Cognitive Change and Driving Behavior among Older Drivers

Per vehicle miles traveled, older adults have a high fatal crash rate. One factor is dementia. This study aims to assess how differences in cognition affect driving behavior among older drivers. We analyzed data from the Health and Retirement Study. Our study used cognition, demographics, and driving behavior from 2006 to 2014 for respondents aged 65 and above. Three levels of driving behavior were measured: whether the individual could drive, whether they had driven in the past month, and whether they drove long distances. Cognitive function was measured through the Telephone Interview for Cognitive Status. Additionally, individuals were coded as having no diagnosis of dementia, a diagnosis within 2 years, or a diagnosis more than 2 years previously. We estimated the likelihood of each driving behavior in association with cognition using a modified Poisson regression model for binary outcomes. Among respondents (N = 16,061), 79% could drive. Of these, 93% had driven in the past month, and of these, 64% drove long distances. Compared with no impairment, mild impairment was associated with a significant 12% decrease in probability of being able to drive, an 8% decrease in driving within the past month, and a 24% decrease in driving long distances. The decrease was larger among those with severe impairment. Results were in a similar direction and strength comparing individuals without dementia with individuals 0 to 2 years after diagnosis, and to more than 2 years after diagnosis. A strong positive association exists between lower cognition and lower driving exposure.