Development of a Scale for Psychosis in Parkinson’s Disease: The Movement Disorders Society- Parkinson’s Disease Psychosis Rating Scale (MDS-PDPRS)
Michelle Tosin1, Tiago Mestre2, Glenn Stebbins1, Graziella Mangone3, Sandra Videmsky4, Shazia Ali4, Jennifer Goldman5, Tien Khoo6, Simon Lewis7, Pablo Martinez-Martin8, Oluwadamilola Ojo9, Javier Pagonabarraga10, Anette Schrag11, Daniel Weintraub12, Christopher Goetz1
1Rush University Medical Center, 2University of Ottawa, 3Institut du Cerveau et de la Moelle Epinière – Université Pierre et Marie Curie, 4International Parkinson and Movement Disorders Society, 5JPG Enterprises LLC, 6Griffith University, 7University of Sydney, 8Carlos III Institute of Health, 9University of Lagos, 10Hospital de la Santa Creu i Sant Pau, 11University College London, 12University of Pennsylvania
Objective:
Determine face and content validity of the MDS-PDPRS.
Background:
There is no validated clinical outcome assessment designed to measure the functional impact of Parkinson’s disease psychosis (PDP). The MDS-PDPRS is being developed as a clinician-reported outcome assessment to evaluate PDP severity and impact on daily functions and activities. It includes a five-item Diagnostic Screening Questionnaire to identify PDP, followed by a two-part inventory with 14 Likert-type questions for those meeting inclusion criteria: Part 1 – PDP Severity (six items) and Part 2 – Functional Impact (eight items).
Design/Methods:
Between August 2024 and September 2025, 43 native English-speaking participants from the United States, Nigeria, Australia, and Canada participated in three rounds of virtual cognitive interviewing. The goal was to assess scale clarity, relevance, meaningfulness, completeness and comfort of administration for interviewers, patients, and care partners. Respondents were divided into three groups:
1. Movement Disorder Specialists (n=11): Evaluated all interview sections and rated the entire MDS-PDPRS.
2. PDP Patients and Care Partners (n=16 each): Evaluated the Diagnostic Screening Questionnaire and all items through Part 2: PDP Functional Impact.
3. PD Patients and Care Partners (n=16 each): Evaluated only the Diagnostic Screening Questionnaire.
Patients and care partners were screened for cognition using the Montreal Cognitive Assessment (MoCA) Version 8.1 BLIND (Normal, ≥ 19/22).
Results:
MoCA scores ranged from 16 to 22 in PD patients, from 13 to 22 in PDP patients, and from 17 to 22 in care partners. The recommended refinements focus on clarifying medical terminology (severity), modifying transition instructions, and refining instructional wording. Key modifications include refining the symptom recall timeframe, adjusting response options for better accuracy, and reconsidering item relevance (item 7: Ability to Go Outside the Home).
Conclusions:
The MDS-PDPRS shows face and content validity for assessing PDP severity and its functional impacts. Clinimetric evaluation is planned as the next step of validation.
Disclaimer: Abstracts were not reviewed by Neurology® and do not reflect the views of Neurology® editors or staff.