Overall, drivers with Parkinson disease (PD) had poorer road safety compared to controls, but there was considerable variability among the drivers with PD, and some performed normally. Familiarity with the driving environment was a mitigating factor against unsafe driving in PD. Impairments in visual perception and cognition were associated with road safety errors in drivers with PD.

Objectives To identify neuropsychological factors associated with driving errors in older adults. Design Cross-sectional observational study. Setting Neuropsychological assessment laboratory and an instrumented vehicle on a 35-mile route on urban and rural roads. Participants One hundred eleven older adult drivers (ages 65-89 years; mean age 72.3 years) and 80 middle-aged drivers (age 40 to 64 years; mean age 57.2 years). Measurements Explanatory variables included age, neuropsychological measures (cognitive, visual, and motor), and a composite cognitive score (COGSTAT). The outcome variable was the safety error count, as classified by video review using a standardized taxonomy. Results Older drivers committed an average of 35.8 safety errors/drive (SD=12.8), compared to an average of 28.8 (SD=9.8) for middle-age drivers (P<0.001). Among older drivers, there was an increase of 2.6 errors per drive observed for each five-year age increase (P=0.026). After adjustment for age, education, and gender, COGSTAT was a significant predictor of safety errors in older drivers (P=0.005), with approximately a 10% increase in safety errors observed for a 10% decrease in cognitive function. Individual significant predictors of increased safety errors in older drivers included poorer scores on Complex Figure Test-Copy, Complex Figure Test-Recall, Block Design, Near Visual Acuity, and the Grooved Pegboard task. Conclusion Driving errors in older adults tend to increase, even in the absence of neurological diagnoses. Some of this increase can be explained by age-related decline in cognitive abilities, vision, and motor skills. Changes in visuospatial and visuomotor abilities appear to be particularly associated with unsafe driving in old age.

Objective: To determine the incidence of and risk factors for driving outcomes in drivers with Parkinson disease (PD). Methods:In a prospective cohort study, we ascertained the time until driving cessation, a crash, or a traffic citation using self-report and state Department of Transportation records in 106 licensed, active drivers with PD and 130 controls.Results: Drivers with PD stopped driving earlier than controls, hazard ratio (95% confidence interval) ϭ 7.09 (3.66-13.75), p Ͻ 0.001. Cumulative incidence of driving cessation at 2 years after baseline was 17.6% (11.5%-26.5%) for PD and 3.1% (1.2%-8.1%) for controls. No significant differences between groups on times to first crash or citation were detected. However, the number of observed crashes was low. Cox proportional hazards models showed that significant baseline risk factors for driving cessation in PD were older age, preference to be driven by somebody else, positive crash history, use of compensatory strategies, low driving exposure, impairments in visual perception (especially visual processing speed and attention) and cognitive abilities, parkinsonism (especially activities of daily living score and total daily dose of antiparkinsonian medications), and higher error counts on a road test. Within PD, crashes were associated with poorer postural stability and history of driving citations, and citations were associated with younger age and road errors at baseline. Conclusions:Drivers with PD are at a higher risk of driving cessation than elderly control drivers. A battery evaluating motor and nonmotor aspects of PD, driving record, and performance can be useful in assessing future driving outcomes in PD. Neurology Cognitive, visual, and motor impairments in Parkinson disease (PD) can affect driving performance on standardized road tests 1-11 and driving simulator experiments. 12-16 Cross-sectional or retrospective surveys show higher rates of driving cessation in PD, 17-21 which may lead to greater inactivity, social isolation, depression, and caregiver burden. 22,23 Driving simulation studies have shown increased crash rates in PD 13,16 and retrospective surveys have suggested increased crashes in drivers with PD. 17,19 However, real-life driving outcomes in PD have not been determined in prospective, controlled PD cohort studies. 21This study examines the real-life outcomes in a PD driver cohort, whose baseline features, experimental road test, and driving simulator performance were reported previously. 1,5,6,8,16 The main outcome measures in this study were time to driving cessation, time to first crash, and time to first citation. We hypothesized that the incidence of unfavorable real-life driving outcomes in drivers with PD would be higher than in neurologically normal control drivers,

Decline in cognitive abilities can be an important contributor to the driving problems encountered by older adults, and neuropsychological assessment may provide a practical approach to evaluating this aspect of driving safety risk. The purpose of the present study was to evaluate several commonly used neuropsychological tests in the assessment of driving safety risk in older adults with and without neurological disease. A further goal of this study was to identify brief combinations of neuropsychological tests that sample performances in key functional domains and thus could be used to efficiently assess driving safety risk. 345 legally licensed and active drivers over the age of 50, with either no neurologic disease (N=185), probable Alzheimer's disease (N=40), Parkinson's disease (N=91), or stroke (N=29), completed vision testing, a battery of 10 neuropsychological tests, and an 18 mile drive on urban and rural roads in an instrumented vehicle. Performances on all neuropsychological tests were significantly correlated with driving safety errors. Confirmatory factor analysis was used to identify 3 key cognitive domains assessed by the tests (speed of processing, visuospatial abilities, and memory), and several brief batteries consisting of one test from each domain showed moderate corrected correlations with driving performance. These findings are consistent with the notion that driving places demands on multiple cognitive abilities that can be affected by aging and age-related neurological disease, and that neuropsychological assessment may provide a practical off-road window into the functional status of these cognitive systems.

