The Role of Top-Down Attentional Control and ADHD Symptoms in Predicting Future Motor Vehicle Crash Risk

OBJECTIVE: ADHD confers elevated risk for automobile crashes, both as a clinical syndrome and continuously when examining risk as a function of symptom severity. However, the neurocognitive mechanisms and processes underlying this risk remain poorly understood. The current longitudinal study examined whether attention network components reflect neurocognitive pathways linking ADHD symptoms with adverse driving outcomes. METHOD: Prospective monitoring of objectively-identified crashes, near-crashes, and crash fault in 3,226 drivers from six U.S. sites participating in the Strategic Highway Research Program (SHRP-2) Naturalistic Driving Study. At study entry, drivers were assessed for ADHD symptoms, completed the Conners’ CPT-II, and were then followed continuously for 1-2 years of routine, on-road driving using technology-enhanced in-car monitoring. Bias-corrected, bootstrapped mediation models examined the extent to which attention network components mediated the association between ADHD symptoms and future driving risk, controlling for known risk factors. RESULTS: As expected, self-reported ADHD symptoms predicted all markers of future driving risk. Higher ADHD symptoms were associated with reduced inhibitory control, lower levels of top-down attentional control (endogenous orienting), and greater arousal decrements (phasic alertness). Controlling for ADHD symptoms, top-down attentional control uniquely predicted future crashes, near-crashes, and culpability for future crashes/near-crashes; only arousal decrements portended future near-crashes. Only top-down attentional control significantly mediated the association between baseline ADHD symptoms and future driving risk. CONCLUSIONS: The driving risks associated with ADHD appear to be conveyed in part by impairments in the top-down, voluntary control of attention, rather than to difficulties sustaining attention over time or inhibiting impulses as is often assumed.