Effects of caffeine on the electrophysiological, cognitive and motor responses of the central nervous system

Abstract

Caffeine is the most consumed psychoactive substance in the world. The effects of caffeine have been studied using cognitive and motor measures, quantitative electroencephalography (qEEG) and event-related potentials. However, these methods are not usually employed in combination, a fact that impairs the interpretation of the results. The objective of the present study was to analyze changes in electrophysiological, cognitive and motor variables with the ingestion of caffeine, and to relate central to peripheral responses. For this purpose we recorded event-related potentials and eyes-closed, resting EEG, applied the Stroop test, and measured reaction time. Fifteen volunteers took caffeine (400 mg) or placebo in a randomized, crossover, double-blind design. A significant reduction of alpha absolute power over the entire scalp and of P300 latency at the Fz electrode were observed after caffeine ingestion. These results are consistent with a stimulatory effect of caffeine, although there was no change in the attention (Stroop) test or in reaction time. The qEEG seems to be the most sensitive index of the changes produced by caffeine in the central nervous system since it proved to be capable of detecting changes that were not evident in the tests of cognitive or motor performance.

Radiofrequency signal affects alpha band in resting electroencephalogram

“…It has been reported that caffeine increases alertness and speeds reaction time, dominant factors in relation to alpha power (Fredholm et al 1999;Smith 2002). In addition, previous studies reported a drop in absolute alpha power during rest with eyes open when caffeine was ingested at high doses (Deslandes et al 2005;Siepmann and Kirch 2002). In our study, caffeine assessed in the saliva did not show detectable values (above the device's quantification limit ϭ 2 g/ml), suggesting that caffeinated drinks did not bias the observed results.…”

Effects of Caffeine on Electrophysiological and Neuropsychological Indices after Sleep Deprivation

“…Studies that have combined caffeine ingestion and P300 measures have shown conflicting results. In the current literature there are studies showing no alteration [32] , alterations in just the amplitude [17] , or latency [4] , or both [33] , related or not to an improvement in performance. The variability among subjects may account for such results, since P300 is greatly affected by biological determinants, such as food ingestion, temperature, hours of sleep and the individual's mood [15] .…”

“…Several studies have identified caffeine as a stimulant using motor, behavioral and electrophysiological measures [4][5][6][7][8] . However, other studies failed to demonstrate caffeine effects on cognitive functions, such as attention and memory [9][10][11] .…”

<b>Efeito da ingestão de cafeína sobre o desempenho físico e estado de humor de ciclistas</b> doi: 10.4025/reveducfis.v24i2.16991

“…Estudos recentes têm sugerido que a substância investigada poderia proporcionar um impacto relevante sobre o estado de humor (DUNCAN; OXFORD, 2011;BELL, 2001;RUXTON, 2008;DESLANDES at al., 2005). Entretanto, nenhuma alteração significante foi constatada no presente estudo para os parâmetros de confusão, raiva, depressão, fadiga, tensão e vigor após ingestão de cafeína.…”

“…Alterações da sensação de humor estão atreladas à prática de exercício de alta intensidade e longa duração, em geral, associadas a ambientes quentes e secos (RUXTON, 2008). Da mesma forma, Deslandes et al (2005) não detectaram alterações causadas pela ingestão de cafeína no estado de humor e no desempenho cognitivo, bem como nas áreas cerebrais relacionadas. Ressalta-se que os estudos são inconcluvivos quanto o real efeito cognitivo e de humor associado ao consumo da cafeína (CROWE, 2006;RUXTON, 2008).…”