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Faster but not smarter: Effects of caffeine and caffeine withdrawal on alertness and performance

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Rationale Despite 100 years of psychopharmacological research, the extent to which caffeine consumption benefits human functioning remains unclear. Objectives To measure the effects of overnight caffeine abstinence and caffeine administration as a function of level of habitual caffeine consumption. Methods Medium-high (n = 212) and non-low (n = 157) caffeine consumers completed self-report measures and computer-based tasks before (starting at 10:30 AM) and after double-blind treatment with either caffeine (100 mg, then 150 mg) or placebo. The first treatment was given at 11:15 AM and the second at 12:45 PM, with post-treatment measures repeated twice between 1:45 PM and 3:30 PM. Results Caffeine withdrawal was associated with some detrimental effects at 10:30 AM, and more severe effects, including greater sleepiness, lower mental alertness, and poorer performance on simple reaction time, choice reaction time and recognition memory tasks, later in the afternoon. Caffeine improved these measures in medium-high consumers but, apart from decreasing sleepiness, had little effect on them in non-low consumers. The failure of caffeine to increase mental alertness and improve mental performance in non-low consumers was related to a substantial caffeine-induced increase in anxiety/jitteriness that offset the benefit of decreased sleepiness. Caffeine enhanced physical performance (faster tapping speed and faster simple and choice reaction times) in both medium-high and non-low consumers. Conclusions While caffeine benefits motor performance and tolerance develops to its tendency to increase anxiety/jitteriness, tolerance to its effects on sleepiness means that frequent consumption fails to enhance mental alertness and mental performance.
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... Via the first mechanism (i.e., blocking adenosine receptors), caffeine intake results in an increased release of dopamine, noradrenaline, and glutamate and is thought to positively impact cognition (see Cappelletti et al., 2015, for more information). The cognition-enhancing properties of caffeine have been debated (Einöther & Giesbrecht, 2013;Rogers et al., 2013), and to discuss its mental-enhancing properties it is important to emphasize the importance of habitual caffeine consumption as a personal characteristic that impacts the effectiveness of caffeine (Rogers et al., 2013). Overall, caffeine clearly does enhance motor performance (faster) in caffeine consumers. ...
... Via the first mechanism (i.e., blocking adenosine receptors), caffeine intake results in an increased release of dopamine, noradrenaline, and glutamate and is thought to positively impact cognition (see Cappelletti et al., 2015, for more information). The cognition-enhancing properties of caffeine have been debated (Einöther & Giesbrecht, 2013;Rogers et al., 2013), and to discuss its mental-enhancing properties it is important to emphasize the importance of habitual caffeine consumption as a personal characteristic that impacts the effectiveness of caffeine (Rogers et al., 2013). Overall, caffeine clearly does enhance motor performance (faster) in caffeine consumers. ...
... Overall, caffeine clearly does enhance motor performance (faster) in caffeine consumers. However, it does not appear to improve mental performance (Rogers et al., 2013). In terms of faster reaction times after caffeine intake, follow-up research on the possible role of caffeine to enhance mental performance has been performed (Carswell et al., 2020). ...
... Cognitive enhancing dietary supplements (i.e., nootropics) have been used by esports athletes to gain a competitive advantage and given their increasing popularity among esports athletes, there is a clear need to vet products for safety and efficacy 10 . Caffeine, a methylxanthine, has been shown to improve mental performance (i.e., faster reaction times and motor performance) 11 . Caffeine can be beneficial in enhancing reaction time, vigilance, and attention and may mitigate low levels of awareness and activation during prolonged monotonous activities 12 . ...
... Caffeine has also been shown to enhance the ability to inhibit inappropriate responses (i.e., false alarms when being faced with incompatible stimuli) in habitual users 14 , a function important in video game performance, which often incorporates reactive inhibition. Rodgers et al. 11 showed 150 mg of caffeine enhanced motor speed and simple reaction time during simple computer tasks but did not enhance recognition memory showing that caffeine made them faster not smarter. However, not all studies have found benefits. ...
