Are child and adolescent mental health problems increasing in the 21st century? A systematic review

Objective: Up to one in five children experience mental health problems. Social and cultural factors may influence emergence of mental health problems. The 21st century has led to changes in many of these factors, but it is unclear whether rates of internalizing and externalizing problems have also changed in recent cohorts of young people. Methods: A comprehensive literature search was undertaken to locate cohort or population studies that examined changes in mental health of children over time, where participants were aged 18 years and under, and the time frame for change was at least 10 years, with data for at least one time point in the 21st century being statistically compared to at least one time point in the 20th century. Studies were reviewed for quality and outcome. Results: Nineteen studies met criteria for review. These included studies of toddlers, children, and adolescents. Seventeen studies examined internalizing problems, and 11 studies examined externalizing problems. For both children and toddlers, recent cohorts did not exhibit worsening of mental health symptoms. In adolescents, the burden of externalizing problems appear to be stable. However, the majority of studies report an increase in internalizing problems in adolescent girls. The findings for internalizing problems in boys were mixed. Conclusions: These findings suggest that recent cohorts of adolescent girls are experiencing increases in internalizing symptoms compared to previous cohorts. Approaches for prevention and early intervention should be explored.