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Affiliation
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Department of Psychiatry, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Epidemiology, Harvard T H Chan School of Public Health, Boston, MA, USA; Psychiatric & Neurodevelopmental Genetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA; Stanley Center for Psychiatric Research, Broad Institute, Boston, MA, USA. |
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Abstract
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Adolescence is a key window of vulnerability for depression, the leading cause of disability worldwide. The prevention of depression among young people is therefore of substantial public health importance. A growing body of large-scale data now supports the conclusion that physical activity is associated with a reduced risk of depression1, 2 and thus serves as a promising prevention target. However, few studies have focused on adolescents and, of these, many are cross-sectional and have relied on self-report measures of physical activity that might poorly capture the full range of relevant activities over time.
In The Lancet Psychiatry, Kandola and colleagues3 draw on a prospective population-based cohort from which objective measures of physical activity were collected4 at three different timepoints (around 12 years, 14 years, and 16 years of age) to provide the most fine-grained characterisation to date of physical activity patterns across adolescence and their implications for depression. Between 12 years and 16 years of age, mean time spent in sedentary behaviour increased by more than 90 min/day—from about 7·2 h/day (SD 1·1) to 8·7 h/day (1·1). A 60 min/day increase in sedentary behaviour at any of the three timepoints was associated with an 8–11% higher depression score at 18 years of age. Notably, this risk appeared to be driven by the displacement of light physical activity: decreases in the amount of light activity directly mirrored increases in sedentary behaviour between 12 years and 16 years of age, and each 60 min/day increase in light activity was associated with a lower depression score at 18 years, with effects that were opposite and roughly equal in magnitude to those of sedentary behaviour. Findings persisted when adjusting for baseline depressive symptoms or when excluding individuals with elevated baseline symptoms, and even when considering depression as a binary outcome. Notably, moderate-to-vigorous physical activity, which has been the focus of most previous studies, had a less consistent association with depression compared with those of light activity or sedentary behaviour.
Adolescents are known to become less active over time,5 for multifactorial reasons. The good news from this study is the implication that light activity—which can include movements as simple as standing, stretching, or casual walking—might be an effective strategy for decreasing the burden of adolescent depression. While not able to establish causality, this study's fully prospective analyses and adjustment for a range of plausible confounders ...
Language: en |