Adolescent Preventive Intervetion Effects on Age 22 Depression Symptoms Extended to Age 25 Quality of Life Measures

Introduction:  Earlier research has demonstrated family and school preventive intervention effects on non-targeted depression symptoms at age 22, mediated through relationship problems and illicit use of substances at age 21. However, there is a gap in the research regarding subsequent effects on more general quality of life measures. We predicted that the interventions’ indirect effects on depression symptoms at age 22 would influence quality of life variables at age 25, including (1) job satisfaction, (2), stress, and (3) subjective well-being. We tested a SEM model that examined those mediated influences.

Method:  Students enrolled in 36 rural Iowa schools participated in a randomized controlled trial consisting of three conditions: (1) school-based LifeSkills Training [LST] plus the family-focused Strengthening Families Program: For Parents and Youth 10-14 interventions; (2) LST-only and; (3) a control group. Students completed in-home assessments at baseline (N=670) and were followed through age 25. The current model extends earlier research by assessing indirect effects of the interventions on the age 25 quality of life measures, mediated by age 21 relationship problems and illicit use of substances and, in turn, age 22 depression symptoms. Control variables assessed at baseline were adolescent substance initiation, parents’ and adolescents’ depression symptoms, and sex. The intervention groups were combined and compared with the control group because no significant differences were found between the two intervention conditions on structural paths or on the depression symptoms outcome. SEM analyses with manifest and latent variables were conducted with MPlus 7.11, using the MLR estimator, to assess indirect intervention effects; FIML was used to address missing data.

Results: The SEM model fit the data well (χ² ₍₂₅₈₎ = 372.319, p<.001; CFI=960; RMSEA=.026). Analyses showed significant indirect effects of the combined intervention groups on age 25 job satisfaction (β=.008, t=2.130, p=.033), stress (β=-.018, t=-2.288, p=.022) and subjective well-being (β=.013, t=2.354, p=.019), mediated through the indirect effects on age 21 relationship problems and illicit use of substances, and, in turn, indirect effects on age 22 depression symptoms (β=-.044, t=-2.467, p=.014). 

Conclusions:  Participation in preventive interventions primarily targeting substance misuse during early adolescence has the potential to improve quality of life in young adulthood through cross-over effects on a range of important areas of young adult development. Results support the broad-spectrum, long-term effects of appropriately-timed universal preventive interventions.