Cognitive impairment and gender show more impact on driving cessation than dementia biomarkers

A study of when and why older adults decide to stop driving found that a diagnosis of cognitive impairment or poor cognitive test results were bigger factors than brain imaging and cerebrospinal fluid biomarkers of dementia. Additionally, female participants were about four times more likely to stop driving than their male counterparts. Led by Washington University in St. Louis investigators, the study results were published in Neurology.

The research team studied 283 participants, 51% of whom were women, with an average age of 72 who drove at least once a week and did not have cognitive impairment at the beginning of the study. Participants took cognitive tests when the study began and then annually for an average of 5.6 years. During the study, people who developed cognitive impairment were more likely to stop driving than those who maintained baseline cognitive health or had better cognitive test results.

Participants also received brain scans and had cerebrospinal fluid samples taken at the start of the study, then again every two to three years. Participants were not informed of their cognitive test scores or their dementia biomarker status.

While approximately one third of participants met the criteria for preclinical Alzheimer's disease as determined by biomarkers such as amyloid plaques and tau tangles, the results showed that the presence of Alzheimer's biomarkers (in addition to a participant's age) did not influence decisions to stop driving. The findings suggest that cognitive decline, regardless of levels of amyloid and tau, is a key factor influencing driving capabilities. As older adults become aware of changes in their cognitive abilities, they may make the decision to stop driving.

As the study progressed, 24 participants stopped driving, 15 died, and 46 developed cognitive impairment. Of those who stopped driving, nine developed a neurologic condition, four had vision problems, eight had other common health issues, and three moved to an assisted living facility.

The study found that among participants with cognitive decline, women were more likely to stop driving than men. While the research team did not dive deeper into gender differences in this project, they emphasized that previous studies on driving and older adults have shown that, compared to men, women were often better aware of declines in their driving skills and tended to plan ahead for driving alternatives.

Limitations of the study included the small number of participants who opted to stop driving; a lack of diversity in the participant population; and insufficient details about medical conditions, such as hearing or vision decline, or medications that can impair driving ability. The researchers hope future studies can dive deeper into why some older drivers with poor cognitive test scores opt for driving cessation while others elect to stay behind the wheel.

This research was supported in part by NIA grants R01AG068183, R01AG067428, R01AG07430, P30 AG066444, P01AG003991, and P01AG026276.

These activities relate to NIH's AD+ADRD Research Implementation Milestone 9.H, "Biomarkers: Early detection measures."

Reference: Babulal GM, et al. Predicting driving cessation among cognitively normal older drivers: The role of Alzheimer disease biomarkers and clinical assessments. Neurology. 2024. Epub April 15. doi:10.1212/WNL.0000000000209426.