Somatic Factors Predict On-Road Driving Skills in Older Drivers and Drivers with Mild Cognitive Impairment.

Background: On-road driving skills can be impaired in older drivers and drivers with mild cognitive impairment (MCI) due to different driving-relevant deficits. Among these deficits, somatic factors have received little attention so far.

Methods: In a prospective observational on-road driving study, we examined whether somatic factors can predict on-road driving skills in a mixed sample of healthy older drivers and drivers with MCI (n = 99) and whether the inclusion of age explains additional variance. Somatic factors included the number of prescribed drugs, visual acuity, peripheral visual field integrity, mobility of the cervical spine, and hearing impairment. A hierarchical regression analysis was used to predict on-road driving skills by adding the somatic factors in the first step and age in the second step.

Results: Results revealed that the combination of somatic factors significantly predicted on-road driving skills (R2adjusted = 0.439). The inclusion of age led to a significant increase of explained variance (R2adjusted = 0.466).

Conclusions: Our results suggest that somatic factors can accurately predict on-road driving skills in healthy older drivers and drivers with MCI. In addition, our results suggest that there is a significant but rather small effect of age beyond somatic changes.