Study Protocol and Characteristics of the Wearable Device Survey for Tohoku Medical Megabank Brain Magnetic Resonance Imaging Study.

Sleep and physical activity play a crucial role in brain and mental health. While traditional self-reported methods and research-grade accelerometers have several limitations, consumer-grade wearable devices, such as Fitbit, allow continuous, objective, and real-life data collection. The purpose of this article is to report the study protocol and participant characteristics of a wearable device survey that primarily aims to examine the relationship between brain health and long-term patterns of daily physical activity and sleep.Nearly 2,000 participants were recruited between September 2022 and December 2023, as part of the Tohoku Medical Megabank Brain Magnetic Resonance Imaging Study, to wear Fitbit Charge 5 devices for 1 year, continuously tracking physical activity and sleep. Additionally, home blood pressure measurements and questionnaire data on housing conditions, psychological distress, and medication were collected every 4 months for a total of four assessments.The mean age of the participants was 58.5 years and 37.4% were men. For the first 30 days after the recruitment, mean step count was 8,910 steps/day, and a mean total sleep time was 370.4 min/night (approximately 6.2 h). The mean morning systolic blood pressure and diastolic blood pressure were 126.2 and 75.5 mmHg, respectively.This study provides a unique opportunity to integrate longitudinal consumer-grade wearable data, brain MRI, multiomics data, and comprehensive health records from existing cohorts to advance precision medicine and help prevent mental and neurodegenerative diseases, such as dementia. Limitations include potential selection bias, and a relatively smaller sample size than larger global studies.