This study aimed to develop predictive models for real-life driving outcomes in older drivers. Demographics, driving history, on-road driving errors, and performance on visual, motor, and neuropsychological test scores at baseline were assessed in 100 older drivers (ages 65–89 years [72.7]). These variables were used to predict time to driving cessation, first moving violation, or crash. Using Cox proportional hazards regression models, significant individual predictors for driving cessation were greater age and poorer scores on Near Visual Acuity, Contrast Sensitivity, Useful Field of View, Judgment of Line Orientation, Trail Making Test-Part A, Benton Visual Retention Test, Grooved Pegboard, and a composite index of overall cognitive ability. Greater weekly mileage, higher education, and “serious” on-road errors predicted moving violations. Poorer scores from Trail Making Test-Part B or Trail Making Test (B-A) and serious on-road errors predicted crashes. Multivariate models using “off-road” predictors revealed (1) age and Contrast Sensitivity as best predictors for driving cessation; (2) education, weekly mileage, and Auditory Verbal Learning Task-Recall for moving violations; and (3) education, number of crashes over the past year, Auditory Verbal Learning Task-Recall, and Trail Making Test (B-A) for crashes. Diminished visual, motor, and cognitive abilities in older drivers can be easily and noninvasively monitored with standardized off-road tests, and performances on these measures predict involvement in motor vehicle crashes and driving cessation, even in the absence of a neurological disorder.

Automobile driving is a safety-critical real-world example of multitasking. A variety of roadway and in-vehicle distracter tasks create information processing loads that compete for the neural resources needed to drive safely. Drivers with mind and brain aging may be particularly susceptible to distraction due to waning cognitive resources and control over attention. This study examined distracted driving performance in an instrumented vehicle (IV) in 86 elderly (mean = 72.5 years, SD = 5.0 years) and 51 middle-aged drivers (mean = 53.7 years, SD = 9.3 year) under a concurrent auditory-verbal processing load created by the Paced Auditory Serial Addition Task (PASAT). Compared to baseline (no-task) driving performance, distraction was associated with reduced steering control in both groups, with middle-aged drivers showing a greater increase in steering variability. The elderly drove slower and showed decreased speed variability during distraction compared to middle-aged drivers. They also tended to “freeze up”, spending significantly more time holding the gas pedal steady, another tactic that may mitigate time pressured integration and control of information, thereby freeing mental resources to maintain situation awareness. While 39% of elderly and 43% of middle-aged drivers committed significantly more driving safety errors during distraction, 28% and 18%, respectively, actually improved, compatible with allocation of attention resources to safety critical tasks under a cognitive load.

BACKGROUND Our ability to predict aging related declines in driving performance from off-road assessments have clinical practice and social policy implications. OBJECTIVES 1) To describe longitudinal changes in mean-level and evaluate rank-order stability in potential predictors of driving safety (visual sensory, motor, visual attention, and cognitive functioning) and safety errors during an 18-mile on-road-drive-test among older adults. 2) To evaluate the relative predictive power of earlier visual sensory, motor, visual attention, and cognitive functioning on future safety errors controlling for earlier driving capacity. DESIGN A three-year longitudinal observational study; SETTING A large teaching hospital in the Mid-West; PARTICIPANTS 111 neurologically normal older adults (60 to 89 years at baseline); MEASUREMENTS Safety errors based on video review of a standard 18-mile on-road driving test served as the outcome measure. Comprehensive battery of tests on the predictor side included visual sensory functioning, motor functioning, cognitive functioning, and a measure of Useful Field of View. RESULTS Longitudinal changes in mean-levels of safety errors and cognitive functioning were small from year-to-year. Relative rank-order stability between consecutive assessments was moderate in overall safety errors, it was moderate to strong in visual attention and cognitive functioning. While prospective bivariate correlations ranged from fair to moderate between safety errors and predictors, only functioning in the cognitive domain predicted future driver performance one and two-years later in multivariate analyses. CONCLUSION Normative aging related declines in driver performance as assessed by on-road tests emerge slowly. The findings clearly demonstrated that even in the presence conservative controls, such as previous driving ability, age, visual sensory and motor functioning, cognitive functioning predicted future driving performance on-road one and two-years later.

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