As of 2015, no tests are available to diagnose Parkinson's disease, states Mayo Clinic. Diagnosis usually involves reviewing an individual's medical history and symptoms and performing a physical and neurological examination.
Sometimes, diagnosing Parkinson's disease takes several visits to give medical professionals time to evaluate the condition, explains Mayo Clinic. Neurologists may also order tests to rule out other diseases that could be causing symptoms.
Another way a medical professional can diagnose Parkinson's disease is by administering a drug called carbidopa-levodopa. If a person shows significant improvement in symptoms, it's often enough for a neurologist to confirm the diagnosis. The patient is usually given a full dose on an empty stomach, at least one hour before eating.