Abstract
SummaryBackgroundIdentifying modifiable risk factors is essential to reduce the prevalence adolescent depression. Self-report data suggest that physical activity and sedentary behaviour might be associated with depressive symptoms in adolescents. We examined associations between depressive symptoms and objectively measured physical activity and sedentary behaviour in adolescents.MethodsFrom a population-based cohort of adolescents whose mothers were invited to participate in the Avon Longitudinal Study of Parents and Children (ALSPAC) study, we included participants with at least one accelerometer recording and a Clinical Interview Schedule-Revised (CIS-R) depression score at age 17·8 years (reported as age 18 years hereafter). Amounts of time spent in sedentary behaviour and physical activity (light or moderate-to-vigorous) were measured with accelerometers at around 12 years, 14 years, and 16 years of age. Total physical activity was also recorded as count per minute (CPM), with raw accelerometer counts averaged over 60 s epochs. Associations between the physical activity and sedentary behaviour variables and depression (CIS-R) scores at age 18 years were analysed with regression and group-based trajectory modelling.Findings4257 adolescents from the 14 901 enrolled in the ALSPAC study had a CIS-R depression score at age 18 years. Longitudinal analyses included 2486 participants at age 12 years, 1938 at age 14 years, and 1220 at age 16 years. Total follow-up time was 6 years. Total physical activity decreased between 12 years and 16 years of age, driven by decreasing durations of light activity (mean 325·66 min/day [SD 58·09] at 12 years; 244·94 min/day [55·08] at 16 years) and increasing sedentary behaviour (430·99 min/day [65·80]; 523·02 min/day [65·25]). Higher depression scores at 18 years were associated with a 60 min/day increase in sedentary behaviour at 12 years (incidence rate ratio [IRR] 1·111 [95% CI 1·051–1·176]), 14 years (1·080 [1·012–1·152]), and 16 years of age (1·107 [1·015–1·208]). Depression scores at 18 years were lower for every additional 60 min/day of light activity at 12 years (0·904 [0·850–0·961]), 14 years (0·922 [0·857–0·992]), and 16 years of age (0·889 [0·809–0·974]). Group-based trajectory modelling across 12–16 years of age identified three latent subgroups of sedentary behaviour and activity levels. Depression scores were higher in those with persistently high (IRR 1·282 [95% CI 1·061–1·548]) and persistently average (1·249 [1·078–1·446]) sedentary behaviour compared with those with persistently low sedentary behaviour, and were lower in those with persistently high levels of light activity (0·804 [0·652–0·990]) compared with those with persistently low levels of light activity. Moderate-to-vigorous physical activity (per 15 min/day increase) at age 12 years (0·910 [0·857–0·966]) and total physical activity (per 100 CPM increase) at ages 12 years (0·941 [0·910–0·972]) and 14 years (0·965 [0·932–0·999]), were negatively associated with depressive symptoms.InterpretationSedentary behaviour displaces light activity throughout adolescence, and is associated with a greater risk of depressive symptoms at 18 years of age. Increasing light activity and decreasing sedentary behaviour during adolescence could be an important target for public health interventions aimed at reducing the prevalence of depression.FundingDetails of funding are provided in the Acknowledgments.
Highlights
Depression affects around 300 million people worldwide.[1]
Total physical activity decreased between 12 years and 16 years of age, driven by decreasing durations of light activity and increasing sedentary behaviour (430·99 min/day [65·80]; 523·02 min/day [65·25])
Higher depression scores at 18 years were associated with a 60 min/day increase in sedentary behaviour at 12 years, 14 years (1·080 [1·012–1·152]), and 16 years of age (1·107 [1·015–1·208])
Summary
Depression affects around 300 million people worldwide.[1]. Among adolescents, the prevalence of depression appears to be increasing, with one US-based study showing an increase from about 8·7% in 2005 to 11·3% in 2014.2 The first onset of depression tends to be during adolescence, which represents an important window for identifying modifiable risk factors and intervening to prevent depression in later life.[3,4] Increasing evidence suggests that physical activity can reduce the symptoms of depression in clinical and non-clinical populations. Evidence before this study Identifying modifiable risk factors for adolescent depression is a global priority. Low physical activity and high sedentary behaviour could be important early risk factors for depression that are modifiable through practical population-level approaches with relatively few risks. We found some evidence from population-based studies that total or moderate-to-vigorous physical activity levels were negatively associated with the risk of depression. The single prospective study identified in our search that used objective physical activity measures in adolescents found no association between total or moderate-to-vigorous activity levels and depression. The study was limited by its small sample size, did not record sedentary behaviour or light activity, included only one measure of physical activity (at baseline), and was unable to examine the effect of activity changes over time during adolescence. Several studies have used objective measures to show that sedentary behaviour progressively displaces light activity throughout adolescence, but the implications of this activity shift—including the potential harms of sedentary behaviour and benefits of light activity—are unknown, and more high-quality evidence is needed
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