Driving with Attention-Deficit/ Hyperactivity Disorder: Influences of Demand and Arousal in Real Traffic

Abstract

Previous research has indicated a critical role of task demand in determining driving outcomes amongst individuals with attention-deficit/ hyperactivity disorder (ADHD). These findings are derived predominantly from laboratory simulations. The objective of the present study therefore was to investigate the relationship between factors influencing demand and arousal in real traffic, and the performance of drivers medicated (n = 15) and unmedicated for ADHD (n = 12), compared to a control group (n = 17). Self-reported data relating to risky driving behaviours and driving history, and symptoms of ADHD in adulthood were collected. To determine the influence of demand on driving performance and errors, participants navigated a route incorporating rural, urban, residential, and highway environments. Relative to controls, unmedicated ADHD drivers employed fewer safe driving skills (p < .05), committed more inattentive (p < .05), and impatient driving errors (p < .01), and reported engaging in more frequent aggressive violations (p < .05). ADHD was associated with higher rates of crashes (p < .01) and multiple crashes (p = .05). Attesting to the efficacy of stimulant treatment, medicated ADHD driver performance in the present study was comparable to, if not better than controls. While unmedicated drivers undervalued the risk related to driving behaviours predictive of poor outcomes, medicated ADHD drivers largely overestimated the severity of their risky driving (p < .01). Demand was found to significantly impact the performance of unmedicated ADHD drivers particularly. Attention was best during high demand, urban driving. As environmental demand declined, more frequent attentional lapses occasioned increased impairment to performance (p < .01). Relative to drivers of automatic vehicles, high demand manual driving was linked with better hazard detection (p < .05) and overall performance (p < .05) amongst medicated drivers, and safer following distances amongst unmedicated ADHD drivers (p < .05). Apparently distinct driving styles were also revealed between ADHD subtypes. This is the first study to document the impact of factors influencing task demand on ADHD driver performance in real traffic. Further exploration of the present findings could prove fundamental for future strategies of behavioural intervention.