title: Caffeine reduces time-of-day effects on memory performance in older adults.
abstract: For most older adults, memory performance depends on the time of day, with performance being optimal early in the morning and declining during the late afternoon hours. In the present study, we asked whether this decline could be ameliorated by a simple stimulant, caffeine. Adults over the age of 65 who considered themselves "morning types" were tested twice over an interval of 5 to 11 days, once in the morning and once in the late afternoon. Participants ingested either coffee with caffeine or decaffeinated coffee at both sessions. Participants who ingested decaffeinated coffee showed a significant decline in memory performance from morning to afternoon. In contrast, those who ingested caffeine showed no decline in performance from morning to afternoon. The results suggest that time-of-day effects may be mediated by nonspecific changes in level of arousal.
authors.affiliation: Department of Psychology, University of Arizona, Tucson 85721-0068, USA. ryant@u.arizona.edu
authors.forename: Lee
authors.initials: L
authors.lastname: Ryan
authors.forename: Colleen
authors.initials: C
authors.lastname: Hatfield
authors.forename: Melissa
authors.initials: M
authors.lastname: Hofstetter
mesh_terms: D000367:Age Factors; D000368:Aged; D002110:Caffeine / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000187:drug effects*; D011897:Random Allocation; D013997:Time Factors
chemical_list: D000697:Central Nervous System Stimulants; D002110:Caffeine