Patients with mild to moderate Parkinson disease showed impaired visual perception and cognition compared with elderly control subjects. Visual dysfunction contributes to parkinsonian disability through its influences on cognition and locomotion.

Drivers with Alzheimer disease (AD) exhibit a range of performance on tests of cognition, vision, and motor skills. Since these tests provide additional predictive value of driving performance beyond diagnosis alone, clinicians may use these tests to help predict whether a patient with AD can safely operate a motor vehicle.

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.

The cognitive and visual deficits associated with PD resulted in impaired visual search while driving, and the increased cognitive load during this task worsened their driving safety.

Drivers with Alzheimer disease made more errors than neurologically normal drivers on a route-following task that placed demands on driver memory, attention, and perception. The demands of following route directions probably increased the cognitive load during driving, which might explain the higher number of safety errors.

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.

The quantitative effect of an auditory-verbal distracter task on driving performance was not significantly different between Parkinson disease (PD) and control groups. However, a significantly larger subset of drivers with PD had worsening of their driving safety errors during distraction. Measures of cognition, motor function, and sleepiness predicted effects of distraction on driving performance within the PD group.

No abstract