Research Paper about Caffeine Consumption

From the occasional cup of earl grey tea to the ubiquitous consumption of early-morning lattes, caffeinated beverages comprise the preferred psychostimulant of choice amongst the majority of adult-aged Americans (Drewnoski, 2016; Fulgoni, 2015).  As of 2010, an estimated 89% of the adult United States population ingests caffeinated beverages or food on any given day (Fulgoni, 2015).  Although beverages such as coffee, tea, soda, and energy drinks predominantly represent the primary sources of caffeine for most Americans, dietary supplements, and foods such as chocolate, constitute additional sources of caffeinated comestibles (Drewnoski, 2016; Gurley, 2015).  

Individual motives for caffeine consumption differ; however, commonly reported reasons for the ingestion of caffeine include an expectancy of improvements in areas of cognitive functioning such as concentration and alertness (Ágoston, 2018; Huntley, 2012; Mahoney, 2019).  Considering the overall prevalence of caffeine consumption, alongside frequent expectations that caffeine effectuates enhancement in cognitive functioning, further research examining the specific potential cognitive effects of caffeine consumption is likely a necessary component of improved understanding regarding the cognitive, pharmacological, and biochemical processes underlying caffeine ingestion. 

In regard to pharmacological and biochemical mechanisms, cognitive effects associated with caffeine consumption predominantly result from caffeine antagonizing, or binding with and blocking, adenosine receptors primarily located in the hippocampus and cortex; Caffeine specifically antagonizes adenosine receptors due to the similar chemical compositions of caffeine and adenosine (Diukova, 2012).  Through antagonizing adenosine receptors, caffeine impedes the neuron-to-neuron or nerve cell-to-nerve cell transmission of adenosine, an inhibitory neurotransmitter responsible for a variety of nervous system functions that include suppressing levels of arousal and encouraging sensations of sleepiness (Riberio, 2010). 

Aggregate data from research investigating the specific cognitive effects associated with caffeine consumption suggests that caffeine engenders several well-documented and generally accepted cognitive effects: overall improvements in reaction times, a preclusion of attention and alertness deficiencies particularly resulting from less than optimal levels of arousal, and improved performance on tasks necessitating sustained attention (Giles, 2012; McLellan, 2016; Smith, 2009). However, despite broad consensus regarding the effects of caffeine on reaction times and attention, data from research particularly examining the influence of caffeine on higher-level cognitive processes other than attention indicate mixed results and accentuate a need for further research specifically investigating the effects of caffeine on higher-level cognitive processes (Adan, 2010; Looby, 2021; McLellan, 2016)

Appreciably comprehensive reviews, examining aggregate data gathered from research studies specifically investigating the influence of caffeine consumption on cognitive processes, suggest that the predominant effect of caffeine ingestion on higher-level cognitive processing is an overall enhancement of sustained attention (Einöther, 2013; McLellan, 2016). Relatively recent research specifically employing the Wisconsin Card Sorting Test as a measure for higher-level cognitive processes, however, provides mixed results regarding the efficacy of caffeine as an enhancer of higher-level cognitive processing skills other than attention, such as perseverance, working memory, abstract thinking, cognitive flexibility, and set-shifting (Adan; 2010, Looby, 2021)

In particular, research conducted by Looby and colleagues (2021), produced data indicating that a group of participants who ingested caffeine demonstrated more errors and fewer consecutive runs of correct responses on the Wisconsin Card Sorting Test as compared to groups of participants who did not ingest caffeine. Conversely, data resulting from research conducted by Adan and colleagues (2010) indicated that a group of participants who ingested caffeine exhibited no significant difference in performance on the Wisconsin Card Sorting Test as compared to groups of participants who consumed a placebo. 

Interestingly, however, despite apparently inconsistent results regarding the potential influences of caffeine on higher-level cognitive processing, research participants who consumed caffeine and demonstrated comparatively more overall errors and fewer consecutive runs of correct responses on the Wisconsin Card Sorting Test consumed considerably more caffeine (200 mg) than research participants who demonstrated no significant difference in performance on the Wisconsin Card Sorting Test (75 mg) (Adan, 2010; Looby, 2021). Considering the paucity of previous studies expressly investigating a potential dose-dependent effect of caffeine on higher-level cognitive processes, further research and experimental replication regarding the potential effects of varying amounts of caffeine on higher-level cognitive processes are necessitated.