AGING, CAFFEINE, AND INFORMATION-PROCESSING - AN EVENT-RELATED POTENTIAL ANALYSIS

Structural and energetic processes in information processing were stud ied in young and elderly subjects. A visually focussed selective searc h task was used, in which subjects had to select relevant information, followed by controlled memory search processes to locate a target ite m. Caffeine was used to manipulate the energetic state of the subjects . During task performance event-related potentials (ERPs) and reaction time (RT) were recorded. Subjects were 15 young and 15 elderly health y, non-smoking, moderate caffeine consumers (250-600 mg/day). Before t he experimental sessions they abstained from caffeine for greater than or equal to 12 h. In the experiment subjects received 250 mg caffeine or placebo dissolved in decaffeinated coffee. RT data seem to indicat e that aging effects are at least partly due to a shift in the speed-a ccuracy trade-off. ERP results provide evidence for decreased levels o f energy resources in the elderly. The identification of relevant info rmation and stimulus evaluation processes were delayed in the elderly, suggesting an additional effect of aging on structural processes. Caf feine improved performance and increased the amplitude of the N1, N2b, and P3b, in both young and old subjects. These results suggest that c affeine makes more energy resources available for task performance. Th e effects of aging on P3b latency were counteracted by caffeine. Other caffeine effects did not differ significantly between young and elder ly subjects.