Parkinson’s disease causes slowness of movement, a particular pattern of tremor, muscle stiffness, and imbalance. The diagnosis is based on a patient’s history and physical examination. Parkinson’s disease needs to be distinguished from other parkinsonian disorders (that may look similar to Parkinson’s disease, but are not actually Parkinson’s disease), and this distinction is not always obvious early in the disease course. Parkinson’s disease usually starts slowly and progresses gradually. Onset of symptoms is usually after age 50 years. Remaining physically active helps a person’s level of function. The initial treatment for Parkinson’s disease includes medications. If those fail, then some patients may be candidates for invasive treatments such as deep brain stimulation. A general neurologist or a movement disorders specialist usually diagnoses and manages Parkinson’s disease.