Internalizing Symptoms: Effects of a Preventive Intervention on Developmental Pathways from Early Adolescence to Young Adulthood

This study examined the mediated and moderated effects of a universal family-focused preventive intervention, delivered during young adolescence, on internalizing symptoms assessed in young adulthood. Sixth grade students (N=446; 52% female; 98% White) and their families from 22 rural Midwestern school districts were randomly assigned to the experimental conditions in 1993. Self-report questionnaires were administered at seven time points (pre-test to young adulthood-age 21) to those receiving the Iowa Strengthening Families Program (ISFP) and to the control group. Results showed that growth factors of adolescent internalizing symptoms (grades 6-12) were predicted by ISFP condition and risk status (defined as early substance initiation). Moderation of the condition effect by risk status was found, with higher-risk adolescents benefitting more from the ISFP. Results also supported the hypothesis that the ISFP's effect on internalizing symptoms in young adulthood was mediated through growth factors of adolescents' internalizing symptoms; risk moderation, however, was only marginally significant in young adulthood. The relative reduction rate on clinical or subclinical levels of young adult internalizing symptoms was 28%, indicating that for every 100 young adults displaying clinical or subclinical levels of internalizing symptoms from school districts not offering an intervention, there could be as few as 72 displaying those levels of symptoms in school districts that offered middle school prevention programming. These findings highlight how the positive effects of family-focused universal interventions can extend to non-targeted outcomes and the related potential public-health impact of scaling up these interventions.     

Testing a Model of Universal Prevention Effects on Adolescent Relationships and Marijuana Use as Pathways to Young Adult Outcomes

There are several interrelated knowledge gaps in the literature on skills-building interventions for middle schoolers designed to prevent initiation of substance use, all of which concern the limited study of the adolescent pathways of those intervention effects on distal young adult outcomes. Among the most important yet understudied pathways of influence on long-term effects are positive youth relationship outcomes of middle-school interventions. Other influential pathways for long-term effects are reductions in adolescent substance misuse, particularly marijuana use, considering the long-term consequences of early marijuana initiation. To address these knowledge gaps, data from a randomized controlled trial were used to test a longitudinal, developmental model positing pathways of intervention effects on age 21 illicit drug use and positive relationship affect, via earlier effects on adolescent relationships and marijuana use. Sixth-graders and their families enrolled in 22 Iowa schools were randomly assigned to the Iowa Strengthening Families Program or a control group (N?=?446). The average age of students at baseline was 11.3 years (10–13 year age range); 48% were male and 98% were Caucasian, reflective of the demographics in the participating rural Midwest communities. Measures included middle-school relationships (parents, peers, school), high school marijuana use, plus age 21 illicit drug use and relationship affect (parents, work, school), 10 years past intervention implementation. As expected, intervention effects on young adult variables were indirect, through effects on adolescent outcomes, with higher-risk participants showing greater intervention impact. The findings suggest preventive interventions with young adolescents have potential to demonstrate effects into young adulthood.