Abstract

EFFECTS OF REGULAR CAFFEINE CONSUMPTION ON SEMANTIC MEMORY AND CENTRAL EXECUTIVE FUNCTION: A SECONDARY ANALYSIS

Dominic P. Nguyen-Van-Tam, PhD and Andrew P. Smith, PhD*

Abstract

Background: Research has examined the acute effects of caffeine on many aspects of memory. Less is known about the effects of the level of caffeine regularly consumed or how this might interact with the acute effects of caffeine, and this was examined using semantic processing and executive function (logical reasoning) tasks. Methods: A secondary analysis of data from three recently published studies is reported. There were 177 participants (university students) in the dataset. Chronic caffeine consumption was analysed in two ways. The first split the samples into quartiles. The second method compared those who consumed less than 30mg of caffeine daily with those with higher consumption levels. After baseline testing, separate groups either received caffeine or a placebo. The caffeine dose was 4mg/kg and was carried out double-blind. Results: At baseline, there were no significant effects of regular levels of caffeine consumption. The usual positive effects of acute caffeine were observed in both the semantic processing and logical reasoning tasks. No significant interactions existed between regular caffeine intake and caffeine/placebo groups. Conclusion: The results show little effect of the regular level of caffeine consumption and no interactions between this and acute challenge conditions. In contrast, acute effects of caffeine were observed for both tasks, confirming previous findings.

Keywords: Caffeine; Habitual caffeine consumption; Memory; Semantic processing; Executive functioning; Logical reasoning.