Motor Vehicle Crash Risk in Older Adult Drivers With Attention-Deficit/Hyperactivity Disorder

Key Points Question Is crash risk associated with attention-deficit/hyperactivity disorder (ADHD) in older adult drivers? Findings In this cohort study of 2832 active drivers aged 65 to 79 years, the lifetime prevalence of ADHD was 2.6%. Having ADHD was associated with a 7% increased risk of hard-braking events, a 102% increased risk of self-reported traffic ticket events, and a 74% increased risk of self-reported vehicular crashes. Meaning Given this finding that ADHD is associated with a significantly increased crash risk in older adult drivers, improved diagnosis and clinical management of ADHD to promote safe mobility and healthy aging are warranted.


Introduction
Attention-deficit/hyperactivity disorder (ADHD) is a chronic neurodevelopmental condition with symptoms such as inattentiveness, impulsivity, and hyperactivity. 1 Although ADHD is commonly considered a childhood disorder, it can persist into adulthood and affect daily life performances of older adults. 2,3[6] The reported prevalence of ADHD in adults has increased in recent years due to improved diagnosis.Data from the National Ambulatory Medical Care Survey indicated a 2-fold increase in the diagnosis of ADHD in adults compared with youth from 2008-2009 to 2012-2013. 7Similarly, a longitudinal study found a 4-fold increase in the diagnosis of ADHD in adults compared with children from 2007 to 2016. 8Although concerns remain about contributing factors for the reported increase in adult cases of ADHD, there is mounting evidence that the prevalence of ADHD in adults has increased in recent years. 9In general, the prevalence of ADHD decreases with advancing age, as only approximately 30% of children with ADHD have persistent symptoms throughout their life span. 10[12] Major symptoms of ADHD may impair cognitive functioning, including complex executive functioning in activities of daily living, such as driving.Previous research showed a positive association between ADHD and unsafe driving behaviors based on self-, informant, and official reports. 13For on-road driving outcomes, drivers with ADHD were more prone to receive license suspensions and speeding tickets and to be involved in vehicular crashes. 14A meta-analysis found that having ADHD was associated with an 88% increased risk in self-reported motor vehicle crashes. 15Experimental studies using driving simulators revealed that participants with ADHD had higher average speed, more frequent lane changes, worse vehicle control, a greater likelihood of collisions with an obstacle, and a higher propensity of other adverse driving outcomes than participants without ADHD. 16,17Risk factors, such as heightened anxiety, could contribute to adverse driving outcomes, such as traffic citations, of individuals with ADHD. 18Moreover, potentially inappropriate medication use is associated with unsafe driving behaviors, as older drivers take more medications than younger drivers. 19However, it remains unclear whether the association of polypharmacy use with crash risk is similar between drivers with and without ADHD.
The proportion of the US licensed driver population accounted for by older adults (ie, those aged 65 years or older) increased from 13% in 2011 to 17% in 2020. 20It is well established that older adult drivers have substantially higher fatal crash rates per mile driven than drivers aged 30 to 59 years. 21Despite the aging US driver population and the increasing prevalence of ADHD in adults, research on ADHD and driving safety is limited primarily to adolescents and young adults. 17,18Few studies have assessed the association of ADHD with crash risk among older adults.In this study, we aimed to examine the prevalence of ADHD and test the hypothesis that ADHD is associated with a significantly increased motor vehicle crash risk in older adult drivers.California). 21Each site recruited approximately the same number of study participants. 21Driving data, such as hard-braking events and total miles driven, were collected for up to 44 months through an in-vehicle data recording device (DataLogger; Danlaw, Inc) installed to an accessible on-board diagnostics II port in the participant's primary vehicle at the time of enrollment.

JAMA Network Open | Geriatrics
The eligibility criteria for participating in the LongROAD project were as follows: aged 65 to 79 years at baseline with a valid driver's license, driving at least once a week on average, residing in the study site catchment area for at least 10 months a year, having no plans to move outside of the catchment area within 5 years, having access to a motor vehicle of the model year 1996 or newer with an accessible on-board diagnostics II port, driving 1 vehicle approximately 80% of the time or more if having access to more than 1 vehicle, being fluent in English, and scoring 4 or higher on the Six-Item Screener. 21Older adults with significant cognitive impairment or Alzheimer disease and related dementias were not eligible for enrollment. 21Excluded from this study were 138 participants due to missing data on ADHD status, 19 participants due to missing driving data, and 1 participant due to unreliable data on hard-braking events, yielding 2832 participants for analysis.
An annual questionnaire consisting of driving, health, and functioning domains was used to collect self-reported data, such as demographic characteristics, driving performance, and health behaviors.The brown-bag review method was used to collect data on medications and supplements, which were coded according to the pharmacologic and therapeutic classification system established by the American Society of Health-System Pharmacists in the American Hospital Formulary Service Clinical Drug Information. 22formed consent was obtained from participants, and a certificate of confidentiality was obtained from the National Institutes of Health.The study protocol was approved by the institutional review boards of all involved institutions.The design and methods of the LongROAD project are described in detail elsewhere. 21While preparing this article, we followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline.

