Accelerometer-derived movement behaviours and risk of mortality among individuals with pre-existing depression: prospective cohort study

Background Evidence is largely limited regarding the extent to which abnormal behavioural profiles, including physical inactivity, sedentary behaviour and inadequate sleep duration, impact long-term health conditions in individuals with pre-existing depression. Aims To investigate the associations between accelerometer-derived daily movement behaviours and mortality in individuals with pre-existing depression. Method Between 2013 and 2015, a total of 10 914 individuals with pre-existing depression were identified from the UK Biobank through multiple sources including self-reported symptoms, records of antidepressant usage and diagnostic recording based on the 10th Revision of the International Classification of Diseases (ICD-10) codes F32–F33. These participants were subsequently followed up until 2021. Wrist-worn accelerometers were used for objective measurement of sleep duration, sedentary behaviour, moderate-to-vigorous physical activity (MVPA) and light physical activity (LPA) over a span of seven consecutive days. Results During a median follow-up of 6.9 years, 434 deaths occurred among individuals with pre-existing depression. We observed a U-shaped association between sleep duration and mortality in individuals with pre-existing depression, with the lowest risk occurring at approximately 9 h/day. Both MVPA and LPA exhibited an L-shaped pattern in relation to mortality, indicating that engaging in higher levels of physical activity was associated with lower risk of mortality in individuals with pre-existing depression, but the beneficial effect reached a plateau after 50 min/day for MVPA and 350 min/day for LPA. We found a positive association between sedentary time and mortality, and the risk apparently increased above 8 h/day. Moreover, substituting 1 hour/day of sedentary time with LPA or MVPA was significantly associated with a 12% (hazard ratio: 0.88, 95% CI: 0.83–0.94) and 24% (hazard ratio: 0.76, 95% CI: 0.61–0.94) lower risk of mortality, respectively. Conclusions Our study found the beneficial effect of adequate sleep duration, high levels of physical activity and short sedentary time on risk of mortality among individuals with pre-existing depression.