The effect of caffeine on cognitive performance and brain activity following a ‘real life’ workday - an fMRI title.

This study aims to determine the effects of acute coffee consumption compared to consumption of decaffeinated coffee on subjective fatigue and vitality ratings, neuropsychological performance and brain activity during working memory and learning tasks. Acute effects will be investigated following a ‘real life’ workday during which caffeine was consumed according to the participant’s habitual regime.

The stimulant effects of caffeine result in its common consumption by individuals in an attempt to combat the detrimental effects of fatigue on performance. However, inconsistent findings regarding the effects of caffeine on cognitive performance mean that the actions of caffeine on cognition are unclear. Further, very few studies have examined brain activity underlying caffeine induced behavioural effects. The present study will use functional magnetic resonance imaging (fMRI) to investigate the effects of acute caffeine consumption in the ‘real life’ context of habitual caffeine use on the brain activity of individuals fatigued by a ‘real life’ workday. Findings will shed light on the mechanisms whereby caffeine affects behaviour and alleviates fatigue.
The study also has a much broader research aim to investigate the use of fMRI as a more sensitive tool for the detection of the effects of nutritional interventions. Functional MRI has already been demonstrated to be a more sensitive method for the detection of subtle cognitive impairment following mild traumatic brain injury, multiple sclerosis, human immunodeficiency virus and chronic fatigue syndrome. The use of fMRI provided validation of cognitive complaints in these groups where assessment using neuropsychological tasks could not. Similarly, it is hoped that fMRI will be able to provide validation of the subjective fatigue alleviating effects of nutritional interventions by demonstrating cognitive task related changes in brain activation.

1. Training session (fatigue assessment scale, need for recovery scale, neurovegetative scale, Dutch adult reading test);

2. 1st testing session (groningen sleep quality scale, karolinksa sleepiness scale, profile of mood state [fatigue and vitality subscales], NASA task load index, finger precueing task, short mackworth clock, letter-digit substitution test, stroop, Scanning tasks [sternberg working memory task, verbal learning task], saliva samples, blood glucose measurement);

3. 2nd testing session (1 week after 1st session: same tasks as 1st session).

All participants will be tested twice: once after acute caffeinated coffee administration (100 mg caffeine, equivalent to 1 cup of coffee) and once after acute decaffeinated coffee administration (placebo).