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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