Background: With driving while impaired by alcohol (DWI) representing a persistent burden on global health, better understanding and prevention of recidivism following a first-time DWI conviction are needed. Progress towards these goals is challenged by the marked heterogeneity in offender characteristics and a traffic safety literature that relies on subjective self-report measures and cross-sectional study designs. The present study tested the hypothesis that an objective neurobiological marker of behavioural maladjustment, the cortisol stress response (CSR), predicts future DWI and other traffic convictions over a 9-year follow-up period.
Methods: One hundred thirty-two male first-time DWI offenders and 31 non-offender comparators were recruited and assessed at intake for their substance use, psychosocial and psychological characteristics and CSR. Traffic conviction data were obtained from provincial driving records. Survival analysis estimated the association between CSR and risk of a traffic conviction over time.
Results: In support of our hypothesis, blunted CSR predicted traffic convictions during the follow-up duration. This effect generalized to both DWI offenders and non-DWI drivers. While CSR was lower in DWI offenders compared to non-offenders, it did not specifically predict recidivism in DWI offenders. Modelling results indicated that blunted CSR, along with DWI offender group membership, experience seeking and drug use frequency, may demarcate a high-risk driver phenotype.
Conclusions: CSR is a neurobiological marker of a driver phenotype with elevated generalized driving risk. For drivers with characteristics consistent with this phenotype, expanding the focus of intervention to address multiple forms of risky driving may be necessary to curb their overall threat to traffic safety.
Keywords: Alcohol; Cortisol; Impaired driving; Offenders; Prediction; Stress response; Survival analysis.