... In addition, CAFF decreased cognitive control as measured by decreased reaction time to false alarm targets from baseline (i.e., the player became trigger-happy) in the Trigger control task and increased self-reported feelings of jitteriness. These findings parallel Rodgers et al. 11 that caffeine made them faster not smarter and caffeine's tendency to elevate feelings of jitteriness. Results also suggest that Dynamine™ and TeaCrine® may add a potential benefit when added to a caffeinated supplement due to a dampening effect on caffeine's positive effects on speed and reaction time while combating the negative effects of caffeine (decreased cognitive abilities & performance reliability, increased jitteriness). ...
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Purpose: To compare the effects of purported cognitive enhancing dietary bioactive ingredients on subjective and objective measures of cognitive and motor performance during a first-person shooter video game.Methods: Using a placebo-controlled crossover design, nine healthy men (23.4±5.7 yr, 178.9±5.8cm, 86.0±17.1kg) completed four 20-minute gaming sessions designed to assess cognitive, motor, and perceptual skills via artificial intelligence-driven battery of tasks (Aim Lab). Participants ingested either a placebo (PL), caffeine (CAFF), or caffeine + methylliberine (Dynamine™) + theacrine (TeaCrine®) (CMT). Before and after each gaming session participants rated various feelings of affect. Data were analyzed using mixed factorial ANOVA, bootstrapping post-hoc tests with 95% confidence intervals, and effect sizes.Results: Compared to PL, self-assessed performance was significantly increased in CMT vs. PL (p=0.035) and self-assessed jitteriness was increased by CAFF vs. PL (p=0.043). CMT was associated with a greater improvement of participants’ visuo-spatial working memory from baseline vs. PL (p=0.04) and CAFF (p=0.033). CAFF had a greater decrease in reaction time for false alarms (indicating diminished cognitive control) from baseline vs. PL (p=0.002) and CMT (p=0.001) and a greater increase for time on target tracking vs. PL (p=0.008) and CMT (p=0.047). Compared to PL, CMT was associated with a greater decrease in median kill time (indicating improved speed) (p=0.017). Compared to PL, systolic blood pressure was significantly increased by CAFF (p=0.025) and CMT (p=0.020) but remained within normal limits.Conclusions: Acute CMT supplementation improved cognitive and motor abilities in recreational gamers. The addition of theacrine and methylliberine to caffeine may lessen some undesirable effects of isolated caffeine ingestion on cognitive control and jitteriness.
... Acute caffeine-induced improvements in attention are found in simple and choice RT tasks [39][40][41]42], RVIP tasks [41,43,44,452 ], and visual search tasks [46], but not in cueing tasks [47]. It must be noted that some of these positive caffeine effects may be attributed to a reversal of the negative consequences of caffeine withdrawal [48]. Improvements in spatial, verbal, and numeric working memory tasks have been reported [41,44], [2,45 ], but not consistently so [39]. ...
... Furthermore, it might be advisable to target specific groups that perform at a lower baseline level than our healthy young university students did, such as elderly, fatigued, or sleep-deprived individuals. Finally, we did not strictly control the (habitual) intake of flavanols and caffeine, which would also be advisable to assess possible contributions of withdrawal effects, which has been a concern in the caffeine literature in particular (e.g., [48],but see also [72]). ...
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Purpose Consumption of cocoa flavanols and caffeine might acutely enhance cognition, particularly in synergy. Due to the use of multifaceted tasks in prior research, it is unclear precisely which cognitive functions are implicated. Here we aimed to assess the acute effects of the (joint) ingestion of cocoa flavanols and caffeine on temporal attention, spatial attention, and working memory. Methods In four separate sessions of a randomized, double-blind, placebo-controlled, crossover trial, 48 young adult participants consumed a placebo drink, a cocoa flavanols (415 mg) drink, a caffeine (215 mg) drink, and a drink containing both concurrently. In each session, after ingestion, we tested performance in three cognitive tasks. We tested temporal attention in a dual-target rapid serial visual presentation paradigm, known to elicit the attentional blink, in which the time between the targets was manipulated. We measured spatial attention in a visual search task, where we varied the number of distractors that appeared simultaneously with the target. We tested working memory in a delayed recall task, in which the number of stimuli to be remembered was manipulated. Results We obtained the expected performance pattern in each task, but found no evidence for modulation of response accuracy or reaction times by the ingestion of either substance, nor of their combined ingestion, even in the most challenging task conditions. Conclusions We conclude that, even when jointly ingested, neither the tested amount of cocoa flavanols nor caffeine have acute effects that are robustly measurable on cognitive tasks that target attention and working memory specifically.
