Smartphone self-testing of hand and speech motor functions: a study of reliability and usability in older adults.

Scalable remote-monitoring tools of motor function are vital for early detection and tracking of neurodegenerative diseases. This study evaluated the reliability and usability of TapTalk, a 2-min validated smartphone-based self-assessment of hand and speech motor function, in older adults. Community-dwelling adults aged 50 + completed TapTalk daily for 7 days: once in the research center and six consecutive days at home. Motor features were extracted using validated algorithms. Test-retest reliability was analyzed using intraclass correlation coefficient (ICC) and usability via descriptive analysis of user-experience questionnaires. Four-hundred and twenty-five sessions of TapTalk were completed by 68 participants (68.6 ± 6.6 years; range 57-80; 75% female) across 43 smartphone models. All tests had features with ICC > 0.5 except for one, indicating acceptable reliability for a self-administered in-home test. Usability scores averaged 95.9% reflecting high satisfaction with ease-of-use, clarity, and performance. Findings support TapTalk's potential for scalable longitudinal monitoring. Establishing reliability and usability in older adults is a critical step toward TapTalk's broader use by those with neurodegenerative diseases.