For decades, estimates on the prevalence of Parkinson’s disease were based on a study from 1978. Advances in clinical knowledge and data gathering helped the Parkinson’s Foundation compile new estimates on Americans living with the disease.

Among other findings, the study revealed that 572 out of 100,000 people (930,000 total) will have Parkinson’s in 2020, compared with 301 out of 100,000 (or 400,000 total) based on the older model. Foundation leaders hope the data will help inform future research and funding decisions.