Patient Perception of Function Linked to Objective Severity of Parkinson Disease

Doctor talking to patient in office
The perception of motor and non-motor function of patients with Parkinson disease (PD) is associated with objective PD motor severity.

NICE, FRANCE — The perception of motor and non-motor function of patients with Parkinson disease (PD) is associated with objective PD motor severity, according to study results presented at the International Congress of Parkinson’s Disease and Movement Disorder, held September 22 to 26, 2019 in Nice, France.

As patient perception of illness receives more focus in medicine at large, the goal of the current study was to develop optimal models for a patient’s perception of motor and nonmotor function on objectively measures of severity in PD.

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The researchers used data from the Movement Disorder Society-Sponsored Revision of the Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) translation database, including complete examinations of 6684 patients. Patients reported functional impairment in nonmotor and motor domains that were used to model overall severity of PD as measured by the clinical examination from the MDS-UPDRS.

Automatic Linear Modeling using an All Possible Subset Best Model algorithm was used based on minimization of the Akaike Information Criterion. The resultant optimal model was replicated using the Overfit Prevention Criterion.

Several items in the nonmotor model were of significant importance, including urinary function, cognitive impairment, constipation, hallucinations and psychosis, fatigue, apathy, depression, daytime sleepiness, pain, and light headedness. Counterpart items of the model for motor functional impairment included tremor, walking and balance, getting out of bed, hygiene, handwriting, turning in bed, speech, eating, saliva and drooling, freezing of gait, dressing, chewing and swallowing, and hobbies.

Though these models for nonmotor, and motor functional impairment both demonstrated statistical significance in assessing objective PD severity (P <.0005 for both), AIC results demonstrated patients’ perceptions of motor function was superior to that of nonmotor function. However, the Overfit Prevention Criterion showed successful replication of both models

“These results demonstrate the linking of self-reported non-motor and motor function to objectively determined PD motor severity,” concluded the researchers.

“This is an important piece of research coming from a world renowned group and objectively defines what is now considered the benchmark concept of Parkinson’s disease, that it is effectively as much a non-motor disorder as it is motor, the latter being the traditionally defined concept of this fastest growing neurodegenerative disorder in the world,” commented K. Ray Chaudhuri, Professor of Movement Disorders and Clinical Director of the National Parkinson Foundation Centre of Excellence at Kings College in London. He goes on to note, “This research supports the importance and validity of combining motor and non-motor measurements of PD in terms of grading disease severity as can be done using the MDS-UPDRS.”


  1. C. Goetz, S. Luo, G. Stebbins. Modeling the effect of patient’s perception of non-motor and motor function on Parkinson’s disease severity. Poster presentation at the International Congress of Parkinson’s Disease and Movement Disorders; 22-26, 2019; Nice, France. Abstract: 1173.
  2. Patient’s Perception of Non-Motor and Motor Function Successfully Models Parkinson’s Disease Severity [news release]. Nice, France: Movement Disorder Society; September 24, 2019. Accessed September 25, 2019.