Effects of acute alcohol and driving complexity in older and younger adults

Rationale: Our previous work demonstrated differential neurobehavioral effects of low-dose alcohol consumption on older and younger adults in a driving simulator. However, the ability to enhance or suppress a response in such context has yet to be examined. Objectives: The current study contrasted older and younger drivers’ responses to specific stimuli (i.e., relevant, irrelevant) in scenarios of differing complexity following low-dose acute alcohol administration. Methods: Healthy older (55–70) and younger (25–35) adults completed two driving scenarios (i.e., country and metropolis) both before and after consuming beverages targeted to reach peak BrACs of 0.00, 0.04, or 0.065%. Throughout the simulation, participants encountered relevant stimuli (e.g., pedestrians walking into the street) and irrelevant stimuli (e.g., pedestrians walking parallel). Peak deceleration, range of steering, and distance until brake application were assessed within a 450-ft window preceding each stimulus. Results: Following low-dose alcohol consumption, older adults shifted from a strategy using both deceleration and steering to relying solely on deceleration in responding to relevant stimuli in the country. Older adults under both low and moderate alcohol conditions displayed an inability to withhold responses to irrelevant stimuli in the metropolis. Conclusion: These findings are consistent with our prior work showing differential effects of low-dose alcohol on older, relative to younger, adults. The interactive effects of age and alcohol, however, depend on stimulus type and environmental complexity. Continued investigation of neurobehavioral mechanisms in ecologically valid paradigms is necessary for understanding the implications of the combined impairing effects of alcohol and older age.