Long-term adverse outcomes and resilience of individuals who misused substances as adolescents

Abstract

Background: Little is known about the long-term outcomes in multiple domains of adult functioning of individuals who as adolescents misused substances. The goal of this thesis was to examine adverse and resilient outcomes through 30 years of adulthood of individuals who as adolescents had consulted a clinic for substance misuse problems and to identify risk and protective factors present in adolescence that distinguished trajectories of adult development.

Method: Data were used from a longitudinal project, the Consequences of Antisocial Behaviour in Adolescence (CASBA), a follow-up study documenting adult outcomes of two cohorts of individuals who were treated for substance misuse as adolescents and a general population sample matched on age, gender, and birth place. Cohort 1 consisted of 1992 individuals who were treated from 1968 to 1971 while Cohort 2 consisted of 1576 individuals who were treated from 1980 to 1984. Information about the clinic sample in adolescence was extracted from the old clinic files while information about adult outcomes was obtained from national registers.

Results: Eight main findings emerged. One, individuals who as adolescents had consulted a clinic for substance misuse problems, as compared to the general population sample, were significantly more likely to experience adverse outcomes defined as death, physical illness, mental illness, substance misuse, criminality, and poverty, during the subsequent 30 years. Two, not only did the clinic sample experience high levels of adversity in each outcome domain, they also experienced adversity in multiple domains of adult functioning. Three, among the individuals who as adolescents had engaged in substance misuse distinct developmental trajectories of resilience over 25 years of adulthood were identified. Four, factors operating in adolescence were associated with outcomes throughout three decades of adulthood. Five, substance misuse in adulthood appeared to drive criminal offending. Six, treatment received at the clinic in adolescence was not associated with resilience in adulthood. Seven, few differences in adult outcomes were found between Cohort 1 and 2. Eight, while gender differences in the risk of adverse outcomes were observed and gender independently predicted the adverse outcomes, no gender differences were observed in trajectories of resilience through adulthood, few gender differences were observed in the great majority of the associations of risk and protective factors with outcomes. Female gender was found to be protective against criminal offending.

Conclusions: Adolescence is a critical life period. Both risk factors and protective factors present in adolescence impact outcomes in adulthood. Gender is associated with distinct adult outcomes but not with the accumulation of adverse outcomes or developmental trajectories of resilience in adulthood. The concept of resilience requires modification to take account of the findings that resilience is dynamic and changes over the life course and that it differs across domains of functioning. Defining distinct sub-types of adolescent substance misusers is a necessary first step to identifying causal mechanisms. Substance misuse may play a major role in promoting criminal offending in adulthood.