International Journal of Phytomedicine and Phytotherapy
Table 1 Summary of published findings on the effect of Black Tea on cognitive process
From: The effect of black tea on human cognitive performance in a cognitive test battery
Study | Dose | Task type | Positive effect | Negative or No effect |
|---|---|---|---|---|
Caffeine, ERP study [29] | 250 mg | Auditory Go/NoGo | Global increases in P1, P2 and P3b amplitudes to Go stimuli | N1 or N2 (Go stimuli), any components (NoGo stimuli) |
Caffeine, ERP study [16] | 3 mg/kg | Visual search | Subjects reacted faster | Negative ERP deflection was unaffected |
Caffeine [20] | 400 mg | Visual search, Simple choice reaction time | Positive effect depends on the level of caffeine use. | |
Green tea [9] | 1 cup to 6 cups | Mini-Mental State Examination | Higher consumption is associated with a lower prevalence of cognitive impairment | |
Breakfast cereal and caffeinated coffee [22] | Working memory, attention and mood | No effect on initial mood or working memory capacity | ||
Caffeine [21] | Visual information processing | Does not affect cognition, learning & memory performance | ||
Breakfast and caffeine [50] | 4 mg/kg | Free recall and recognition memory and semantic memory | Impaired accuracy | |
Glucose & caffeine, fMRI study [53] | Glucose (75 g) + Caffeine (75 g) | Sustained attention | Increase the efficiency of the attentional system | |
Caffeine [25] | 4 mg/kg | Delayed memory, metamemory and sustained attention | Not affect the magnitude or accuracy of memory predictions | |
Caffeine, fMRI study [54] | 100 mg | WM maintenance task | Detrimental effect on WM at higher levels of WM load | |
Caffeine, fMRI study[17] | 250 or 500 ml | WM | Alters brain activity in DLPFC area | |
Caffeine [55] | 200 mg | ‘N-Back’ WM paradigm | Heightened WM performance | |
Caffeine, Review paper [56] | Does not improve learning and memory | |||
L-theanine, caffeine [26] | L-theanine (250 mg) + caffeine (150 mg) | Simple reaction time, Numeric WM RT and sentence verification | Faster reaction time and improved sentence verification accuracy | |
L-theanine, caffeine [28] | L-theanine (100 mg) | Target discrimination | Increase in hit rate and target discriminability (d’) for the combined treatment | No effects were detected for l-theanine alone |
L-theanine [27] | 200 mg + 100 ml water | Attention test | Improves attention and reaction time response |