Research That Matters (January 17 - 20, 2008)

Introduction: A surfeit of research exists examining the prevalence of substance use, mental illness and violence in both children and adolescents in addition to antecedents affecting these outcomes. While the study of these outcomes in both isolation and combination is well developed for children and adolescents, the same cannot be said for the commensurate study of their co-occurrence for young adults. This gap has implications for both the theoretical understanding and implementation of directed interventions for young adults exhibiting these negative outcomes. Accordingly, this study utilizes a sample of 21 year olds (N=605) to: (1) examine the prevalence of the co-occurrence of substance use, mental illness and violence and document the different groupings of the outcomes; and (2) investigate the relationship between various theoretically-indicated risk factors and the co-occurrence of substance use, mental illness and violence.

Method: This study utilizes data collected from the Seattle Social Development Project. Analyses are restricted to 21 years old participants. Of the 605 respondents, 53.8% (n=324) were nonwhite and 48.9% (n=296) were male. This study examined various combinations of the co-occurrence of violence, substance use, and mental health disorder. Independent variables were chosen based on social development theory in addition to prior clinical and epidemiological studies of risk factors related to outcomes of the co-occurrence of problems that may be associated with sociodemographic characteristics, attitudes, behaviors and other relevant life events. Multinomial logit analysis was used to examine the association between demographic, attitudinal and familial characteristics in addition to recent life events and various co-morbid conditions.

Results: Overall, our findings indicate that the prevalence of substance use, use of multiple substances, violence, and mental illness was surprisingly low among community-based 21 year olds. While the overall percentages were low, some gender differences were identified. Females were more likely to report co-occurrence of substance use and mental illness and males were more likely to engage in the overall majority of the outcomes. The multivariable analysis supported the bivariate relationships indicating that factors from each domain (demographic, attitudinal, household and recent life events) significantly increase the likelihood of reporting co-occurring problem behaviors. Those reporting co-occurring conditions were more likely to report stressful life events.

Implications: While the magnitude is broad, the consequences of substance use are equally problematic for persons with mental illness, which are correlated with: treatment non-adherence, multiple hospitalizations, violence, victimization, risky sexual behaviors and involvement in the criminal justice system. Furthermore, the social and treatment costs associated with co-morbid substance use and mental illness remain a primary social and health care issue. Clustering of these problems presents significant challenges for both clinicians and clients alike; one perhaps best indicated by the trend for psychosocial interventions to address only one outcome at a time and which may in turn exacerbate negative outcomes. It is therefore imperative to gain a better understanding of not only the prevalence of co-morbid outcomes for young adults, but also the correlates of said outcomes.