While Parkinson's is often considered an older persons condition and the average age of diagnosis is early 60's, many people younger than this are living with Parkinson's.
In fact, approximately 10% of people diagnosed with Parkinson's are under the age of 40.
In rare instances, Parkinson's-like symptoms can appear in children and teenagers. This form of the disorder, called juvenile Parkinsonism, is viewed as a distinct disorder, which often is genetically determined. Juvenile Parkinsonism usually has a different course and treatment options than the typical later-life Parkinson's Disease.
Because Parkinson's can be often overlooked as a diagnosis in younger patients, it is thought that the number of cases occurring in individuals under 60 may actually be much higher than currently estimated.

With the advent of new drugs that may have neuro-protective benefit and slow the progression of the disease, it is important that an accurate diagnosis be made as soon as possible, particularly for younger people.
When Parkinson's disease is seen in individuals under the age of 40, it is called young-onset or early-onset Parkinson's Disease.

As is the case of older-onset Parkinson's disease, the speed and severity of the progression of young-onset Parkinson's disease can vary greatly among individuals. Although the neuropathology and most clinical symptoms are the same at whatever age Parkinson's disease develops, the psychological, social, and medical management implications are very different for people with young-onset Parkinson's.
Parkin mutations are believed to cause young-onset PD, with symptoms beginning usually in the 40s – see Genetic Factors.