BACKGROUND:
Digital health technologies (DHTs) offer promising tools for remote symptom monitoring, contributing to the early detection of frontotemporal dementia (FTD). The Genetic FTD Initiative (GENFI) has implemented DHTs to enhance detection and develop outcome measures for clinical trials. One approach is the use of wearables to monitor heart rate variability (HRV), which reflects changes in parasympathetic nervous system function.
METHODS:
Participants attended their GENFI research visit at UCL and completed the CDR+NACC-FTLD during their clinical examination. After the visit, a Fitbit was provided for at home use. Resting HRV was measured through average root mean square of successive differences (RMSSD) per person over 28-days. Mutation carriers were classified based on CDR+NACC-FTLD stages: asymptomatic (0; n = 18, mean age = 34.8, SD = 8.5), prodromal (0.5; n = 40, mean age = 44.2, SD = 10.7), and symptomatic (≥1; n = 7, mean age = 62.9, SD = 5.7). Differences in average RMSSD between these groups and 27 mutation-negative controls (mean age = 46.2, SD = 13.0) were analysed using a linear regression model, adjusting for age.
RESULTS:
Asymptomatic mutation carriers had greater HRV with significantly higher RMSSD scores (mean=49.2, SD=23.7), compared to mutation negative controls (mean=30.6, SD=9.80, p<0.01). No significant differences were found between controls and prodromal mutation carriers (mean=32.8, SD=12.7, p=0.93) or between controls and symptomatic mutation carriers (mean=20.5, SD=2.60, p=0.36), although there was a trend to a lower RMSSD in the latter group.
CONCLUSION:
Significant differences in HRV were observed at the asymptomatic stage, with carriers showing increased HRV compared to controls. This variability may reflect heightened physiological stress in response to early neurodegenerative changes. However, HRV declined at later disease stages, suggesting progressive parasympathetic dysfunction. This is the first study exploring stage-specific HRV changes in FTD, highlighting the potential of DHTs as early biomarkers.