Neuropsychological predictors of driving errors in older adults.

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 (aged 65-89; mean age 72.3) and 80 middle-aged drivers (aged 40-64; mean age 57.2).

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 according to video review using a standardized taxonomy.

RESULTS

Older drivers committed an average of 35.8 +/- 12.8 safety errors per drive, compared with an average of 27.8 +/- 9.8 for middle-aged drivers (P<.001). For older drivers, there was an increase of 2.6 errors per drive observed for each 5-year age increase (P=.03). After adjustment for age, education, and sex, COGSTAT was a significant predictor of safety errors in older drivers (P=.005), with an approximately 10% increase in safety errors observed for a 10% decrease in cognitive function. Individual significant predictors of more safety errors in older drivers included poorer scores on the Complex Figure Test--Copy, the 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. Age-related decline in cognitive abilities, vision, and motor skills can explain some of this increase. Changes in visuospatial and visuomotor abilities appear to be particularly associated with unsafe driving in old age.