Associations Between Adolescent Mental Health and Health-Related Behaviors in 2005 and 2015: A Population Cross-Cohort Study

Purpose: Adolescent mental ill-health is a growing concern. There is little understanding of changes over time in the associations between mental health and health-related behaviors and outcomes (such as substance use, antisocial behavior, and obesity). We investigate whether the associations between different health and health-related outcomes in adolescence are changing over time in two recent cohorts of adolescents born 10 years apart. Methods: Data from two UK birth cohort studies, the Avon Longitudinal Study of Parents and Children (ALSPAC, born 1991–92, N = 5,627, 50.7% female) and Millennium Cohort Study (MCS, born 2000–2, N = 11,318, 50.6% female) at age 14 are analyzed. The health outcomes of focus are depressive symptoms, substance use (alcohol, smoking, cannabis, and other drugs), antisocial behaviors (assault, graffiti, vandalism, shoplifting and rowdy behavior), weight (body mass index [BMI]), weight perception (perceive self as overweight), and sexual activity (had sexual intercourse). Regression analyses are conducted to examine associations between these variables with cohort as a moderator to examine cohort differences. Results: The directions of associations between mental-health and health-related behaviors (e.g., smoking) are similar over time; however, their strength across the distribution has changed. While smoking and alcohol use behaviors are decreasing in adolescents, those that endorse these behaviors in 2015 are more likely to have co-occurring mental ill-health than those born in 2005. Similarly, higher BMI is more strongly associated with depressive symptoms in 2015 compared to 2005. Conclusions: Adverse health-related outcomes such as greater substance use, mental health difficulties, and higher BMI appear to be more likely to cluster together in the more recent cohort, with implications for public health planning, service provision, and lifelong disease burden