Physical activity and mental health in children and adolescents: An updated review of reviews and an analysis of causality

Highlights

• Systematic reviews on physical activity and depression, self-esteem, and cognitive functioning in youth have expanded.

• There is evidence for a causal association between physical activity and cognitive functioning in young people.

• There is partial evidence for a causal association between physical activity and depression in young people.

• There is no evidence for a causal association between physical activity and self-esteem in youth, but the field is complex.

Abstract

Objectives

Evidence concerning physical activity and mental health remains less well documented for children and adolescents. An updated review of systematic reviews and meta-analyses was undertaken concerning physical activity and mental health in children and adolescents, and to judge the extent to which associations can be considered causal.

Methods

Systematic reviews and meta-analyses were identified to update our previous review of reviews (Biddle & Asare, 2011), with papers identified between November 2010 and the end of 2017. Criteria were used to judge causality (Hill, 1965), including strength of association, dose-response association, and experimental evidence.

Results

Since 2011, the quantity (k = 42 reviews) and quality of research has increased in depression (evidence from 10 reviews), self-esteem (10 reviews) and cognitive functioning (25 reviews). Anxiety had only three new, small, reviews. Intervention effects for depression are moderate in strength while observational data show only small or null associations. Variable effect sizes are evident from interventions for the reduction of anxiety and improvement in self-esteem. Higher or improved fitness and physical activity are associated with better cognitive health and performance. There was partial support for a causal association with depression, a lack of support for self-esteem, but support for cognitive functioning.

Conclusions

There are significant increases in research activity concerning physical activity and depression, self-esteem, and cognitive functioning in young people. The strongest evidence for a causal association appears to be for cognitive functioning, and there is partial evidence for depression.

Introduction

Mental health has no universal definition, however key issues include those of depression and anxiety, which have been shown to have high prevalence rates among young people (see below). Furthermore, self-esteem is considered a key indicator of mental health, including emotional stability and subjective well-being (Lindwall & Acsi, 2014), and is a strong focus for educational programs for young people. Moreover, cognitive functioning is an important element of child development and has gained increasing traction in recent years, including in the context of physical activity (Davis & Lambourne, 2009).

Data from developed countries suggest that the mental health of many young people is less than optimal. Ireland, Portugal, Germany, and Finland have the highest rates of reported depression in Europe for those aged 15 years and over, all with greater than 10% prevalence rates for chronic depression (Eurostat Statistics Explained, 2018). The Mental Health Foundation reports 2014 data showing that 19.7% of people in the UK aged 16 years and over showed symptoms of anxiety or depression. This was a 1.5% increase from the previous year, and rates appear to be higher among females (Mental Health Foundation, 2018).

In Australia, the latest data (2008–09) suggest that there have been 1.2 million mental health-related general practice encounters for young people (aged 16–24 years) annually, and that this has increased by 21% during the 2000s. The most frequently managed mental health problems concern depression and anxiety (Australian Institute of Health and Welfare, 2011). Moreover, the second National Survey of the Mental Health and Wellbeing of Australian Children and Adolescents, conducted 2013–14, reported that a mental disorder was experienced by 14% of children and adolescents aged 4–17 years, including major depressive and anxiety disorders (Lawrence et al., 2015).

Based on these statistics, it is important to be able to identify potential low cost strategies for improving mental health for young people across the population. Physical activity is often suggested as one such approach (Ekkekakis, 2013). Links between physical activity and psychological benefits have been made over many centuries and even back into antiquity. In an early academic paper, Layman (1974) stated that the psychological benefits of physical activity had been “a part of the literature … for over 2000 years” but that claims “were often quite extravagant, without the benefit of supporting scientific evidence” (p. 33) (Biddle & Vergeer, 2018). While the field has expanded considerably over the past 30–40 years, it remains replete with simplistic statements and lacks a more nuanced approach that recognises its inherent complexity. For example, it is common to see assertions in national guidelines and educational contexts that physical activity in essentially ‘good’ for young people without recognising that positive mental health benefits may depend on the experience of physical activity and the context it takes place in. However, the identification of underlying mechanisms explaining changes in mental health as a result of changes in physical activity levels remains imprecise. That said, a number of interacting neuro-biological, psychological, and social mechanisms are thought to be at play, including changes to the structure and function of the brain, changes to feelings of competence and confidence, and opportunities for positive social interaction and growth (Biddle, Mutrie, & Gorely, 2015).

As the research field develops better evidence, it is important to synthesise current findings to assist with optimal mental health promotion efforts. Moreover, it is important to focus on young people because of the important developmental issues faced during this life stage.

In January 2011, the International Olympic Committee (IOC) convened a meeting on ‘Fitness & Health of Children through Physical Activity and Sport’. Invited experts reviewed and summarised evidence and a consensus paper was published alongside individual topic reviews (Mountjoy et al., 2011). In evaluating the evidence linking involvement in physical activity with mental health in young people, Biddle and Asare (2011) conducted a review of reviews concerning depression, anxiety, self-esteem, and cognitive functioning. However, with continued interest and developments concerning the health of young people, and regular production of national and international physical activity guidelines, it is important to update the evidence, given that Biddle and Asare (2011) synthesised findings from reviews dating from 1986 to 2010 and the number of reviews available then was limited.

In addition to summarising evidence from more recent reviews, it is important to investigate whether any associations between physical activity and mental health outcomes in youth can be considered causal. This was not done in the 2011 review. Assessing causality requires appraisal of the evidence on a number of criteria, such as those proposed by Sir Austin Bradford Hill (Hill, 1965). Typically, assessments are made concerning strength of association, consistency, temporal sequencing, coherence and biological plausibility, dose-response association, and experimental evidence. While commentaries on physical activity and mental health in adults have used these criteria (Dishman, Heath, & Lee, 2013; Mutrie, 2000), they are lacking for young people.

Consequently, the purpose of this paper is to update the review of reviews by Biddle and Asare (2011). In addition, we assess whether each mental health outcome addressed can be considered to be causally associated with physical activity in children and adolescents. In the 2011 paper, we also reviewed primary studies concerning sedentary behaviour and mental health in youth. Given that systematic reviews are only just emerging on this topic (see Hoare, Milton, Foster, & Allender, 2016; Suchert, Hanewinkel, & Isensee, 2015), we have not provided an update in the current paper.