Psychological Distress, Television Viewing, and Physical Activity in Children Aged 4 to 12 Years

METHODS

RESULTS

Table 1 represents characteristics of the sample split into thirds of TVSE time. Approximately 25% of the sample engaged in TVSE for at least 3 hours/day, and the mean (± SD) TVSE time was 2.4 ± 1.4 hours/day. Children who engaged in higher TVSE time were more likely to be older, boys, have a higher index of deprivation, lower physical activity, and have poorer dietary intake (lower fruit and vegetable consumption, and more frequent intake of sweets, confectionary, and fizzy drinks). Approximately 20% of children suffered from a chronic medical condition, and in 50% of cases this was asthma or skin-related complaints. Chronic medical conditions were, however, not associated with TVSE time.

An abnormally high SDQ total difficulties score (20–40) was found in 4.2% of the sample and 6.5% were borderline (score of 16–19), using previously recommended bandings.²⁶ A higher total SDQ difficulties score was related to higher TVSE time and lower physical activity levels (see Table 2). In general linear models, both TVSE time and physical activity remained independently associated with the SDQ total difficulties score, after adjustment for age, gender, index of deprivation, single-parent status, chronic medical conditions, and various dietary indicators (see Table 3). Other independent predictors of the SDQ total difficulties score included gender (girls had lower scores than boys; regression coefficient β = −0.78 [95% confidence interval (CI): −1.33 to −0.22]), age (12-year-olds had lower scores than 4-year-olds; β = −1.61 [95% CI: −2.70 to −0.52]), deprivation (more highly deprived children had higher scores; β = 3.38 [95% CI: 2.49–4.28]), single-parent status (children of single-parent families had higher scores; β = 2.18 [95% CI: 1.55–2.82]), medical conditions (children with existing medical conditions had higher scores; β = 2.10 [95% CI: 1.41–2.74]), and fruit and vegetable intake (children with greater intake had lower scores, highest compared with lowest third; β = −0.83 [95% CI: −1.53 to −0.12]). In separate models, adjustment for psychosocial and demographic factors partly attenuated the associations of TVSE time and the SDQ score, although other covariables had negligible impact (see Table 3). In addition, we performed logistic regression analyses to examine if TVSE time and physical activity were associated with abnormal SDQ scores (≥16). In fully adjusted models, the highest TVSE time group was associated with increased odds of abnormally high psychological distress (odds ratio: 1.45 [95% CI: 0.94–2.25]) in comparison with the lowest TVSE group. The lowest physical activity group was also associated with increased odds of abnormally high psychological distress (odds ratio: 1.64 [95% CI: 1.02–2.61]) in comparison with the highest physical activity group.

In additional analyses we examined the interaction of TVSE time and physical activity level on the SDQ score. There was a significant additive interaction between TVSE time and physical activity (P < .001). Under a linear model, these results reflect an additive interaction, displayed in a “joint effects” approach. Table 4 presents adjusted regression coefficients for each group in comparison with the reference group (high TVSE/low physical activity). Figure 1 demonstrates that the highest SDQ scores were in the most sedentary children with the highest TVSE times. In fact, higher TVSE exposure (>2.7 hours/day) alone resulted in a 24% increase in the SDQ score in comparison with lower TVSE exposure (<1.6 hours/day), although when combined with low physical activity this resulted in a 46% increased score.

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FIGURE 1

Association between psychological distress, TVSE time, and physical activity. Gray bars represent the lowest TVSE time, black bars represent the medium TVSE time, and white bars represent the highest TVSE time.

DISCUSSION

The main findings from this study demonstrate that TVSE time and physical activity level are independently associated with psychological distress in young children. In addition, higher levels of TVSE time and low physical activity levels interact to increase psychological distress. Although TVSE time and physical activity were inversely associated, the results suggest that these factors operate independently and also synergistically to increase risk. Our findings are consistent with previous research that showed independent effects of sedentary behavior and physical activity on the SDQ total difficulties score in 13- to 16-year-old adolescents.⁹ Previous studies in children aged 4 to 12 years have shown positive associations of physical activity with male gender, self-efficacy, parental physical activity, and parental support,¹⁸ although we are unaware of any studies to date that have examined physical activity and psychological distress in this age group. Therefore, the present study extends existing knowledge in this area.

There is accumulating evidence for an adverse effect of TVSE viewing on the mental health and behavior of young people.^2–8 Several interventions designed to reduce children's exposure to TVSE have demonstrated encouraging effects, such as a reduction in aggressive behavior.⁴ In another controlled trial, reduced TVSE time and increased physical activity resulted in improved levels of self-efficacy in French adolescents,²⁷ although it was not clear if an increase in activity or reduction in sedentary time was responsible for these effects. Exposure to TVSE has been shown to cause various physiologic responses in children, such as arousal of the central nervous system,²⁸ and can also affect sleep patterns.⁸ These mechanisms might partly account for the psychological disturbances associated with TVSE exposure. Physical activity is associated with better brain health possibly by altering the metabolism of various neurotransmitters and enhancing growth factors.²⁹ In a previous study, cardiovascular autonomic responses to playing a computer game differed in physically trained compared with untrained preadolescent boys.³⁰ Thus, physical activity may alter psychophysiological responses to TVSE exposure and partly reduce the risk of psychological ill effects.

The limitations of the present study should be recognized. Given the cross-sectional nature of this study, we cannot exclude the possibility that the present results are explained by reverse causality or confounding from unmeasured variables, such as overall quality of diet. For example, parents might allow poorly behaved children to spend more time viewing TVSE as a means of regulating their behavior. An increase in television viewing, which is presumably the larger component of TVSE, may result in increased consumption of fast food and calorie-dense snacks.³¹ Poor dietary habits have been shown to adversely affect mental wellbeing.³² We did, however, adjust our analyses for some indicators of unhealthy eating habits and a number of potential confounders such as socioeconomic factors and medical conditions. In addition, our TVSE and physical activity data are based on parental proxy measures, which might have affected the results. However, a recent study demonstrated that adolescents' reports of their own physical activity levels were highly correlated with parental ratings of their teenager's activity,⁹ and we have also reported evidence for convergent validity of the physical activity measures used in the present study. Therefore, our findings should be replicated and extended by using objective measures of physical activity. We did not specifically examine if the content or context of TVSE might have influenced SDQ scores independently of viewing time, which might be an important factor.^7,33

CONCLUSIONS

Given that high TVSE time and low physical activity both independently predicted abnormally high SDQ scores, our results might be clinically meaningful and have relevance for practitioners. This is the first study, to our knowledge, to demonstrate that higher levels of TVSE and low physical activity interact to increase psychological distress in younger children (aged 4–12 years). Measured physical activity seems to decrease significantly between the ages of 9 and 15.³⁴ Because physical activity levels in adolescence also predict mental health in adulthood,¹⁷ public health policy should focus on reducing sedentary time and maintaining sufficient physical activity levels in younger children.