Parkinson’s disease (PD) is the second most common neurodegenerative disorder after Alzheimer’s disease and affects over 6 million people around the world. Both the prevalence and incidence of PD increase with age, peaking in the 70 and 80-year-old age groups. Evidence suggests there is a higher prevalence and incidence of PD in western countries compared with eastern countries, with men slightly more affected compared with women.