Identification of elderly drivers whose crash involvement risks are alleviated by passenger presence

It is essential to find measures to compensate for the decline in elderly drivers' driving ability in order to meet their mobility needs and ensure their safety when driving. Although it has been well documented that elderly drivers' risks of crash involvement are alleviated by the presence of passengers, few studies have investigated whether the protective effect of passengers is influenced by driver characteristics including the degree of cognitive impairment. This study aimed to identify subgroups of elderly drivers whose crash involvement risks are more effectively alleviated by passenger presence. After dividing elderly drivers into three levels of cognitive impairment, as measured by the Short-Memory Questionnaire, and two gender groups, the present study found that only male drivers in the middle cognitive level benefited from passenger presence. The effectiveness of passenger presence may be more successfully achieved by proper selection of the appropriate range of cognitive decline and gender.