Road Rage: Old Wine in a New Bottle / Reply: Ancient Wine but Still Potent?

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Dear Editor: In driving research, the debate about the relevance of temperamental factors and psychopathology has a long history. Tillman and Hobbs' classic 1949 article, "The Accident Prone Automobile Driver," is the first in the psychiatric literature to describe a link between psychiatric illness and driving problems (1). These researchers recruited 96 drivers who had 4 or more accidents and compared them with accident-free drivers. Clinical evaluation showed that the accident repeaters were "more aggressive, impulsive, resentful of authority and lacking in social responsibility." The authors coined the phrase, often repeated in the literature , that "a man drives as he lives." The debate continues.

Smart and others' timely article "Psychiatric Distress Among Road Rage Victims and Perpetrators" (2) raises several important points regarding underlying psychopathology in this condition. Intermittent explosive disorder is a condition that falls within the impulse-control disorder spectrum. One of the most common categorical diagnoses that underlie impulsecontrol disorder in adults is attention-deficit hyperactivity disorder (ADHD)-often unrecognized. A good developmental history would usually reveal a childhood diagnosis of this condition. This is significant: the bestdocumented evidence for psychiatric illness and impulsive driving relates to ADHD (3,4). This differential diagnosis of impulsivity is very important with regard to clinical management. We now have evidence from Cox and others that, in driving simulator studies, stimulant medication significantly improves driving performance by subjects with uncontrolled ADHD, as well as preliminary evidence that stimulants may also improve driving behaviour on the road (5). Jerome and Segal reported on 100 consecutively presenting patients with ADHD (6). Some 80% of these had ADHD, including a combination of both inattentive and hyperactive and impulsive symptoms (combined type). Self-report and collateral data collected with a structured interview questionnaire, the Jerome Driving Questionnaire, indicated that subjects with ADHD, combined type, experienced high levels of frustration and impulsive behaviours in relation to other drivers on the road. Their reported driving behaviours fulfilled the criteria for road rage described by Smart and others (2). Cloninger's Temperament and Character Inventory was used to establish personality profiles from this group and a similar group of patients with ADHD, combined type, attending an outpatient clinic at the Centre for Addiction and Mental Health. These profiles showed a high prevalence of externalizing personality disorder (7; personal communication, Dr Umcsh Jain, 2003). When treated with stimulants, these patients described a parallel improvement on the JDQ and resolution of ADHD symptoms.

Impulsivity also occurs in a range of unconnected categorical conditions that have their common pathway of expression through deficits in executive function (8). For example, impulsivity as a chronic intermittent condition may well reflect chronic emotional lability, which often is seen as part of chronic dysthymia or borderline personality organization or, less often, reflects a frank mood disorder. Stimulant medication would not be expected to improve emotionally based impulsivity; it would more likely worsen it.

The current Canadian Medical Association guidelines on driving safety include road rage as a subcategory of emotional disorder (9). The latest edition includes ADHD as a reportable condition if it is uncontrolled and associated with impulsive driving. Impulsive road rage may reflect separate orthogonal variables of cognitive impulsivity and emotional lability, which may require quite different treatment modalities. Further careful research into this nonspecific syndrome, which appears to be presenting with increasing prevalence, seems to have merit, both for public health measures and, possibly, for psychiatric practice. …