Effects of substituting TV-watching time with physical activities or sleep on incident major depression. Results from the lifelines cohort study

Background. Physical activity is a known protective factor against depression but physical activity competes with other time-consuming behaviors that may increase depression risk. This study investigates the association between time spent in various movement-related activities and incident major depression, with a particular focus on the effects of replacing TV-watching time with other activities. Additionally, we explored whether the impact of substituting TV-watching differs across age groups. Methods. A population-based cohort study (Lifelines) with four-year follow-up, including 65,454 non-depressed adults (18+). Participants self-reported time spent in active commuting, leisure, sports, household, work or school physical-related activities, TV-watching, and sleep. Major depressive disorder was assessed using the Mini International Neuropsychiatric Interview. Compositional isotemporal data analysis was performed to analyze the effect of reallocating time in TV-watching with other activities adjusting for potential confounders. Interactions with age groups were also examined. Results. The incidence of major depressive disorder was 2.4%. Reallocating TV-watching time to any other physical activity or sleep reduced this risk in middle-aged adults. In older adults, only substituting TV-watching time with sports reduced the probability of becoming depressed. No significant reduction in probabilities for incident depression was 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 seems beneficial for older adults. Future research should aim to identify other activities, particularly in younger adults, that may prevent depression.