Caveats, Cautionary Notes
Adopting a biological definition of PD would represent a shift as the field has prompted considerable discussion and healthy debate.
Commenting for this news organization, James Beck, PhD, chief scientific officer at the Parkinson’s Foundation, said the principle behind the proposed classifications is where “the field needs to go.”
“Right now, people with Parkinson’s take too long to get a confirmed diagnosis of their disease, and despite best efforts, clinicians can get it wrong, not diagnosing people or maybe misdiagnosing people,” Dr. Beck said. “Moving to a biological basis, where we have better certainty, is going to be really important.”
Beck noted that the NSD-ISS “goes all in on alpha-synuclein,” which does play a big role in PD, but added, “I don’t know if I want to declare a winner after the first heat. There are other biomarkers that are coming to fruition but still need validation, and alpha-synuclein may be just one of many to help determine whether someone has Parkinson’s disease or not.”
Un Kang, MD, director of translational research at the Fresco Institute for Parkinson’s & Movement Disorders at NYU Langone Health, New York City, told this news organization that alpha-synuclein has “very high diagnostic accuracy” but cautioned that the adoption of a biological definition for PD would not usurp a clinical diagnosis.
“We need both,” Dr. Kang said. “But knowing the underlying pathology is important for earlier diagnosis and testing of potential therapies to treat the molecular pathology. If a patient doesn’t have abnormal synuclein, you may be treating the wrong disease.”
The coauthors of recent JAMA Neurology perspective said the biological definitions are “exciting, but there is “wisdom” in tapping the brakes when attempting to establish a biological definition and classification system for PD.
“Although these two proposals represent significant steps forward, a sprint toward the finish line may not be wise,” wrote Njideka U. Okubadejo, MD, with University of Lagos, Nigeria; Joseph Jankovic, MD, with Baylor College of Medicine, Houston; and Michael S. Okun, MD, with University of Florida Health, Gainesville, Florida.
“A process that embraces inclusivity and weaves in evolving technological advancements will be important. Who benefits if implementation of a biologically based staging system for PD is hurried?” they continued.
The proposals rely heavily on alpha-synuclein assays, they noted, which currently require subjective interpretation and lack extensive validation. They also worry that the need for expensive and, in some regions, unattainable biological fluids (CSF) or imaging studies (dopamine transporter scan) may limit global access to both PD trials and future therapeutics.
They also worry about retiring the name Parkinson’s disease.
“Beyond the historical importance of the term Parkinson disease, any classification that proposes abandoning the two words in either clinical or research descriptions could have unintended global repercussions,” Dr. Okubadejo, Dr. Jankovic, and Dr. Okun cautioned.
Dr. Beck told this news organization he’s spoken to clinicians at meetings about this and “no one really likes the idea” of retiring the term Parkinson’s disease.
Frederick Ketchum, MD, and Nathaniel Chin, MD, with University of Wisconsin–Madison, worry about the “lived” experience of the asymptomatic patient after receiving a biological diagnosis.
“Biological diagnosis might enable effective prognostication and treatment in the future but will substantially change the experience of illness for patients now as new frameworks are slowly adopted and knowledge is gained,” they said in a correspondence in The Lancet Neurology.
“Understanding and addressing this lived experience remains a core task for health professionals and must be made central as we begin an era in which neurological diseases are redefined on a biological basis,” Dr. Ketchum and Dr. Chin advised.
A complete list of agencies that supported this work and author disclosures are available with the original articles. Dr. Beck and Dr. Kang had no relevant disclosures.
A version of this article first appeared on Medscape.com.