Patients with unrecognized or prodromal Parkinson’s disease (PPD) experience problems with mobility, muscle weakness, and struggle with other aspects of daily functioning up to 3 years before diagnosis, new research shows.
The new findings come from a large case-control study that analyzed Medicare claims data to evaluate functional limitations in PPD, leading the investigators to suggest PPD should be recognized as a distinct disease stage.
Dr Cameron Miller-Patterson
“It’s increasingly recognized as a stage of Parkinson’s and there is an argument here for that,” lead investigator Cameron Miller-Patterson, MD, assistant professor of neurology at Virginia Commonwealth University in Richmond, told Medscape Medical News. “Because we’re finding that people with prodromal Parkinson’s may have functional limitations, identifying them sooner and getting them the appropriate symptomatic therapy could be helpful.”
The findings were published online December 19 in JAMA Neurology.
Improving Quality of Life
Individuals with PPD have symptoms of Parkinson’s, but not enough to meet diagnostic criteria. However, all PPD patients eventually meet that threshold.
To evaluate whether functional limitations are present in individuals with PD prior to diagnosis vs the general population, researchers analyzed Medicare-linked data on 6674 individuals aged 65 and older who participated in the National Health and Aging Trends Study (NHATS), a longitudinal survey in the United States. Survey questions evaluated dexterity, eating, mobility, mood, pain, sleep, speech, strength, and vision.
Patients with incident PD were defined as having two or more Medicare diagnoses. Controls were defined as those with Medicare eligibility at baseline and 2 or more years prior, with no diagnosis.
Compared with individuals who never had PD, those who eventually received a diagnosis were less likely to report being able to walk 6 blocks (odds ratio [OR], 0.34; 95% CI, 0.15 – 0.82), stand independently from kneeling (OR, 0.30; 95% CI, 0.11 – 0.85) or lift a heavy object overhead (OR, 0.36; 95% CI, 0.15 – 0.87). They were also more likely to report imbalance (OR, 2.77; 95% CI, 1.24 – 6.20) 3 years prior to diagnosis.
“Generally, we don’t start treating people until we see them in the clinic and give them a diagnosis of Parkinson’s,” Miller-Patterson said. “If we identify them earlier, even before diagnosis, we may be able to improve their quality of life by treating them sooner.”
Serving Patients Better
Better recognition of PPD could also help identify participants for clinical trials of therapeutics that could slow disease progression, something that is beyond the ability of currently approved medications.
This, and growing support for distinguishing PPD as an official stage of PD, makes findings such as these both timely and important, authors of an accompanying commentary write.
“The recognition of a prodromal period has been viewed as potentially critical to the success of disease-modifying interventions, on the argument that it may be too late to enact meaningful clinical change once symptoms clinically manifest given the degree of neurodegeneration already present,” Ian O. Bledsoe, MD, Weill Institute for Neurosciences, University of California, San Francisco, and co-authors write.
One limitation, however, is that the study design didn’t allow researchers to determine if individuals with eventual PD who reported parkinsonian symptoms had prodromal PD or undiagnosed disease. The answer would clarify whether prodromal PD is more common than previously thought or if PD diagnosis is often delayed for years — or both.
“Despite the limitations of this study, its broader point and importance remain: people appear to have some markers of functional decline before they are diagnosed with PD,” the editorialists write. “Additionally, motor dysfunction may arise at an earlier time point in the disease than we typically think. There is a potential opportunity to serve this population better.”
The study was funded by the National Institutes of Health. Miller-Patterson reported receiving other NIH grants during the course of the study. Bledsoe reported personal fees from Boston Scientific, Amneal Pharmaceuticals, IDEO, Accorda, Humancraft.com, and Putnam Associates, grants from the National Institutes of Health, the Michael J. Fox Foundation, and the Dystonia Medical. Full disclosures are available in the original articles.
JAMA Neuro. Published online December 19, 2022. Abstract, Editorial
Kelli Whitlock Burton is a reporter for Medscape Medical News covering neurology and psychiatry.
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