A Behavioral Digital Intervention For Parkinson's Disease

Change in Physical Activity Levels

Physical activity will be measured using the International Physical Activity Questionnaire (IPAQ) - Short Form, a 7-item self-report instrument assessing time spent walking, in moderate-intensity activity, and in vigorous-intensity activity over the preceding week. Total physical activity will be calculated as MET-minutes per week using standard IPAQ scoring protocols: walking MET-min/week = walking minutes × walking days × 3.3 METs; moderate-intensity MET-min/week = moderate minutes × moderate days × 4.0 METs; vigorous-intensity MET-min/week = vigorous minutes × vigorous days × 8.0 METs. These are summed to yield total MET-min/week. Minutes per week of moderate-to-vigorous physical activity (MVPA) will also be calculated separately, and the proportion of participants meeting international physical activity recommendations (≥150 minutes of MVPA per week or ≥600 MET-min/week) will be reported.

Change in Fear of Falling

Assessed using the Falls Efficacy Scale International (FES-I), a 16-item self-report questionnaire assessing fear of falling during indoor and outdoor activities. Items are rated 1-4 (not at all concerned to very concerned), with total scores ranging 16-64. Higher scores indicate greater fear of falling. The FES-I shows excellent internal consistency (α = 0.96-0.98) and test-retest reliability (ICC = 0.91-0.94) in Parkinson's disease.

Change in Freezing of Gait Severity

Assessed using the New Freezing of Gait Questionnaire (NFOG-Q), a 9-item self-report instrument assessing freezing episodes, frequency, duration, and impact on daily life. Items are scored on a 0-4 scale; higher scores indicate greater freezing severity. Participants view a video demonstration of freezing episodes before completing the questionnaire to ensure accurate perception. The NFOG-Q demonstrates excellent internal consistency (α = 0.91) and validity in Parkinson's disease (ICC = 0.88).

Change in Quality of Life

Assessed using the Parkinson's Disease Questionnaire-8 (PDQ-8), the short form of the PDQ-39. This 8-item instrument assesses quality of life across eight domains: mobility, activities of daily living, emotional well-being, stigma, social support, cognition, communication, and bodily discomfort (one item per domain). Items are rated 0-4 (never to always) and transformed to a 0-100 scale, with higher scores indicating worse quality of life. The PDQ-8 demonstrates acceptable test-retest reliability (ICC = 0.76-0.93) and internal consistency (α = 0.72-0.95), and is strongly correlated with the full PDQ-39 (r = 0.94-0.97).

Change in Exercise Self-Efficacy

Assessed using the Exercise Self-Efficacy Scale (ESES), a 10-item self-report instrument measuring confidence in maintaining exercise despite barriers (e.g., fatigue, pain, time constraints). Items are rated on a 4-point scale (1 = Not always true to 4 = Always true). Total scores range from 10-40, with higher scores indicating greater self-efficacy for exercise. The ESES demonstrates moderate test-retest reliability in Parkinson's disease (ICC = 0.66).

Program Acceptability and Satisfaction

Assessed using the MOVE ON UP Participant Satisfaction Questionnaire, a 6-item measure rated on 5-point Likert scales (1 = Strongly Disagree to 5 = Strongly Agree) assessing: (1) ease of understanding; (2) ease of operationalizing instructions; (3) content appropriateness for people with Parkinson's; (4) content relevance to daily life; (5) program length (8 weeks, 3 sessions/week); and (6) likelihood of recommending the program to a friend with Parkinson's. Total scores range from 6 to 30, with higher scores indicating greater program satisfaction and acceptability. Open-ended questions will elicit qualitative feedback on barriers, facilitators, and suggestions for improvement.

Barriers and Facilitators to Physical Activity

Assessed at baseline using a tailored questionnaire developed based on a literature review of common barriers and facilitators to physical activity in people with Parkinson's disease. The questionnaire consists of 32 items asking participants to rate the extent to which each barrier affects their ability to engage in physical activity. Items are rated on a 5-point Likert scale (1 = Strongly disagree to 5 = Strongly agree). Individual items are analyzed descriptively; no total score is calculated. Responses will inform personalization of COM-B-based message prompts and allow for subgroup analyses of intervention response based on baseline barrier profiles.