Turns and downturns in aging drivers.

As cognitive decline progresses, older adults may self-regulate their driving. Avoidance of left turns across traffic is observable in naturalistic driving data but rarely self-reported. We studied 106 older adults using baseline and one-year follow-up neuropsychological assessments. In-vehicle sensors passively recorded driving behavior over 12 weeks. We identified 216,531 turns from vehicle heading changes. We used mixed-effects logistic regression to model the odds of turning left, with cognitive status category change from baseline to one-year follow-up as the predictor. Greater cognitive impairment, represented by movement to a more severe cognitive status category at one-year follow-up, was associated with reduced odds of turning left (odds ratio = 0.98, 95 % confidence interval = (0.964, 0.996); P value = 0.011). Left-turn avoidance may be a behavioral marker of early cognitive decline. Passive driving data could help detect functional changes earlier, enabling intervention to preserve mobility and independence.