ADHD
The exposure of interest was self-reported lifetime ADHD recorded at baseline.As part of the health and behavior assessment, participants were asked if they have ever had or ever been told by a physician or other health professional that they had "attention-deficit disorder/ADD" or "attentiondeficit/hyperactivity disorder/ADHD."An affirmative answer to the question was coded as having ADHD.Data on attention-deficit disorder and ADHD were combined in this study because attentiondeficit disorder is no longer a separate diagnosis according to the Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition). 23Self-reported lifetime diagnoses of depression and anxiety were collected at baseline.

Outcomes of Interest
The outcome of primary interest was hard-braking events, which were defined as maneuvers with deceleration rates of 0.4g or higher.Secondary outcomes included self-reported traffic violations and crashes collected during the annual follow-up assessment.Data for self-reported traffic ticket events were collected from answers to the question, "How many times in the past year have you received a traffic ticket, other than a parking ticket, where you were found to be guilty, regardless of whether you think you were at fault?" Data for self-reported crashes were collected from answers to the question, "How many accidents have you been involved in over the past year when you were

Covariates
Demographic and health characteristics were obtained through in-person visits at the study sites.
Self-reported data related to age (categorized as 65-69 years, 70-74 years, and 75-79 years), sex, race and ethnicity (categorized as non-Hispanic Black, non-Hispanic White, and other), marital status, highest degree or level of education, annual household income in total, and urbanicity (classified by Rural-Urban Commuting Area Code) were collected during baseline visits.Self-reported race and ethnicity were recorded because fatality rates from motor vehicle crashes vary considerably across racial and ethnic groups. 24The other racial and ethnic group included small numbers of Asian, Native and Indigenous American, and Hispanic participants.

Statistical Analysis
Statistical analysis was performed between July 15, 2022, and August 14, 2023.The sample size of the LongROAD project was estimated to generate adequate person-time of observation for ensuring a study power of more than 80% in detecting a crash incidence rate ratio (IRR) of 3.0 or greater. 21e post hoc powers for detecting the differences at the P = .05level between drivers with and without ADHD in the incidence rates of hard-braking events, traffic ticket events, and vehicular crashes per mile driven were 100%, 97%, and 96%, respectively.Pearson χ 2 tests were used to examine differences in the prevalence of ADHD across covariates.Incidence rates of hard-braking events per 1000 miles driven and self-reported traffic ticket events and vehicular crashes per 1 million miles driven were computed according to baseline demographic characteristics, number of medications the participant was taking, comorbidities (anxiety and depression), and ADHD.Crude IRRs for hard-braking events were computed by dividing the total number of hard-braking events by the total miles driven in each stratum of participant characteristics.Due to overdispersion, multivariable negative binomial modeling was used to estimate adjusted IRRs (aIRRs) and 95% CIs of the 3 outcomes, with miles driven as the offset.A 2-tailed P < .05 was considered statistically significant.For parsimoniousness of the models, only statistically significant covariates were included.All data analyses were performed using SAS OnDemand for Academics, version 3.81 software (SAS Institute Inc).

