Background: Smartphones may significantly contribute to the detection of early cognitive decline at scale by enabling remote, frequent, sensitive, economic assessment. Several prior studies have sustained engagement with participants remotely over a period of a week; extending this to a period of a month would clearly give greater opportunity for measurement. However, as such study durations are increased, so too is the need to understand how participant burden and scientific value might be optimally balanced. Objectives: We explore the 'little but often' approach to assessment employed by the Mezurio app, interacting with participants every day for over a month. We aim to understand whether this extended remote study duration is feasible, and which factors might promote sustained participant engagement over such study durations. Methods: Thirty-five adults (aged 40-59 years) with no diagnosis of cognitive impairment were prompted to interact with the Mezurio smartphone app platform for up to 36 days, completing short, daily episodic memory tasks in addition to optional executive function and language tests. A subset (n=20) completed semi-structured interviews focused on their experience using the app. Results: Average compliance with the schedule of learning for subsequent memory test was 80%, with 88% of participants still actively engaged by the final task. Thematic analysis of participants' experiences highlighted schedule flexibility, a clear user-interface, and performance feedback as important considerations for engagement with remote digital assessment. Conclusions: Despite the extended study duration, participants demonstrated high compliance with the tasks scheduled and were extremely positive about their experiences. Long durations of remote digital interaction are therefore definitely feasible, but only when careful attention is paid to the design of the user experience.
JMIR mHealth and uHealth