Research & Your Health is a series of articles written in accessible, everyday language, focused on the latest scientific research of natural health products.
On May 6, 2016
Background: The vast majority of the world consumes caffeine, a stimulant that activates the sympathetic nervous system (SNS). Previous research has suggested that caffeine consumption enhances one’s attentional abilities. However, less is known about the effects of caffeine on more cognitively complex tasks (called ‘executive functions’), such as updating (altering working memory), shifting (task alternation), inhibition (prevention of performing a dominant response), dual task performance (simultaneous response), planning (organizing and executing to achieve a goal), and access to long-term memory. In addition, most caffeine studies do not take into consideration participants’ habitual caffeine usage (which means the same dosage of caffeine could affect two people quite differently). Furthermore, it is unclear whether the interaction between food and caffeine is important in the performance of cognitive tasks.
Objective: The aim of this study was to examine the effects of personalized habitual caffeine and food intake on attention, executive function, SNS activation, arousal, and mood in young males.
Methods: 58 males (aged 19 to 35) with similar educational backgrounds and caffeine consumption habits participated in this randomized, placebo-controlled study. Each participant was asked to fast overnight before the study began at 8 a.m., and was randomly assigned to one of the following conditions: placebo pill with no breakfast, caffeine pill with no breakfast, placebo pill with breakfast, and caffeine pill with breakfast. The breakfast in this study consisted of a granola bar, and the caffeine dosage corresponded to participants’ self-reported use. Baseline and post-treatment physiological tests were taken, along with post-treatment measures of mood, attention, inhibition, updating, shifting, dual task performance, access to long-term memory, and planning.
Results: Personalized caffeine consumption had positive effects on ratings of fatigue, attentional abilities, and updating. Surprisingly, meal consumption did not change the effects of caffeine consumption on the outcomes of interest. Caffeine did not positively affect mood, inhibition, shifting, dual task performance, access to long-term memory, or planning.
Conclusion: Positive psychological effects of personalized habitual caffeine consumption can be detected in young, healthy, rested males at breakfast time, regardless of whether food is consumed simultaneously or not.
Findings and Perspectives: This study demonstrates that habitual caffeine use can decrease perceptions of fatigue, and increase certain cognitive functions such as attention and updating. However, other executive functions were not positively affected by caffeine consumption. Future studies could similarly explore the effect of habitual caffeine usage in different populations (i.e., females or older adults) during different times of the day.
Lanini, J., Galduróz, J. C. F., & Pompéia, S. Human Psychopharmacology: Clinical and Experimental (2016), 31:1