Results
Of

Discussion
The results of this prospective cohort study indicate that the prevalence of ADHD in US older adult drivers between July 2015 and March 2017 was 2.6%, compatible to the prevalence reported in the Netherlands (2.8%) and Sweden (3.3%). 25,26Furthermore, we found that ADHD was associated with increased risks of hard-braking events and self-reported traffic ticket events and vehicular crashes among older adult drivers.Extending prior research in adolescent and young adult drivers, [16][17][18][19] our findings show that older adults with ADHD may experience an elevated risk of adverse driving outcomes compared with their counterparts without ADHD.9][30][31] In alignment with our results, older adults with ADHD did not show statistically significant differences in sex, income, education, or urban residence compared with their counterparts without ADHD. 25Our results are consistent with previous reports that anxiety and depression may be closely linked to ADHD. 8,11,12,25Although the prevalence of ADHD declines with advancing age, 2,25,32 the increased risk of comorbidities, such as anxiety and depression, could contribute to reduced life expectancy in these individuals.It is noteworthy that the associations between ADHD and all 3 adverse driving safety outcomes remained significant even when adjusting for these associated disorders.
Young adults with ADHD tend to overestimate their driving ability and performance since this disorder can lead to diminished self-assessment and awareness. 14Older adults with ADHD might have similar issues in evaluating their own driving behaviors due to impaired executive functioning, thus leading to higher driving risks.Drivers with ADHD may have difficulty remaining alert and have a decreased reaction time, resulting in a higher likelihood of collision with obstacles. 17In our study, older adult drivers with ADHD had excess risks of self-reported traffic ticket events and vehicular crashes that were greater than the excess risk of hard-braking events.[35][36] Our study also showed a threshold effect of the level of polypharmacy on the risk of adverse driving outcomes.Nonstimulant pharmacologic treatments for ADHD, such as atomoxetine, have been shown to be effective in improving symptoms as well as reducing driving errors, 37,38 but it is unclear whether reducing polypharmacy use might have beneficial effects on driving performance.Some stimulant pharmacologic medications, such as methylphenidate, 14,39,40 have been found to improve ADHD symptoms and help alleviate driving errors compared with placebo.A recent study, however, found increased odds of vehicular crashes for individuals treated with stimulants. 41search supports that although drivers with ADHD who do not take medication may experience The estimated aIRRs of hard-braking events were adjusted for marital status, annual household income, urbanicity, depression, and number of medications; estimated aIRRs of traffic ticket events were adjusted for marital status, urbanicity, and depression; and estimated aIRRs of vehicular crashes were adjusted for sex, annual household income, urbanicity, anxiety, and depression.Issues of underdiagnosis and treatment of ADHD in older adults still exist. 10Challenges of diagnoses include late emergence of obvious symptoms in adulthood and recall bias of childhoodonset symptoms in older adults. 43Late-life cognitive disorders, such as dementia, could obfuscate the diagnosis of ADHD due to shared pathogenic features. 10,44Meanwhile, the current Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) criteria 45 for ADHD only specify the threshold or the number of applicable symptoms for diagnosis in children, adolescents, and adults, without giving special consideration to older adults.Given its association with driving safety alone, ADHD in older adults merits greater attention.

Limitations
This study has several limitations.First, ADHD status was based solely on self-report, which may make the results susceptible to recall bias.Moreover, data on current ADHD symptoms and severity were not available.Second, the LongROAD project participants were not a nationally representative sample since they were disproportionately non-Hispanic White with relatively high levels of educational attainment and household income.Therefore, our findings may not be generalizable to the US older adult driver population.Third, despite being widely used in naturalistic driving studies, [33][34][35][36] hard-braking events and self-reported traffic ticket events as proxies for unsafe driving behaviors limit the ability to draw causal inferences between ADHD and crash risk.Finally, our results are based on observational data and could be somewhat biased by unmeasured confounders, such as weather and road conditions.

Conclusions
The results of this cohort study indicate that the lifetime prevalence of ADHD in older adult drivers was 2.6%.Older adult drivers with ADHD may be at elevated risks of hard-braking events, traffic ticket events, and vehicular crashes.As aging of the driver population continues, effective interventions to improve the diagnosis and clinical management of ADHD among older adults are warranted to promote safe mobility and healthy aging.

2023 Methods Study Sample The
Motor Vehicle Crash Risk in Older Drivers With Attention-Deficit/Hyperactivity Disorder Longitudinal Research on Aging Drivers (LongROAD) project was a multisite, prospective cohort study of 2990 active drivers aged 65 to 79 years at baseline.The sample was recruited between July 6, 2015, and March 31, 2017 from primary care clinics or health care systems in 5 sites (Ann Arbor, JAMA Network Open.2023;6(10):e2336960. doi:10.1001/jamanetworkopen.2023.36960(Reprinted) October 4, 2023 2/11 Downloaded From: https://jamanetwork.com/ on 10/07/ All data related to the 3 outcomes of interest were collected during the first 3 years of follow-up (ending onMarch 31, 2019).The response rates during the follow-up were 96.6% in the first year, 94.1% in the second year, and 93.9% in the third year.