Naturalistic Driving Outcomes and Sensorimotor Function in Cognitively Normal Older Adults.

BACKGROUND

Driving supports independence and quality of life in later life but is vulnerable to age-related and/or disease-related decline. While cognitive impairment is a well-recognized risk for unsafe mobility, the contribution of sensorimotor function is less understood.

METHODS

We studied 374 cognitively normal older adults (Clinical Dementia Rating = 0 at baseline) enrolled in the DRIVES Project. A SensoryMotor Impairment Index (SMI) was constructed from six domains (grip strength, gait speed, reaction time, hearing, vision, olfaction) and categorized as 0, 1, 2, or ≥ 3 impairments. Naturalistic driving was continuously monitored using in-vehicle GPS dataloggers between 2019 and 2025. Linear mixed-effects models tested whether longitudinal driving trajectories differed by baseline SMI, adjusting for age, sex, race, education, body mass index, and cognition (Preclinical Alzheimer's Cognitive Composite).

RESULTS

At baseline, participants with higher SMI burden were older and had lower cognitive scores (both p < 0.01). Over time, greater sensorymotor impairment was associated with faster declines in driving exposure and spatial range. Compared with SMI = 0, participants with SMI ≥ 3 showed steeper reductions in nighttime trips (-0.050 vs. -0.037 trips/month), long-distance trips (> 20 miles; p < 0.001), and maximum trip distance (p = 0.009), and greater contraction of driving space (entropy and radius of gyration; p < 0.001). Self-reported driving behaviors showed that participants with higher SMI drove fewer days per-week and were more likely to avoid night driving (p < 0.01). Rates of self-reported adverse driving events (e.g., crashes or citations) did not differ significantly across SMI groups, consistent with compensatory self-regulatory behaviors.

CONCLUSION

Greater sensorymotor impairment predicts accelerated decline in naturalistic driving among cognitively normal older adults, independent of cognition. A composite SMI may provide a feasible, low-cost approach to identify older drivers at risk for declining mobility and support timely interventions to prolong safe driving.