may be causing your symptoms.
Imaging tests — such as an MRI, ultrasound of the brain and PET scans — also may be used to help rule out other disorders. Imaging tests aren’t particularly helpful for diagnosing Parkinson’s disease.
- In addition to your examination, your health care provider may give you carbidopa-levodopa (Rytary, Sinemet, others), a Parkinson’s disease medication. You must be given a sufficient dose to show the benefit, as low doses for a day or two aren’t reliable. Significant improvement with this medication will often confirm your diagnosis of Parkinson’s disease.
- Sometimes it takes time to diagnose Parkinson’s disease. Health care providers may recommend regular follow-up appointments with neurologists trained in movement disorders to evaluate your condition and symptoms over time and diagnose Parkinson’s disease.
More information on diagnosis:
There is no single definitive test for diagnosing PD in a living person and there is no way to track disease progression on a biological level. Aside from finding a cure, the holy grail of PD research is the discovery of biomarkers — detectable and measurable changes in the body that can be used to predict, diagnose, and monitor disease activity and progression. Biomarkers can be identified through a number of different methods, including imaging scans (e.g., MRI, CT), biological samples (e.g., cerebrospinal fluid, plasma), and genetic studies. The risk for heart disease, for example, can be detected by measuring cholesterol or blood pressure. People at risk for PD currently lack a similar means for risk detection.
The ideal PD biomarker would be one that can be easily tested, varies with disease severity, and is abnormal during the preclinical phase of the illness before a person has any symptoms. Reliable biomarkers would allow physicians to screen and identify people at increased risk of developing PD and more accurately monitor disease progression among people who have been diagnosed with the disease.
Biomarkers would also greatly accelerate clinical research efforts by shortening the timeframe needed to show that a drug has successfully engaged a disease-specific target in the brain or nervous system. Such measures may be available long before meaningful clinical changes are evident after a person has tried a particular therapy or intervention. Biomarkers may also be useful for determining optimal drug dosage.