Background: Physical activity is a protective factor for depression, but its interrelation in time with other movement activities like sedentary behavior and sleep is often ignored. This study examines the association between time spent in different movement activities and incident depression, and the impact of replacing TV-watching time with other activities.
Methods: A population-based cohort study (Lifelines) with four-year follow-up including 76,164 non-depressed adults. Participants self-reported time spent in active commuting, leisure, sports, household, work or school activities, TV-watching (proxy of sedentary behavior), and sleep. Depressive disorder was assessed using the Mini International Neuropsychiatric Interview. Multivariable logistic regression analyses, followed by isotemporal substitution analyses adjusted for potential confounders, were performed to analyze the effect of reallocating 30 minutes of TV-watching time with other activities. Analyses were stratified by age, i.e. younger (18-39y), middle-aged (40-59y) and older adults (≥60y).
Results: The incidence of major depressive disorder was 2.4%. TV-watching time increased the risk of depressive disorder in middle-aged adults, and its substitution with any other physical activity or more sleep reduced this risk. In older adults, only the substitution of TV-watching time with sports reduced the odds of becoming depressed. No significant associations were found in younger adults.
Conclusion: Replacing TV-watching time with other activities, including sleep, may serve as a preventive strategy against depressive disorder in middle-aged adults, while only the substitution with sports was beneficial for older adults. Future research should aim to identify other activities, particularly in younger adults, that may prevent depression.
Keywords: depression, physical activity, sedentary behavior, sleep, isotemporal substitution analysis.