Running head: DIFFERENTIATING HIGH RISK AND LOW RISK ADHD DRIVERS 1 Human Factors and Driving Behaviors Differentiating High Risk and Low Risk Drivers with Attention Deficit Hyperactivity Disorder

Compared to non-clinical individuals, younger drivers with Attention Deficit Hyperactivity Disorder are at a greater risk for traffic accidents. There is a wide range of human factors contributing to driving competence that are impaired in this population, stemming from the core symptoms of inattention, impulsivity and hyperactivity. The goal of the present study was to identify specific driving behaviors that contribute to a greater risk for adverse driving events for ADHD drivers. The present study utilized a DriveCam recording system to monitor driving of 17 young adult ADHD drivers over three months. The seven High Risk ADHD drivers, those with a collision during the observation period, were primarily differentiated from the Low Risk ADHD drivers by inattentive and distracted behaviors. DIFFERENTIATING HIGH RISK AND LOW RISK ADHD DRIVERS 3 Human Factors and Driver Behaviors Differentiating High Risk and Low Risk Drivers with Attention Deficit Hyperactivity Disorder Attention Deficit Hyperactivity Disorder (ADHD) is characterized by deficits in sustained attention, resistance to distraction, voluntary motor inhibition and regulation of activity levels relative to same-aged individuals (American Psychiatric Association, 2001; Barkley, 2006). For those with ADHD, these deficits impact many functional domains, resulting in adverse effects on social relationships, community functioning, and educational and vocational success (Barkley, Fischer, Smallish, & Fletcher, 2004; Mannuzza & Klein, 1999). Originating in early childhood, ADHD is a relatively persistent condition with up to 80% of diagnosed children continuing to meet diagnostic criteria in adolescence (Barkley, Fischer, Edelbrock, & Smallish, 1990; Weiss & Hechtman, 1993) and up to 67% continuing into adulthood (Barkley, Fischer, Smallish, & Fletcher, 2002). Although the core symptoms of inattention, impulsivity and hyperactivity may show improvement into adulthood, many associated problems and impairments persist. These enduring difficulties expand into functional realms requiring greater responsibility, including work performance, sexual relationships, substance dependence or abuse, and driving (Barkley, Fischer, Smallish, & Fletcher, 2004; Mannuzza & Klein, 1999). In addition to the symptom-based deficits that negatively impact many functional domains for this population, individuals with ADHD also have a greater propensity to engage in risky behaviors compared to their peers. Farmer and Peterson (1995) found that adolescents with ADHD not only anticipated less severe consequences following risky behavior but also reported fewer active methods of preventing injury compared to matched controls. The researchers reasoned that cognitive factors such as a lowered expectation of personal risk in hazardous DIFFERENTIATING HIGH RISK AND LOW RISK ADHD DRIVERS 4 situations and a minimized capacity to generate prevention strategies contributed to the increased injury liability found for the ADHD sample. Furthermore, adolescents and young adults with ADHD are more likely to be involved with deviant peer groups and certain social pressures associated with this negative affiliation, which has been linked to an increase in risk taking for these individuals (Marshal, Molina & Pelham, 2003). Marshal, Molina and Pelham found that deviant peer affiliation mediated the relationship between ADHD and substance use, suggesting that adolescents and young adults with ADHD are more likely than those without ADHD to become involved with deviant peers and, as a result, more likely to use illegal substances. Furthermore, the researchers found that the relationship between deviant peer affiliation and substance use was stronger for those with ADHD: once immersed in a deviant peer group, adolescents and young adults with ADHD are more vulnerable to negative social influences. Driving is one of the most concerning domains in which the specific symptom-based deficits, the increased tendency towards risky behaviors, and the greater vulnerability to negative social influences may be particularly deleterious for adolescents and young adults with ADHD. Therefore, the present study is primarily concerned with elucidating the specific impairments in safe driving behaviors and the overall increased driving risk for young adults with ADHD.