Adolescents' stress and depressive symptoms and their associations with psychological flexibility before educational transition.

INTRODUCTION: Relatively little is known about individual differences in adolescent psychological flexibility and its associations with symptoms of stress and depression. This study examined different profiles of adolescent stress and depressive symptoms and their associations with developing psychological flexibility before the critical educational transition. METHODS: The data were derived from a general sample of 740 Finnish ninth-grade adolescents (Mage = 15.7 years, 57% female) who were assessed twice during the final grade of their basic education. The data were analyzed using growth mixture modeling. RESULTS: Four profiles of stress and depressive symptoms were identified during a school year: (1) no stress and no depressive symptoms (None; 69%); (2) mild and decreasing stress and depressive symptoms (Decreasing; 15%); (3) low but increasing stress and depressive symptoms (Increasing; 6%); and (4) high and stable levels of stress and depressive symptoms (High; 10%). The adolescents in these profiles differed from each other in their initial levels and changes of psychological flexibility. The initial level of psychological flexibility was highest in the no-symptom profile group. We observed simultaneous change trends in symptoms and psychological flexibility during a school year. When symptoms decreased, psychological flexibility increased, and when symptoms increased, psychological flexibility decreased. CONCLUSIONS: A bidirectional pattern of relationships between psychological flexibility and psychological symptoms was found. Despite initially high level of skills in psychological flexibility, some adolescents, unexpectedly, experienced increased symptoms of stress and depression during the school year. The results call for further studies to explore in-depth the developmental diversity in adolescents' well-being and its antecedents.