According to a 2021 review that examined 204 countries, high-income areas of North America had the highest increase in the prevalence of Parkinson's from 1990 to 2019. The prevalence refers to the number of people living with PD in that specific period.
The same review states that East Asia had the highest increases in PD incidence in that period. Incidence refers to the number of people who receive a new Parkinson's diagnosis.
The number of people with PD in China, in particular, increased more than in any other country between 1990 and 2019.
However, the study observed that trends of PD decreased in Mediterranean countries, including Italy and Spain. This may be due to the Mediterranean diet, which researchers link to a decreased risk for Parkinson's.