Introduction: Impulsivity is a risk factor for addiction, including stimulants. The precise mechanisms through which impulsivity conveys risk is unclear. Identifying these mechanisms could inform targeted intervention. bioSocial Cognitive Theory (bSCT) hypothesises two mechanistic pathways linking dimensions of impulsivity to addiction. The first predicts that higher reward drive/sensitivity leads to the development of more positive drug outcome expectancies, encouraging problematic use. The second pathway predicts that a greater propensity to act without forethought (rash impulsiveness) leads to reduced confidence in one's ability to resist rewards, which include drugs (low refusal self-efficacy), encouraging problematic use. bSCT has received empirical support in studies of alcohol and cannabis use.


Purpose: This study tests bSCT in a stimulant treatment population.


Method: 151 stimulant users (73.5% methamphetamine; 19.2% cocaine) attending a specialist outpatient clinic in an Australian tertiary-level public hospital were administered a battery of questionnaires assessing impulsivity, social cognition, and severity of dependence (SDS). Data were analysed using structural equation modelling with robust maximum likelihood estimation to test bSCT predictions.


Results: The hypothesised model explained 51.8% variance in severity of stimulant dependence and showed good fit to the data, chi-square= 29.195, df= 12, p= .004, CFI= 0.956; RMSEA= 0.098; SRMR= 0.067). Lower stimulant refusal self-efficacy mediated the effects of higher rash impulsiveness and positive expectancies on dependence severity. Positive stimulant expectancies mediated the effects of higher reward drive.


Conclusions: Findings support bSCT in stimulant addiction, highlighting the potential importance of stimulant refusal self-efficacy as a treatment target and identifying potential biosocial cognitive factors influencing it.