The effect of black tea on human cognitive performance in a cognitive test battery

Abstract

Abstract Background Black Tea is a widely consumed drink in the world. Evidence suggest Black Tea has stimulatory effect on humans. We investigated the effect of Black Tea on cognition using a cognitive test battery. Methods Participants (n = 32) were fasted overnight for 10 h and restrained from caffeine and other stimulant drugs for 14 days prior to participation. We randomly assigned participants into either an experimental (n = 16) or a control (n = 16) group. Experimental group consumed 250 ml of Black Tea (BT) while control group was received equal volume of water (W). Participants were tested on the following cognitive tasks: executive function, sustained attention, memory (memory span, immediate, delayed, working memory) and arithmetic calculation task. Results We found that BT group performed significantly (p < 0.05) faster in the executive function task (BT: M = 1671, SD = 319; W: M = 1935, SD = 372); simple reaction time task (BT: M = 333, SD = 87; W: M = 361, SD = 101), identification of target location in the visual search task (BT: M = 925, SD = 50; W: M = 972, SD = 115). We also showed that BT group forgotten significantly (p < 0.05) lower number of words in the delayed memory recall test (BT: M = 1.12, SD = 0.15; W: M = 1.37, SD = 0.33) and made significantly (p < 0.05) fewer errors in the trail making task (BT: M = 0.31, SD = 1.01; W: M = 1.31, SD = 1.66). Conclusions BT consumption speeded the performance, improved memory, reduced number of errors in the various cognitive tasks. Our results further showed that even in small volume of BT consumption can speed up cognitive processing.

Keywords

• Attention
• Memory
• Reaction time
• Cognition
• Visual search