The results of a new study show that the incidence of Parkinson’s disease (PD), or the number of new cases diagnosed per year, is 50% higher than previously estimated. Instead of past estimates of 60,000 new cases of PD diagnosed per year, the new study determined that there are approximately 90,000 new cases of PD diagnosed in the US per year.

In addition, the study looked at the geographical variation of diagnoses and found a higher incidence of PD in certain areas of the Midwest and South, as well as in southern California, southeastern Texas, central Pennsylvania, and Florida.

This current finding builds on past work that updated the estimates of the prevalence of PD, or the total number of people diagnosed in a population. About four years ago, a crucial study determined the prevalence of PD to be approximately one million in the United States. The study estimated that the prevalence will increase to 1.3 million by 2030, which aligns with an increase in the incidence, or the number of cases being diagnosed.

The study results beg the question – why is the incidence so high? The answer is likely due to a number of reasons: 1) the clearest risk factor for being diagnosed with PD is age, and the population is aging, therefore more people are being diagnosed; 2) there is increased awareness of the disease, so people are more likely to go to a doctor for a symptom that in the past, may have been dismissed as normal aging. This increased engagement with the medical community can increase diagnoses as well; and 3) there may be factors in the environment that are increasing PD risk and therefore PD diagnoses. One such chemical is paraquat, a herbicide. Currently, there are efforts to advocate for a ban on paraquat in the US.

Knowing the accurate incidence and prevalence of PD are vital for the PD community. It is crucial to have accurate PD statistics since they inform lawmakers who make decisions concerning allocation of research funds about the true impact of the disease. They also inform public health officials who need to plan for the growing PD population. Currently, the National Plan to End Parkinson’s Act is working its way through both houses of Congress and if passed will unite the federal government as well as all those impacted by PD to create ways to further prevention, medical care, treatment and research for PD. Knowing the number of people in the US who have been recently diagnosed, the total number of people diagnosed, and the geographic locations of those affected, will be essential to these efforts.