Is it Time for Changes to the MDS-UPDRS? Some Think So

The MDS-UPDRS, What is It?

The Movement Disorder Society’s Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) is a four-part assessment tool that evaluates the severity of a patient’s Parkinson’s disease based on how these tests are scored, with feedback from the patient and separate feedback from the neurologist, based on a zero to four scale for each question.  The scale is divided into four sections. Part I: Non-Motor Experiences of Daily Living: focuses on non-motor symptoms over the past week, including sleep quality, mood (depression, anxiety, apathy), and physical issues such as pain, constipation, or urinary problems. Part II, Motor Experiences of Daily Living, is fully patient-reported and asks about everyday functions such as speech, mobility, and walking.  Parts III and IV, which include the motor examination and motor complications, are scored by the attending physician and include questions based on a physical examination of their motor skills, and address any complications, guide medication usage, or make changes.

How the UPDRS Came About

The original UPDRS was formally introduced in 1987 as part of the Unified Parkinson’s Disease Rating Scale and became the dominant clinical and research scale globally during the late 80’s and early 90’s. Changes were called for because the current scale lacked standardization, and non-motor symptoms were underrepresented. Patient-reported symptoms, inconsistent ratings, and how they were handled by the neurologists often led to confusion in test results. To address these gaps, the International Movement Disorder Society released a revised version of the scale in 2008, known as the MDS-UPDRS, which underwent revisions to address the open gaps left by the original UPDRS that focused on which items were patient-reported versus doctor-rated and expanded non-motor symptom coverage, and standardized scoring instructions

Proposed Changes

So in 2026, a new group of researchers challenged the long-standing assumption that the MDS-UPDRS scale doesn’t follow Parkinson’s disease progression well enough based on the length of the disease over time in a patient. In their article, “Optimizing Parkinson’s disease progression scales using computational methods,” a group challenged the current methodology in place. 

They argue that the MDS-UPDRS adds up a lot of symptoms and assumes they all matter the same, but the data says it isn’t true. Researchers state that “Clinical scales like the MDS-UPDRS rely on summing item values, assuming uniform item importance and score increments,” an assumption the authors show is not supported by longitudinal patient data. 

If you break that quote down, it means the MDS-UPDRS adds up symptoms as if they all matter the same and worsen in equal steps, but real patient data shows that isn’t how Parkinson’s actually progresses. The scale treats all symptoms and score changes as equal, but real patients don’t change that way over time. Even if symptoms go up and down day to day, the disease itself doesn’t reverse. 

“We do not wish to replace the MDS-UPDRS. It is a highly valuable source of information. What we propose is to summarize it differently, in a way that reflects better the tendency of the disease to progress over time. The study, conducted by my graduate student Assaf Benesh, shows that by using mathematical optimization, one can reweight questions and increments, obtaining a more monotone – and possibly simpler – scale summary,  using far fewer items and increments. The study was done in collaboration with Prof. Nir Giladi, who sadly passed away recently, Prof. Anat Mirelman, and Prof. Roy Alcalay, from Tel Aviv Sourasky Medical Center. We hope our work will raise interest in new ways of analyzing the MDS-UPDRS, to enable novel and improved ways of tracking and eventually treating Parkinson’s Disease.”

Professor Ron Shamir, Blavatnik School of Computer Science and AI

According to patient data, while patient scores over time decrease between visits, these changes could be the result of medication changes, symptoms of the disease tend to go up and down day to day, and some of the current questions in the MDS-UPDRS aren’t sufficient to track disease progression. So the scores didn’t track how the disease is actually getting worse over time.  “For instance, a score of 2 on two different items could have markedly different clinical implications, yet both add the same amount to the total score.” 

If you follow the structure and think of how the questions are laid out in their paper,  then MDS-UPDRS should work as intended. Throwing out questions should make the conditions someone has worse, not better, and more questions should mean a better measure of disease progression. The researchers point out that “The total score is obtained by summing item scores, assuming that all items, and all increments within items, are equally informative,” and “although thoroughly validated and widely accepted, the MDS-UPDRS assumes that all items, and all score increments, contribute equally to disease severity.”

It is suggested that questions that contribute little to no Parkinson’s progression should be removed so doctors can focus on the symptoms that matter most without losing accuracy. Their findings also suggest that patient-reported questions tend to be more informative over time, and should be considered more to reflect how the disease is progressing. “Overall, the optimized index could enhance the quality and efficiency of patient care and improve long-term disease management. For transparency and continuity, we recommend reporting both the traditional MDS-UPDRS total score and the optimized index side-by-side whenever feasible.” 

By doing so, this can give neurologists and other clinicians additional information and options to improve decisions and treatments about patient care whenever possible. 

Counterargument

While the authors present strong evidence that reweighting MDS-UPDRS items improves measurement of disease progression, several important counterarguments remain. 

Parkinson’s disease doesn’t treat everyone equally, for everyone. Symptoms can change from one day to the next, and the response to medications can also differ as well. Symptoms can be influenced by mood, fatigue, or their perception of how they are feeling on a particular day, and symptoms like tremor may not track how someone’s symptoms are progressing, but still influence a patient’s daily life. These changes are how doctors can help see potential problems for patients down the road. 

It is worth noting that some of the data in the study mainly looked at people in the early stages of Parkinson’s; the results may not apply to those with more advanced disease. While using fewer questions may improve accuracy on paper, doctors use these scales for many purposes beyond tracking progression, not just for research.

Their Conclusions

Taken together, the findings do not suggest that the MDS-UPDRS is obsolete or invalid, but rather that the way its total score is constructed no longer matches what patient data reveals about Parkinson’s disease progression. Instead, they point to a limitation in how its total score is added up and doesn’t always reflect how Parkinson’s in the body actually progresses over time, but the researchers feel that, if treating all of the symptoms and scores as equal, the current scale can hide what real changes are happening and not giving accurate enough results.

This study shows that letting real patient data decide which symptoms matter most leads to a clearer and more useful way to track symptom progression. As Parkinson’s research is focusing more on earlier diagnosis, remote monitoring, disease-modifying, and whole body treatments, getting the most accurate diagnosis may be just as important as treating the disease itself.