Risk FactorsThe greatest risk factor for Parkinson's Disease (PD) is age. About 1-2% of adults over the age of 65 and about 0.3% of the general population have PD. PD occurs infrequently in the population under 40 years of age and early onset has been associated with the probability of genetic causes.
The role of sex as a risk factor of PD is disputed. Some studies have found women to be at higher risk for PD, while others have found men to be at higher risk, and others have found no difference. Differences between men and women may also vary by ethnicity. Studies have found associations of smoking and caffeine consumption with decreased rates of PD and head injury and pesticide exposure with increased rates.