Objectively-measured sedentary behavior and physical activity with depression in older adults: an isotemporal substitution analysis

Abstract

The aim of this study was to use the Isotemporal Substitution (IS) model to examine the cross-sectional associations of accelerometer measurements of sedentary behavior (SB), low- intensity activity (LPA) and moderate- to vigorous- intensity physical activity (MVPA) with depression when replacing one activity for another in sample of older Japanese adults. The IS model was created to study the time-substitution effects of one activity replacing another. The participants were 305 older people (190 men and 115 women) aged from 65 to 85 years (mean 74.6±5.2 years). We used accelerometers (Active style Pro HJA-350IT, Omron Healthcare, Kyoto, Japan) to assess participant’ SB and PA, and calculated the daily average time spent on SB (≤1.5 METs), low- intensity PA (>1.5 to <3.0 METs) and moderate- to vigorous- intensity PA (≥3.0 METs) per day. Depression was assessed using the Japanese-language version of the 15 item Geriatric Depression Scale (GDS-15). The mean time of participant’ SB, LPA, MVPA were 521±119 min/day, 327±103 min/day and 50±34 min/day, respectively. The IS model showed that replacing 10-minute of SB with LPA was significantly associated with lower GDS-15 score after controlling for age, sex and body mass index. Our findings indicated that replacing SB with LPA leads to improvements depression in older Japanese adults. Those favorable effects were obtained with replacing of only 10 minutes per day.