The racial breakdown of Parkinson’s disease has appeared to remain consistent for years: Older white men are much more likely to have the movement disorder than any other group, multiple studies have shown.
But experts say those numbers may be misleading, and that a dearth of people of color in Parkinson’s studies, along with missed or delayed diagnoses, less access to high-quality health care and other factors could mean the gap is a lot smaller than it seems — if a gap exists at all.
Dr. Adena Leder, a neurologist and director of the Parkinson’s program at the New York Institute of Technology in Old Westbury, said some primary care doctors and neurologists may fail to diagnose people of color, women and younger white men with Parkinson’s because of incorrect assumptions about who gets the disease.
“If you don’t fit what [doctors] think is the patient demographic — meaning an older white man — then a young African American woman or a Latina woman from Honduras, they are just dismissed,” she said. “Many of these patients have already seen five other doctors before they see me.”
WHAT TO KNOW
- Studies have long shown that older white men are much more likely to have Parkinson’s disease than any other group. But experts say those numbers may be misleading, and it’s unclear how big the gap is or whether it exists.
- A key reason for the uncertainty is that most Parkinson’s research has been of affluent white men. More research is needed of people of color to determine whether there are racial differences, experts say.
- Some doctors’ perception of Parkinson’s as primarily a disease of older white men means that some may fail to diagnose people of color, women and younger white men with the disease, a leading Long Island Parkinson’s expert said.
Parkinson’s disease is a brain disorder that can lead to uncontrollable shaking or other movements, trouble with balance and coordination, difficulties walking, problems speaking and other symptoms.
There are nearly a million people in the United States living with Parkinson’s, according to the Parkinson’s Foundation. It’s most common in older adults, but about 5% to 10% of people develop the disease before age 50, according to the National Institute on Aging.
A seminal 2010 study analyzing Medicare records of 450,000 people 65 and older found that white men were much more likely to have the disease than Black and other nonwhite men and women: 2,168 cases per 100,000 people for white men, versus 1,265 for Black men.
But the gap in newly diagnosed cases was less than half as big: 560 per 100,000 for white men, compared with 427 for Black men. That’s a 31.1% difference, versus the 71.4% difference in the overall rate.
The gap in newly diagnosed cases also was narrower between white men and every other racial group, and between white men and white women, the study found.
Dr. Allison Willis, an associate professor of neurology and epidemiology at the University of Pennsylvania and lead author of the study, said “we really don’t know” why there are such differences, and more research is needed.
Dr. Rebecca Gilbert, chief scientific officer for the Staten Island-based American Parkinson Disease Association, said the differences may be in part because of later diagnoses of people of color. Black patients in particular may have a greater distrust of the medical system, which could lead them to seek care later, she said. They’re also less likely to have a primary care physician, she said.
Rosa Peña, the association’s vice president of programs and services, said financial barriers may prevent some people of color from getting to a specialist who may diagnose them.
The Rev. Roderick Pearson, 60, a Black man diagnosed with Parkinson’s in 2015 and pastor of St. Mark Remnant Ministries in Bay Shore, said the later diagnoses may be in part due to disparities in health care as well as socio-economic factors.
Even after getting diagnosed, “the problem is the availability of resources and the ability to afford” proper care, he said.
After diagnosis, 'The problem is the availability of resources and the ability to afford' proper care.
-Rev. Roderick Pearson, here with his wife, Michelle. Pearson was diagnosed with Parkinson’s in 2015.
Credit: Newsday/ J. Conrad Williams Jr.
Willis said it’s unclear whether older white men really have a significantly higher rate of Parkinson’s, or whether their higher numbers reflect a greater likelihood of being diagnosed. For someone to show up in Parkinson’s data, they first must be diagnosed with the disease, she said.
A key reason for the uncertainty over how much of a gap, if any, really exists is that research on Parkinson’s has overwhelmingly been of white men — and particularly of wealthier, highly educated white men, Willis said.
“Understanding whether and if, and why, there are race differences in Parkinson’s disease is going to require us sampling much more broadly,” she said, adding that in the past year or two there has been more funding and interest in studying people of color with Parkinson’s.
The American Parkinson Disease Association has increased its funding for research into racial disparities in the past few years, and it convened a conference in 2019 to discuss the issue and plans another next year, Gilbert said.
Gilbert said there is a “vicious cycle” in research, because if Black people are less likely to be diagnosed with Parkinson’s by a primary care physician, “then you’re not seeing the movement-disorder specialists who have access to the clinical trials.”
People with Parkinson’s who see movement-disorder specialists tend to have better outcomes, said Dr. Chantale Branson, a neurologist with Morehouse Healthcare in Atlanta and an assistant professor of neurology at the Morehouse School of Medicine.
The cause of Parkinson’s is still unknown, but the focus of research on white men also has hindered the search for the origin of the disease, Willis said.
Genes that are linked with Parkinson’s are common in European populations, including in people with red hair, she said.
‘What we know about genetic risk factors for Parkinson's disease is in part influenced by the fact that we have primarily studied only Caucasian groups’
-Dr. Chantale Branson, neurologist and assistant professor of neurology at the Morehouse School of Medicine
Credit: Tamaron Johnson, Morehouse School of Medicine.
But, she added, “What we know about genetic risk factors for Parkinson's disease is in part influenced by the fact that we have primarily studied only Caucasian groups of people in Parkinson's gene studies. So there may be other genetic risk factors for Parkinson's that are common in individuals who have primarily Asian ancestry, primarily African ancestry. And we don't really know right now, because we haven't really studied those groups equally.”
Environmental factors, including exposure to pesticides, are among other possible causes, she said.
Branson is preparing to submit for publication findings of a study she led at a public hospital in Atlanta that found a higher rate of Parkinson’s among low-income Black patients compared with the nationwide average for Black people. One potential reason could be greater exposure to certain contaminants, she said.
Gilbert said when she saw patients at NYU Langone Health and the publicly run Bellevue Hospital in Manhattan, she was struck by how the Parkinson’s patients at Bellevue were in more advanced stages of their diseases — as was the case with other conditions. A low-income person is more likely to fall through the cracks and not have a doctor who refers them to a movement-disorder specialist who can diagnose them with Parkinson’s, she said.
Leder said an early diagnosis is critical, because exercise helps prevent the progression of the disease. People with good insurance have more access to physical therapy and exercise programs, she said.
The American Parkinson Disease Association is developing exercise, wellness and other programs targeted toward people of color and Spanish-speaking people, Peña said.
The organization also is increasing outreach in communities of color, working with trusted institutions like community centers, senior centers, neighborhood clinics and churches, she said. The aim is both to get people of color who have Parkinson’s symptoms to see a specialist for a potential diagnosis, and to connect those already diagnosed with services, she said.
The association’s expanded outreach came out of focus groups over the past few years with people of color on Long Island and elsewhere, she said.
Pearson’s participation in an association focus group at NYIT led to a support group for people of color with Parkinson’s that he now wants to expand to everyone.
It helps to talk with others with Parkinson’s, he said.
“Whether you’re Black or white, people don’t understand your symptoms,” he said. “They don’t understand why you aren’t able to move, the freezing, how your legs are cemented to the ground, how you can be fully functional and 10 minutes later not being able to raise your arm. It’s such a hard disease.”