(PS1-A1) Childhood Family Instability and Young-adult Substance Use Disorder: Pathways Through Peer Involvement

Research suggests that childhood family instability (i.e., multiple transitions in family structure) increases risk for later substance use and disorder (Blake et al., 2021; Keller et al., 2002; Krohn et al., 2009).  However, little is known about the mechanisms underlying this association. One possibility is that family instability increases youth’s time spent with peers (Rebellon, 2002). Moreover, effects on substance use disorder (SUD) may be further moderated or mediated by affiliation with substance-using peers. Finally, these pathways may differ for youth with and without a family history of SUD.

The present study examined mediated and moderated associations of childhood family instability with young adult SUD, using a longitudinally-followed sample (N=454) of adolescents in families oversampled for familial SUD. Approximately half were male, half had a biological parent with an alcohol or drug disorder, and one-third were Hispanic/Latinx, with the remainder being non-Latinx White. First, we tested a sequential mediation model, in which family instability through early adolescence (sum of changes in family structure) predicted higher odds of young adult DSM-IV SUD diagnosis through greater time spent with peers and subsequent exposure to substance-using peers in adolescence. Second, we tested a moderated mediation model, in which family instability predicted greater time spent with peers, and effects of time spent with peers on SUD were moderated by peer substance use. Finally, we tested two multigroup models, in which each of the former models were compared in youth with and without a family history of SUD. Covariates were gender, ethnicity, age, and earlier levels of substance use and peer substance use. Analyses were conducted in MPlus, using FIML for missing data.

The sequential mediation model was supported, and results differed based on familial SUD (95% CIs for index of moderated mediation: .003, .048). In youth without a family history of SUD, family instability increased time spent with peers, which predicted greater exposure to substance-using peers, which then predicted increased odds of SUD (CIs for sequential indirect effect: .005, .047). However, among youth with familial SUD, time spent with peers was high regardless of family instability, so subsequent exposure to substance-using peers and later SUD risk were also high (CIs for sequential indirect effect: -.002, .006). There was no significant interaction between time spent with peers and peer substance use, and no three-way interaction with familial SUD.

Family instability may “set off” risk for SUD in the absence of prior familial SUD risk. Although a similar “vulnerable-stable” pattern (Luthar et al., 2000) has been found in previous research (Blake et al., 2023), no studies to date have identified mediators of this effect. For lower risk youth (without familial SUD), family instability may increase adolescents’ time spent with peers (perhaps by undermining the parent-child relationship), and therefore facilitates greater exposure to peer substance use, ultimately increasing risk for later SUD. These findings inform preventative interventions for SUD by highlighting modifiable mediators for SUD risk among a subset of youth exposed to family instability.