The Effects of Caffeine Withdrawal on Cognitive P300 Auditory and Visual Evoked Potentials

Cagy

et al. 2005

Braz J Med Biol Res

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.

Section: Cognitive and Motor Measuresmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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

Cagy

et al. 2005

Braz J Med Biol Res

“…Depending on the experimental conditions, caffeine ingestion will produce different effects on P300 latency. Reeves et al 19 observed a shortening of P300 latency but no changes in P300 amplitude with 13 caffeine-user subjects, submitted to four days of caffeine-deprivation. Recently, investigators observed hypo- glycemia in normal 26 and diabetic 13 subjects through changes in P300 outcomes.…”

Section: Discussionmentioning

confidence: 96%

“…Caffeine's behavioral effects have been documented in a number of laboratories, as well as improvements on attention, mood and vigor tasks. Moreover, a decrease on reaction time and changes on P300 latency 15,19 and amplitude 18 have been associated with the modulator effects of caffeine. Nevertheless, worldwide labs have presented contradictory results and different experimental procedures.…”

mentioning

confidence: 99%

Effects of caffeine on visual evoked potencial (P300) and neuromotor performance

Cagy

et al. 2004

Arq. Neuro-Psiquiatr.

-The stimulant effects of caffeine on cognitive performance have been widely investigated. The visual evoked potential, specially the P300 component, has been used in studies that explain the stimulant mechanisms of caffeine through neurophysiological methods. In this context, the present study aimed to investigate electrophysiological changes (P300 latency) and modification of cognitive and motor performance produced by caffeine. Fifteen healthy volunteers, 9 women and 6 men (26 ± 5 years, 67 ± 12.5 kg) were submitted three times to the following procedure: electroencefalographic recording, Word Color Stroop Test, and visual discrimination task. Subjects took a gelatin caffeine capsule (400 mg) or a placebo (P1 and P2), in a randomized, crossover, double-blind design. A one-factor ANOVA and Tukey' post hoc test were used to compare dependent variables on the C, P1 and P2 moments. The statistical analyses indicated a non-significant decrease in reaction time, Stroop execution time and latency at Cz on the caffeine moment when compared to the others. Moreover, a non-significant increase in Stroop raw score and latency at Pz could be observed.The only significant result was found at Fz.These findings suggest that the positive tendency of caffeine to improve cognitive performance is probably associated with changes in the frontal cortex, a widely recognized attention area.KEY WORDS: P300, caffeine, neuromotor performance. Efeitos da ingestão de cafeína no potencial evocado visual (p300) e no desempenho neuromotorRESUMO -Os efeitos estimulantes da cafeína no desempenho cognitivo vêm sendo amplamente investigados. O potencial evocado visual (P300) tem sido empregado em estudos recentes que buscam elucidar os mecanismos excitatórios da cafeína através de métodos neurofisiológicos. Neste contexto, o presente estudo objetivou examinar as variações geradas pela cafeína em respostas eletrofisiológicas (latência do P300) e determinar modificações no desempenho cognitivo e motor. Para tanto, 15 indivíduos hígi-dos, sendo 9 mulheres e 6 homens (26 ± 5 anos, 67 ± 12,5 kg) foram submetidos por três vezes à seguinte rotina: aquisição de sinais eletroencefalográficos, Word Color Stroop Test e tarefa de discriminação visual. Foi administrada uma cápsula gelatinosa de 400 mg de cafeína ou de placebo (P1 e P2) em um desenho randomizado duplo-cego cruzado. Foi empregada a ANOVA com um fator e post hoc de Tukey -HSD para a comparação das variáveis nos momentos C, P1 e P2. O momento cafeína apresentou redução não significativa no tempo de reação, no tempo de execução do Stroop e na latência em Cz. Observou-se também aumento não significativo no escore bruto do Stroop e na latência em Pz. O único resultado significativo encontrado foi na latência em Fz.Assim, pode-se concluir que a tendência favorável à ingestão de cafeína na melhora das respostas cognitivas pode estar relacionada a mudanças em regiões específicas do cérebro, como o córtex frontal, área amplamente relacionada com os processos de atenção. PALAVRAS-CHAVE: P300, ...

“…In this context, caffeine can be regarded as a neuromotor modulator. More o v e r, a decrease on reaction time and changes o n P300 latency 11,12 and amplitude 13 have been associated with caff e i n e 's modulatory effects. In a rec e n t s t u d y, a shorter P300 latency and higher amplitude, specifically at Fz, were observed after the administration of caffeine when compared to placebo.…”

Section: Snc) O B J E T I V Omentioning

confidence: 99%

Neuromodulatory effects of caffeine and bromazepam on visual event-related potential (P300): a comparative study

Montenegro

et al. 2005

Arq. Neuro-Psiquiatr.

The P300 component of the event-related potential (ERP) is a general measurement of "cognitive efficiency". It is an index of the ability of an individual's central nervous system (CNS) to process incoming information. OBJECTIVE: To compare the neuromodulatory effects of caffeine and bromazepam on the visual ERP (P300), in relation to a P300 normative database. METHOD: 15 right-handed individuals (7 male and 8 female), between 20 and 30 years of age, healthy, free of any cognitive impairment and not making use of psychoactive substances were studied. Participants were submitted to a visual discrimination task, which employed the "oddball" paradigm, after the administration of caffeine and bromazepam, in a randomized, double-blind design. RESULTS: Statistically significant differences were observed when the caffeine and bromazepam conditions were compared to the normative database. CONCLUSION: The present results suggest that caffeine and bromazepam have distinct modulatory effects on CNS functioning.