Diagnosing Parkinson's disease is difficult, especially early in the disease. No single test can provide a diagnosis. A diagnosis will involve your doctor speaking to you about your symptoms and doing a physical examination. Your doctor might also see if you respond to medicine that increases dopamine levels in your brain. You may need brain scans to rule out other conditions that could cause your symptoms. These could include MRI and CT scans or others. Your doctor may also refer you for blood tests to check for other illnesses.