by Dr. Jonathan Brotchie and Patrick Howson

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Parkinson’s disease is now the world’s fastest growing neurological disorder. In 2017, the Global Burden of Disease study found that between 1990 and 2016, age-standardized prevalence of Parkinson’s increased worldwide by nearly 22%. A paper from the following year even makes a case for “The Emerging Evidence of the Parkinson Pandemic”.

Parkinson Canada recently issued what should be an eye opening report for anyone with a stake in public health. “The Economic Burden of Parkinson’s in Canada” underscores the enormous impact the disease will have on patients, their families, and society in the years ahead, as that impact grows in proportion with the increasing prevalence.

It’s important to note as we consider this increase that the difference between trends in prevalence (the overall number of cases) and incidence (the number of new cases) can be difficult to distinguish, partly due to changes in case definition over time, but the net result according to this report’s estimates is that the economic burden of Parkinson’s for Canadians will rise from $3.3 billion in 2024 to $4.4 billion by 2034. And that’s only the direct costs, as the study “excludes costs related to diagnosis, long-term care or palliative care, costs for publicly insured drugs other than dopa and dopa derivatives,” along with many other factors, such as associated losses in work productivity, and “the monetization of decreased quality of life and mortality.” These are financially significant exclusions. In the US, we see the same trends: the annual burden of treatment is expected to rise from $52 billion this year to surpass $79 billion in 2037.

While mulling over the data, we wondered if there might actually be a counterintuitive good news story hiding within. Previously, diagnosing Parkinson’s might have taken up to ten years from the first visit to the doctor. Now, it’s often less than three. As well as diagnosing earlier, are we also not improving the treatment and care of people with the disease, and ultimately extending their life expectancy? Aging populations overall might seem the likeliest cause of the disease’s increased prevalence, but that alone would not necessarily explain why rates of Parkinson’s are growing faster than Alzheimer’s and other neurodegenerative diseases associated with aging. Though, it’s also important to note that since Parkinson’s symptoms tend to manifest later in life than many of those other diseases, often past 70, the percentage of people reaching this age does increase over time.

These aren’t really new questions. A 2018 editorial by Lawrence Golbe and Cristian Leyton in Neurology tracks the historical trajectory of Parkinson’s longevity, beginning just prior to the introduction of L-DOPA in 1967 when PD life expectancy was 9.4 years from onset to death, as reported by Hoehn and Yahr (“Parkinsonism: onset, progression and mortality”, Neurology).

By 1993, post levodopa but pre-deep brain stimulation (DBS), life expectancy had improved to 13.1 years (Hughes, Daniel, Blankson, Lees, “A clinicopathologic study of 100 cases of Parkinson’s disease”, Archives of Neurology). Jump ahead to 2016, and a new era of dopaminergic and antidyskinetic therapies, as well as deep brain stimulation, and it had increased further, to 14.6 (±7.7) years (De Pablo-Fernandez, Tur, Revesz, Lees, Holton, Warner TT, “Association of autonomic dysfunction with disease progression and survival in Parkinson disease”, JAMA Neurol).

DBS specifically has been measurably impactful. In 2023, according to Nils Schnalke et al, in Movement Disorders Clinical Practice, “Morbidity Milestones Demonstrate Long Disability-Free Survival in Parkinson’s Disease Patients with Deep Brain Stimulation of the Subthalamic Nucleus”, life expectancy was now estimated at 18 years. Likewise, in “Long-term outcomes following deep brain stimulation for Parkinson’s disease” (2019) published in the Journal of Neurosurgery, DBS provides durable relief of motor symptoms and improves life expectancy, contributing to a 10-year survival rate of 51% with Parkinson’s patients.

Of course, there are other explanations for this apparent increase in life expectancy; these studies are not truly comparing like with like. Many other factors, uncontrolled between them, could also be contributing. But can the trend toward people living longer with diagnosed Parkinson’s disease continue? We hope so, especially as new treatments continue to become available, at an even faster rate than we’ve seen over the last three to four decades. Indeed, just a few weeks ago we learned of FDA approval of Vyalev, a new L-DOPA based therapy from AbbVie.

What’s our take away from all this? First, we suggest that investments in research in recent decades have not only driven a deeper understanding of the biology of Parkinson’s symptoms, but have led to the development of better therapeutics that meaningfully impact people’s lives. Which is obviously great news.

But this only underscores the fact that we still do not have a disease modifying treatment for PD. The success of biological discovery at providing better symptomatic benefit, and increased life expectancy, should encourage us to double down on our commitment to do the same for the underlying disease process. With the recent passing of the National Plan to End Parkinson’s Act in the US, and the momentum now building around a biological definition of PD, it’s beginning to feel like we’ve entered an era where that’s finally achievable.