Incidence of Parkinson’s disease 50% higher than previously thought

The annual incidence of Parkinson’s disease was 50% higher than previous estimates in data from five epidemiological cohorts in the United States and Canada.

The new incidence rate was nearly 90,000 cases per year for people age 65 and older, reported Allison Willis, MD, of the University of Pennsylvania in Philadelphia, and co-authors..

This contrasts sharply with the previous incidence rate of 40,000 to 60,000 new cases per year based on smaller studies, the researchers wrote in npj Parkinson’s disease.

Not surprisingly, as the primary risk factor for Parkinson’s disease is age, incidence rates increased with age throughout the study. At all ages, the incidence was higher in men than in women.

In the United States, a group of counties with a higher incidence of Parkinson’s has emerged in the juxtaposition of the Midwestern and Southern regions of the country. Incidence rates were also high in southern California, southeast Texas, central Pennsylvania and Florida. The Parkinson’s disease belt first spotted in 2005 has persisted in the data.

“Unique to this study, we found that estimates of the incidence of Parkinson’s disease varied for many reasons, including how cases are identified and the geographic location of the study,” Willis said in a statement. communicated.

“The persistence of the Parkinson’s disease belt in the United States could be due to population, health care, or environmental factors,” she noted. “Understanding the source of these variations will be important for health care policy, research and care planning.”

Willis and colleagues identified the incidence of Parkinson’s disease in a common year – 2012 – in five cohorts, using data from the US Medicare program, Ontario Health Care in Canada, Kaiser Permanente North California, Honolulu- Asia Aging Study and Rochester Epidemiology Project in Olmsted County, Minnesota. Verification and diagnostic criteria included new documentation of symptoms of Parkinson’s disease or diagnosis of Parkinson’s disease in 2012.

The researchers calculated the age- and sex-adjusted incidence of Parkinson’s disease in people aged 65 and over for each data set, then repeated the analyzes for people aged 45 and over in three datasets (Ontario Health Care, Kaiser Permanente and Rochester Epidemiology) that regularly captured information. on the youngest.

The five cohorts contained data for 6.7 million person-years of adults 45 and older and 9.3 million person-years of those 65 and older.

For the elderly, the adjusted incidence estimates ranged from 108 to 212 per 100,000. For men, these estimates were from 162 to 277 per 100,000; among women, they were 66 to 161 per 100,000. For people aged 45 and over, estimates ranged from 47 to 77 per 100,000 and were higher among men.

The incidence varied across cohorts, in part due to case ascertainment and diagnostic methods. Other factors — including the prevalence of genetic risk factors in certain populations or exposure to environmental toxins in certain locations — may also have played a role, the researchers noted.

Limitations of the study included possible confounding, misclassification and selection bias, Willis and colleagues acknowledged. Estimates for the current year could be higher due to lower prevalence of smoking, increased prevalence of certain hazards like pesticides and greater recognition of symptoms of Parkinson’s disease, they suggested.

A 2018 prevalence study estimated that about 930,000 people in the United States had Parkinson’s disease in 2020. That figure is expected to climb to 1,238,000 in 2030, according to Census Bureau population projections.

Willis and his colleagues suggested that their findings could help inform clinical trial strategies and shed light on “hot spots” in Parkinson’s disease where more resources might be needed.

“The growth in the number of people diagnosed with and living with Parkinson’s disease underscores the need to invest more in research toward better treatments, a cure, and one day, prevention,” said co-author Brian Fiske, PhD. , from the Michael J. Fox Foundation. “It’s also a clear call for lawmakers to implement policies that will reduce the burden of Parkinson’s disease on American families and programs like Medicare and Social Security.”