Abstract and Introduction
Mental health (MH) and behavioral health are fundamental to a good quality of life. Only a few studies have investigated the association between behavioral health (e.g., physical activity (PA), screen time (ST)) and MH from childhood to adolescence. Therefore, we investigated the relationships of PA and ST with MH by sex in an 11-year longitudinal cohort study of German schoolchildren during 2003–2017. A subsample (n = 686; 55.2% female) of participants from the German Motorik-Modul (MoMo) Longitudinal Study who participated in all 3 measurement phases (mean ages: time 1 (baseline; 2003–2006), 5.57 (standard deviation (SD), 1.00) years; time 2 (wave 1; 2009–2012), 11.85 (SD, 1.03) years; time 3 (wave 2; 2014–2017), 16.86 (SD, 1.04) years) were analyzed with regard to PA, ST, and MH (emotional symptoms, conduct problems, hyperactivity/inattention, peer relationship problems, prosocial behavior, and overall strengths and difficulties). Path panel prediction models were fitted with time 1, time 2, and time 3 PA, ST, and MH indicators. PA predicted less television (TV)/video watching in females, and TV/video watching predicted personal computer (PC)/Internet use in both sexes. Behavior and MH results suggested that, for females, higher TV/video watching and PC/Internet use was related to higher MH challenges over the course of maturation. Some preadolescent males' MH challenges increased ST (TV/video watching and PC/Internet use) in adolescence. Researchers should explore innovative and effective methods for reducing childhood ST, especially among females with early signs of MH issues, and addressing preadolescent males' MH challenges.
Mental health (MH), as a positive state of psychological well-being, is fundamental to a good quality of life, especially in childhood and adolescence but also in adults. Happy and confident children and adolescents are most likely to grow into happy and confident adults, who in turn contribute to the health and well-being of nations. However, MH problems affect 10%–20% of children and adolescents worldwide and account for a large portion of the global burden of disease.[2,5] In a nationwide survey in Germany, 14.5% of children and 18.5% of adolescents were shown to suffer from at least 1 specific self-reported MH problem or had an overall self-reported MH problem indicated by an abnormal score on the Strengths and Difficulties Questionnaire (SDQ).[6,7] In another study, Schmid et al. found a prevalence of mental disorders of 59.9% according to the International Classification of Diseases, Tenth Revision, diagnostic criteria. Most commonly, adolescents suffer from depression, anxiety, or attention-deficit/hyperactivity disorder.[9–11] In many settings, suicide is among the leading causes of death in young people.
Sedentary behavior negatively influences MH in adults, adolescents, and even children. Especially sedentary behavior operationalized as screen time (ST) in children and adolescents is an increasing problem worldwide, as well as in German children and adolescents. In a study by Bucksch et al., while television (TV) viewing time decreased over the 8-year study period, there was no overall decline in the observed duration of screen-based behaviors, which was mainly due to a marked increase in personal computer (PC) use. Increasing ST is critical because it gives rise to health-related concerns, which are well documented in German children and adolescents. Contrary to the negative influence of ST, physical activity (PA) is known to have a positive influence on MH, especially in children and adolescents,[16–18] which has also been documented in German children. Taken together, an increase in PA and/or a decrease in ST may positively influence MH in adolescents, especially as a protective factor during maturation. In a review of reviews on PA and MH in children and adolescents, Biddle and Asare found small-to-moderate effects of PA on MH outcomes, whereas in another review of reviews, de Rezende et al. found moderate negative associations between ST and MH outcomes. Furthermore, only a few studies have examined both factors at the same time. However, it is important to investigate both PA and ST concomitantly, as this allows for accounting for their interrelationship and for distinguishing the independent and interactive effects of PA and ST on MH outcomes. Longitudinal studies suggest that an increase in PA and a decrease in sedentary behavior during childhood predict adolescents' positive MH. To the best of our knowledge, there are no studies that are representative for German adolescents.
The predominantly cross-sectional studies that have been conducted thus far make it impossible to draw any temporal (or causal) conclusions about an MH-protecting or -enhancing mechanism of PA or about negative MH associations caused by ST. Regarding ST, a study using the SDQ (see Methods section) revealed over a 2-year period that ST was negatively associated with prosocial behavior and positively associated with hyperactivity, peer problems, and conduct problems and that high ST was related to the development of emotional symptoms in young children and to the development of hyperactivity and conduct problems in older children. A recent 2-year longitudinal study revealed better MH in active adolescents than in sedentary adolescents, whereas MH decreased over time independently of participants' activity levels. The authors concluded that changing from a physically active profile to a sedentary profile was associated with a significantly greater decrease in MH than was keeping active, whereas changing to an active profile attenuated the decrease in MH. Moreover, findings from 2 recent meta-analyses suggested that increased PA and decreased sedentary behavior enhanced MH in children and adolescents.[26,27] One of the challenges of conducting longer-term cohort studies of media and technology use, like studies of ST and MH, is the rapidly changing technology landscape.
Taken together, there is a need to 1) investigate the longitudinal relationships of PA and ST with MH outcomes in children and adolescents and 2) examine both PA and ST concurrently, as both factors have been shown to be independent but related lifestyle behaviours. Furthermore, a concomitant investigation allows for accounting for the interrelationship between these 2 factors and for distinguishing the independent and interactive effects of PA and ST on MH. Longitudinal studies suggest that an increase in PA and a decrease in sedentary behavior during childhood predict adolescents' MH. In the current study, we aimed to investigate the relationships among PA, ST, and MH in a longitudinal sample of German schoolchildren over a period of 11 years.
Am J Epidemiol. 2021;190(2):220-229. © 2021 Oxford University Press