... A second concern is the paper's overly simplistic conceptualization of the relationship between alertness, error, task performance, and implied safety. While there is little doubt that reduced alertness can sometimes underpin threats to performance and safety [9], pharmacologically reversed sleepiness can also lead to errors, performance decrements, and reduced safety [10]. Moreover, there is evidence to suggest that reduced alertness may not always lead to increased errors. ...
... This finding aligns with previous research demonstrating improved hit time (average time needed to hit a target) following an acute 3 mg·kg −1 BM dose of caffeine in a similar shooting task (33). Such improvements may be attributed to an increase in motor speed that is typically seen following caffeine administration (44). However, contradictory findings have reported no significant differences in hit rate (hits/ sec) with a 200 mg dose of caffeine compared to a placebo (31), and no significant difference in time to eliminate targets with a 150 mg dose of caffeine compared to placebo (32). ...
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... Recent studies suggest that regular moderate caffeine consumers generally experience a lessened effect on reaction time and/or cognitive performance when compared to regularly high caffeine consumers (Attwood et al., 2021;Rogers et al., 2013). Many differences have been seen in caffeine studies examining reaction time in various populations and the differences have been attributed to regular usage, dosages, and whether the subjects had recently ingested caffeine (Lane, 1997;Nehlig, 2010;Lieberman et al., 2010;Einother & Giesbrecht, 2013). ...
... Adverse effects of caffeine are either consequences of excessive amount of the substance consumed or withdrawal from caffeine. These effects usually include prolonged headache, heart rhythm irregularities, insomnia, and increase in anxiety and jitteriness (108,109). Green tea is rich in flavonoids such as catechin. It was previously suggested that catechins could regulate blood pressure by protecting vascular endothelial cells and improving vascular integrity (110). ...
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... Prior to beginning each session, participants completed a pre-session questionnaire to record several lifestyle factors that could influence task performance, including sex assigned at birth (male or female), age, caffeine intake, and amount of sleep in the 24 h prior to the testing session (Knufinke et al., 2018;Rogers et al., 2013;Sadler et al., 2022). Participants next completed pre-test assessments, which included an estimation of subjective fatigue level as well as simple reaction time (RT) and inspection time (IT) tasks (described in Section 2.4 "Pre-and Post-Tests"). ...
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Men and women (n = 54) aged between 18 and 82 years completed a questionnaire designed to elicit information on their past and present coffee and tea drinking habits. Tea was first drunk regularly (≥ once a week) at a younger age than coffee (9.2 vs. 12.8 years, p<0.001). Both drinks were consumed initially with more sugar (p<0.001) and more milk (p = 0.04) added. Among the benefits significantly (p<0.05) associated with consuming tea and coffee were increased feelings of relaxation and calmness, and decreased drowsiness. Drinking coffee was perceived to increase clearheadedness, while tea (but not coffee) was perceived to reduce thirst. This study is a preliminary attempt to investigate the various factors contributing to the acquisition of liking for coffee and tea. The results indicate an important role for mood changes associated with the consumption of these drinks. It is likely that only some of these effects are due to caffeine; moreover, it appears that relatively few of the actual psychoactive effects of caffeine are recognised by consumers.
Chapter
Caffeine is widely consumed and has widespread physiological effects. We review evidence that the acute alerting and associated psychomotor performance effects of caffeine experienced by frequent caffeine consumers represent withdrawal reversal rather than a net benefit for functioning, and that avoidance of withdrawal is an important motive for caffeine consumption. On the other hand, tolerance develops to the anxiogenic effect of caffeine even in susceptible individuals, and while caffeine raises blood pressure, tea and coffee consumption are not associated with increased risk of vascular disease. Indeed, consumption of these drinks appears to reduce risk of cognitive decline in older age, possibly because of beneficial actions of other compounds present in tea and coffee, and the sensitization of the neuroprotective action of adenosine resulting from caffeine intake. The example of caffeine demonstrates the challenge of finding ingredients for foods or drinks that could be used effectively to acutely enhance mood, alertness and/or cognitive function.