Influence of physical activity, sedentary behavior, and diet quality in childhood on the incidence of internalizing and externalizing disorders during adolescence: a population-based cohort study

Purpose: Studies among youth suggest that physical inactivity, sedentary behaviors, and poor diet quality are associated with poor mental health. Few population-based studies have investigated these relationships longitudinally. We examined the association between physical activity, sedentary behaviors, and diet quality in childhood and the incidence of internalizing and externalizing disorders throughout adolescence. Methods: We linked health behavior survey data from 2003 among 10- to 11-year-old children across Nova Scotia, Canada, with administrative health care data from 2003 to 2011. Students' diet quality was assessed using the Harvard Food Frequency Questionnaire. Physical activity and sedentary behaviors were self-reported, and internalizing and externalizing disorders were diagnosed by a physician. We applied Cox regression to examine the associations of the health behaviors with the incidence of internalizing and externalizing disorders between 2003 and 2011. Results: Of the 4861 participating students, 23.7% and 9.4% had a diagnosis of internalizing and externalizing disorders, respectively. The incidences of internalizing and externalizing disorders were higher among students who were less physically active and spent more time using computers and video games. Conclusions: These findings suggest that promoting an active lifestyle in childhood may contribute to the prevention of both internalizing and externalizing disorders during adolescence. (C) 2017 Elsevier Inc. All rights reserved.