Prevalence may be 50% higher than previous estimates

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Researchers say Parkinson’s is 50% more common than previously thought, which may have implications for diagnosis and treatment. Spencer Platt/Getty Images
  • In a recent study, researchers examined health records from North America to assess the prevalence of Parkinson’s disease (DP).
  • They found that the incidence of Parkinson’s disease is 50% more common than previous estimates.
  • The findings might have implications for healthcare providers for the diagnosis and treatment of PD.

Parkinson’s disease (PD) is a degenerative neurological condition that affects movement.

It is the second most common age-related neurodegenerative condition globally and is responsible for significant disability and increased dementia and mortality risk.

Common PD symptoms include:

  • tremors
  • slow movement
  • cognitive impairment
  • sleep disorders
  • pain

There is no clear consensus on what causes PD, but age is a known risk factor. Most people with PD develop the condition later 60 years of age. While men are twice as likely to develop PD than women, women have a higher mortality rate and faster disease progression.

Understanding who might develop PD could help inform healthcare planning capacity and delivery.

In a recent study, researchers examined data from North America to estimate the rate of PD among those aged 45 and older. They found that Parkinson’s disease is 50% more prevalent than previously thought.

The study was recently published in npj Parkinson’s Disease.

For the study, researchers examined Parkinson’s incidence from 2012 healthcare data in North America. The data included cohorts of 6.7 million person-years of adults aged 45 and older and 9.3 million person-years of adults aged 65 and older.

The researchers found that 60,0000–95,000 people were diagnosed with PD in North America in 2012, significantly more than previous estimates of 40,000–60,000.

Advanced age was strongly linked to an increased rate of PD, and males were consistently more likely to develop the condition than females.

The findings also revealed that PD was more common in southern California, southeastern Texas, central Pennsylvania, and Florida. Incidence was lower in the Mountain West region, the western Midwest, and the far Northwest.

To help inform health policy, the researchers suggest an incidence rate of 62 per 100,000 people per year for those aged 45 or older. They noted that this would equate to 77,000 diagnoses in 2012 and 86,000 cases in 2020.

Dr. Jean-Philippe Langevin, a neurosurgeon and director of the Restorative Neurosurgery and Deep Brain Stimulation Program for Pacific Neuroscience Institute at Providence Saint John’s Health Center in Santa Monica, CA, not involved in the study, told Medical News Today:

“This is an important study. The authors used a robust methodology to analyze five different datasets to estimate the number of patients [with] Parkinson’s disease. The study also points out that age is the most important risk factor for Parkinson’s. As our population is aging, it is likely that we will see an uptick of PD cases.”

Recent research shows that dementia rates have declined by 13% each decade over the last 25 years.

When asked why Parkinson’s might be increasing as Alzheimer’s and other forms of dementia seem to be decreasing, Matt Farrer, Ph.D., neurologist and Lauren and Lee Fixel Chair and Professor of Neurology at the University of Florida, not involved in the study, explained to MNT:

“Dementia’s decline in incidence — adjusted for life expectancy and population size which are increasing — can be ascribed to changes in lifestyle and education (Mediterranean diet and exercise) and more widespread use of blood pressure, cholesterol, and anti-inflammatory medications in elderly populations .”

Dr. Farrer added that it’s difficult to say why PD is becoming more common. While a general rise in the condition correlates with industrialization; he noted that it’s tricky to try to “pin down” specific causes.

Dr. Paulina Gonzalez-Latapi, MSc, instructor of neurology at Northwestern University, not involved in the study, said MNT that environment plays an important role in most cases of PD. Pesticide and heavy metal exposure may contribute to the development of PD even decades before the onset of symptoms, Dr. Gonzalez-Latapi explained.

“Particularly interesting in this paper is the description of geographical areas within the US where PD is more common. We don’t have a good explanation for this at this point, but [these findings] certainly warrant more research on environmental exposures and other factors that may be more common in these areas. We also know that certain genetic changes can increase the risk of PD, so it may be that people in these places have a higher percentage of these genetic changes, although this has not been studied.”

MNT also spoke with Paramita Chakrabarty, Ph.D., associate professor at the Department of Neuroscience at the University of Florida.

Dr. Chakrabarty was not involved in the study but explained that improvements in diagnosis, such as differentiating between PD and Alzheimer’s and recognizing non-motor symptoms of PD, such as sleep-wake dysregulation, may also explain the increase in PD cases.

When asked about the limitations of the study, Dr. Natalie Diaz, a board-certified neurologist at the Pacific Movements Disorder Center at Pacific Neuroscience Institute at Providence Little Company of Mary Medical Center Torrance in Torrance, CA, not involved in the study, told MNT:

“While the study looks at PD incidence by age, sex, and geographical variation in each of the datasets, there is no mention of racial and ethnic differences. Caucasian and Hispanic populations have a higher incidence of PD as compared to African, American Indian, or Asian populations. Could race and ethnicity play a role in regional differences of incidence or could the changing demographics of our nation play a role in the increase of the projected incidence of PD in North America?”

Dr. Shilpa Chitnis, Ph.D., professor of neurology at UT Southwestern Medical Center, not involved in the study, added that the data may be unrepresentative of today, given the increased prevalence of risk factors such as diabetes, pesticides, and physical inactivity since 2012.

When asked how one may prevent Parkinson’s, Dr. Chakrabarty explained that none of the interventions used clinically to treat PD may protect from or reverse the neurodegeneration associated with the condition.

“Pharmacologics and deep brain stimulation bring about considerable symptomatic benefit to the patients, and somewhat extend their lifespan,” Dr. Chakrabarty added.

Dr. Gonzalez-Katapi added that certain factors, such as exercise, are associated with a lower risk of developing PD, even for those who may have a genetic risk for the disease.

“We have very clear data that exercise is beneficial for PD, and some data exploring it as a disease-modifying intervention,” she said.

“Following a healthy lifestyle, [such as] a diet higher in antioxidants, seems to be helpful. There is [also] some data to suggest that a lower dairy intake may also be protective, although this needs to be studied further.”

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