The relationship between brain structure and function and driving performance in older adults with and without cognitive impairment: a systematic review

Background: Cognitive deficits in older people are known to affect driving behaviours, however cognitive testing alone does not reliably distinguish safe from unsafe drivers. Research investigating alterations in key brain regions underpinning cognitive performance across cognitive domains may provide crucial additional evidence for fitness-to-drive assessments for older people both with and without cognitive decline. Objective: This review synthesised studies that examined relationships between brain structure, function, and driving performance in older drivers with and without cognitive decline. We aimed to explore how changes in key brain regions that support cognitive performance across various domains may provide additional, critical evidence to improve fitness-to-drive assessments in this population. Data sources: Published studies on Medline, PsycInfo, and Scopus as of October 2023 were examined in this review. Results: Twenty studies were included, 14 for participants without cognitive impairment (CI) and six for participants with CI. Alterations in brain structure and function were differentially related to driving depending on whether or not participants had CI, as well as which driving behaviours were measured. Prefrontal cortical integrity, as well as hippocampal integrity demonstrated the most consistent relationship with driving for older drivers without CI. In those with CI, alterations in frontal, and parietal regions, as well as changes at the whole-brain level were most consistently related to driving performance. Errors emerged as the driving behaviour most consistently related to differences in brain structure and function across both groups. Limitations: This review was limited to English language and peer-reviewed papers which potentially introduced bias. Conclusions: Relationships between brain alterations and driving varied dependent on the presence of CI. Given that the extant literature is sparse, further investigations are warranted to confirm the key brain differences that reliably delineate these cognitive groups. Such findings would be invaluable for enhancing fitness-to-drive assessments for older adults by incorporating more precise neurobiological markers into evaluation protocols. Additionally, this field of study would benefit from the inclusion of other imaging techniques, such as diffusion-weighted imaging (DWI), which offers insights into white matter integrity and microstructural changes that other imaging techniques do not capture. Future investigations should also focus on specific driving behaviours, such as errors, and utilise validated measures for anatomy and driving. Implications: Brain-based data could add reliable cumulative evidence to fitness-to-drive assessments and improve road safety for all road users.