Objective: We explored driving patterns under conditions with and without driver distraction in a community sample of adults. Method: We recruited 100 community-dwelling participants who were current drivers (65 men, healthy: n = 52, mild cognitive impairment [MCI]: n = 22, Alzheimer's disease [AD]: n = 8, Parkinson's disease [PD]: n = 11, other: n = 7). Participants drove in a simulator under four rural driving conditions: low vs. high speed and with vs. without distraction (conversation). Driving variables included: lateral position of vehicle from the right road border (m), average speed (km/h), and average time to collision with vehicle ahead (sec). Results: Repeated measures ANCOVAs (covariate: age) showed a group distraction interaction in the high speed condition on average speed, F(3, 74) = 4.251, p = .008, η2 = .147, and time to collision, F(3, 74) = 4.280, p = .008, η2 = .148; the AD group adjusted driving speed and distance given distraction. The only group distraction interaction in the low speed condition was on time to collision, F(3, 70) = 3.656, p = .016, η2 = .135; AD and MCI groups demonstrated more time to collision than PD and control groups. A group main effect on average speed in the low speed condition indicated that all groups but controls decreased speed in the distraction, relative to the no distraction simulation. Conclusion(s): Healthy and MCI groups drove consistently despite distraction factors, while those with AD compensated by driving more slowly and further away from the preceding vehicle. Individuals with PD reacted in counterintuitive ways.