Continuous At-Home Monitoring of Nighttime Bed Behavior in Frontotemporal Dementia

Sleep and circadian disturbances are common yet understudied in frontotemporal dementia (FTD). Advances in non-invasive digital monitoring technology enable capture of real-time objective nighttime behaviors in naturalistic settings. We examined feasibility and utility of an unobtrusive, under-the-mattress sensor to monitor long-term bed behaviors in a sample of adults with FTD and their study partners.

This longitudinal observational study continuously monitored bed behaviors in participants with FTD recruited from the ALLFTD study for up to two years using an Emfit^™ Movement Monitor. Metrics were derived from each session in bed: duration in bed, time of bed-entry/exit, number of tosses/turns, and number of bed-exits. Bivariate relationships between baseline bed behaviors (aggregated across the first 30 days) and clinical characteristics (FTD vs. control; clinical dementia rating) were tested. Linear mixed-effects regressions examined longitudinal associations between baseline clinical severity and bed behaviors over time. To examine differential seasonal shifts in nightly bed behaviors, Fourier basis functions modeled nightly duration in bed over a full calendar year separately by clinical severity groups (controls vs. mild FTD vs. moderate-to-severe FTD).

Participants were 16 adults with FTD (mean age = 67; 69% male) and 12 study partner comparators (mean age = 62; 33% male). At baseline, participants with FTD had higher average durations in bed (mean difference=1.8, 95%CI [0.03, 3.61], p=0.046), more variability in durations in bed across days (mean difference=1.8, 95%CI [0.14, 3.37], p=0.035), and more bed exits than study partners (log-transformed; mean difference=0.5, 95%CI [0.02, 1.06], p=0.042). Longitudinally, person-specific linear trajectories of bed behaviors revealed that higher baseline clinical severity associated with significantly steeper increases in tosses/turns over time (β=0.15, 95%CI [0.05, 0.25], p=0.009). Those with more severe FTD also had an attenuated sleep-behavioral response to seasonal daylight shifts (β=0.23, 95%CI [0.13, 0.33], p<0.001).

Findings demonstrate the feasibility of long-term, non-invasive nighttime behavior monitoring using bed sensors, highlighting their utility to monitor disease progression in FTD with potential to detect person-specific changes and assess treatment effects. Further research is needed to explore underlying mechanisms of sleep disturbances in FTD and develop targeted interventions to improve sleep and subsequent quality of life for individuals with FTD.