0114 Morning Stimulant Administration Reduces Sleep and Overnight Working Memory Improvement

Abstract

Introduction The goal of cognitive enhancement is to improve mental functions using interventions including cognitive training, brain stimulation and pharmacology. Indeed, psychostimulants, commonly used for cognitive enhancement purposes, while preventing sleep, have been shown to increase working memory (WM) and attention. WM is widely believed play a core role in cognitive ability, and has been shown to correlate with broad measure of cognitive ability and fluid intelligence. Sleep, however, is also important for cognitive function; thus, understanding the interaction between stimulants, sleep and cognition may inform current approaches to cognitive enhancement. Methods We used a double-blind, placebo controlled, repeated-measure design to investigate the effect of morning administration (9am) of stimulant, dextroamphetamine (DEX, 20 mg), on within-day and overnight WM performance, and sleep in 46 (22 female) healthy young adults. We tested WM using an operation span task (OSPAN) as it engages and captures both the memory retention and online processing capacity of WM. WM was tested at 75 minutes post drug, 12 h post drug, and 24 h post drug over a night of sleep. Results Compared with placebo, DEX showed no changes to WM performance at 75min or 12-hr post-drug. After sleep, DEX performed worse than PBO and the overnight improvement in performance in the PBO condition was absent in the DEX condition. Moreover, sleep quality was negatively affected by DEX administration. Conclusion In summary, we found no cognitive boost from psychostimulants across a day of wake and a blockade of overnight WM increases with the stimulant, compared to PBO. Given the growing non-medical use of stimulants in young adults, these findings have important implications for assessing their benefit for cognitive enhancement. Support Office of Naval Research N00014-14-1-0513 (S.M.) and DoD Young Investigator Prize (S.M.)