Main samples PD table
| Publication | Definition | Age of onset in years (SD) | Duration of illness in years (SD) |
| Asami 2009... | Individuals with PD | 33.80 (10.30) | 3.90 (3.40) |
| Hayano 2009... | Individuals with PD | 32.80 (10.20) | 5.40 (6.40) |
| Massana 2003... | Individuals with PD | N/A | N/A |
| Uchida 2008... | Individuals with PD | 29.74 (9.83) | 8.34 (6.01) |
| Yoo 2005... | Individuals with PD | 29.70 | 3.60 (2.20) |