Document resource
Parkinson’s disease (PD) is a multifactorial disease involving genetic susceptibility and environmental factors (eg, with increased risk associated with traumatic brain injury and decreased risk with physical activity). 1 2 Early onset PD has been recently defined as a clinical entity with people presenting with PD between the ages of 21–50 years and a genetic risk may be more important in this group than in sporadic late-onset PD.3