Caffeine Consumption CNSequences: An EEG study on the psychostimulant effects of caffeine on cognitive function in middle to late adolescents

By Tiara Safaei and Natalie Leong
Senior Category (Grades 11-12)
Experiment | Biology, Statistics

BCVSF Note: The required ethics forms have been submitted for this project.

In Canada, caffeine consumption is becoming increasingly prevalent among the middle to late adolescent age group (which, for the purposes of this study, is defined as 16-19 years of age). With an average of 11.1% of the teenage population consuming coffee on a daily basis in 2004 versus 35.9% in 2015, Statistics Canada reports a significant increase in the adolescent consumption of coffee, one of many popular caffeinated beverages. However, a Health Canada study reveals that young people generally have low levels of knowledge regarding caffeine intake and the resulting effects. Since youth caffeine consumption has increased rapidly since the trend’s recent emergence, there is currently very minimal published research into the effects of caffeine that focuses specifically on this age group.

A psychoactive drug, caffeine’s mechanism of action on the central nervous system (CNS) works as an adenosine receptor antagonist. In negating the activity of adenosine, a neurotransmitter whose functions are related to increased tiredness and depressant activity, caffeine increases awakeness and acts as an antidepressant. As such, many students rely on caffeine to perform at school. In spite of popular belief, there is little evidence indicating caffeine improves memory performance. This study, therefore, aims to further society’s knowledge by both informing adolescents regarding caffeine intake and determining the effects of caffeine on the neurological function of the working memory in adolescents. By analyzing adolescent brainwave activity in relation to caffeine consumption, the influence of caffeine on consciousness and cognitive efficiency can be observed.

To determine the impact of caffeine on working memory, a single-blind randomized block design study was planned to be performed with a stratified sample of teenagers in Greater Vancouver. The active treatment group (n=10) would receive a 100mg caffeine pill, and the placebo treatment group (n=10) would receive a sugar pill. After receiving treatment, baseline brain activity was recorded for each participant. Participants then would complete an n-back (2-back) test through a Presentation® coded program using the Neurobehavioral Systems software. Throughout the experimentation, data would be gathered using a 8-channel Neuroelectrics electroencephalogram (EEG). This data would then be filtered with SciPy to focus on filtered points of stimulation, where participants were stimulated by the n-back test and thus used their working memory. To account for individual variation, the local maximum brain activity around the point of stimulation would be calculated for each electrode and combined in a global field power calculation. Once the EEG data had been filtered, the difference between global field powers (stimulation – baseline) for each participant would be calculated.

A two-sample statistical t-test at alpha-level 0.001 was planned to compare the active treatment group versus the placebo treatment group. If the calculated p-level is greater than the alpha-level, the null hypothesis will be rejected, finding convincing evidence that brain activity increases with caffeine treatment. The scope of inference for this designed study applies to the cause and effect of caffeine to the sampled population; therefore, rejecting the null hypothesis would indicate that, to a 99.99% confidence level, caffeine increases cognitive functioning in middle to late adolescents.

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