Attention Deficit Hyperactivity Disorder Symptoms and Previous Diagnosis, Other Comorbidities and Driving: Population-based Examination in a Canadian Sample

Author(s): Evelyn Vingilis, Jane Seeley, Robert E. Mann, Patricia Erickson, Maggie Toplak, Nathan Kolla

Slidedeck Presentation Only (no paper submitted):

3C - Vingilis


In some studies Attention Deficit Hyperactivity Disorder (ADHD) has been associated with increased risky driving, traffic offences and collisions. However, most studies used clinical samples. Thus, questions about the relationships among ADHD symptoms, previous diagnosis, other psychiatric symptoms, substance abuse and driving-related outcomes need to be explored.

To examine the relationships among ADHD symptoms, previous diagnosis, other psychiatric symptoms, substance abuse and driving-related outcomes among a provincially representative sample of adults 18 years and older living in the province of Ontario, Canada.

The Centre for Addictions and Mental Health (CAMH) Ontario Monitor is an ongoing repeated cross-sectional telephone survey of Ontario adults which includes validated measures: ADHD measures (Adult ADHD Self-Report Scale-V1.1, previous ADHD diagnosis, ADHD medication use); psychiatric distress (anxiety/depression) measures (General Health Questionnaire, anxiety/depression/pain medication use); antisocial behaviour measure (The Antisocial Personality Disorder Scale from the Mini-International Neuropsychiatric Interview); substance abuse (Alcohol Use Disorders Identification Test, Alcohol, Smoking and Substance Involvement Screening Test); driving-related outcomes (driving after drinking, driving after cannabis use, road rage, collisions in past year) and socio-demographics (gender, age, km travelled). This study presents statistically weighted results of a 3-year study.

5818 Ontario residents were interviewed, with 203 (3.5%) screening positively for ADHD symptoms. Data were aggregated into ADHD+ screen/previous diagnosis (n = 33 (0.6%)); ADHD+ screen/no previous diagnosis (n = 170 (2.9%)); ADHD- screen/previous diagnosis (n = 120 (2.1%)) and ADHD- screen/no previous diagnosis (n = 5495 (94.4%)). Key results indicated that those with previous diagnosis were more likely to be male, aged 18-24 and report antisocial behaviours (ADHD+ screen/previous diagnosis = 37.9%; ADHD- screen/previous diagnosis = 9.3%). Those with current ADHD+ screen were more likely to report psychiatric distress, using prescribed anti-anxiety, anti-depressant and pain medication in last year.
Regarding driving outcomes, no between group differences were found for driving after drinking and collisions in past year. However, a higher percent of ADHD- screen/previous diagnosis respondents (8.4%) reported driving a motor vehicle within an hour of using cannabis, marijuana or hash, compared to those with ADHD+ screen/previous diagnosis (3.0%), ADHD+ screen/no previous diagnosis (2.4%) and ADHD- screen/no previous diagnosis (1.7%). Also a higher percent (26.7%) of ADHD+ screen/previous diagnosis respondents reported road rage (threatened to hurt a driver or passenger in another vehicle or threatened to damage their vehicle compared with those who screened ADHD compared to ADHD+ screen/no previous diagnosis (2.5%); ADHD- screen/previous diagnosis (4.6%) and ADHD- screen/no previous diagnosis (0.9%). Additional analyses will be conducted to control for age, gender and driving exposure and to examine more fully profiles of the four groups.

This population-based study of a representative sample of adults living in Ontario shows that when the data are aggregated into probable, possible and no ADHD some driving-related differences emerge.

More externalizing behaviours, including aggressive driving and cannabis use and driving are associated with previous ADHD diagnosis. However, these analyses are based on self-report screeners and not psychiatric diagnoses. Thus, these results should be interpreted with caution.