Abstract
The aim of this study was to determine the functional deficits that predict particular types of driving difficulties among older drivers. A sample of 90 drivers 60 years and older completed a battery of functional (psychological, visual, physical, cognitive, and attentional) tests and a standardized on-road driving test. Driving errors were classified into a set of 7 distinct categories (positioning, gap selection, incorrect speed, observation, speed of approach, mirror, and indicator), and correlation and regression analyses were used to determine the best functional predictors of specific error types. As expected, functional deficits were more strongly related to some error types (eg, positioning errors) than others (eg, failure to indicate). Measures of visual attention were associated with a broad range of error types, and particularly, with errors prompting an intervention from the driving instructor, suggesting that a deficit in visual attention is a key indicator of the likelihood of driving problems. Errors in speed of approach to intersections or before undertaking driving maneuvers appear to be related to problems with vision.