Hindmarch I, Quinlan P T, Moore K L, Parkin C
HPRU, University of Surrey, Milford Hospital, Godalming, UK.
Psychopharmacology (Berl). 1998 Oct;139(3):230-8. doi: 10.1007/s002130050709.
Nineteen healthy volunteers ingested 400 ml black tea, coffee, caffeinated water, decaffeinated tea or plain water on three occasions through the day (0900, 1400 and 1900 hours). A 2 x 2 factorial design with caffeine (0, 100 mg) and beverage type (water, tea) was employed, with coffee (100 mg caffeine) as a positive internal control, based on a five-way crossover. A psychometric test battery comprising critical flicker fusion (CFF), choice reaction time (CRT), short-term memory (STM) and subjective sedation (LARS) was performed at regular intervals throughout the day, and intensively so immediately following each beverage. Consumption of tea compared to water was associated with transient improvements in performance (CFF) within 10 min of ingestion and was not affected by the time of day. Caffeine ingestion was associated with a rapid (10 min) and persistent reduction in subjective sedation values (LARS), again independent of time of day, but did not acutely alter CFF threshold. Over the whole day, consumption of tea rather than water, and of caffeinated compared to decaffeinated beverages, largely prevented the steady decline in alertness (LARS) and cognitive capacity observed with water ingestion. The effects of tea and coffee were similar on all measures, except that tea consumption was associated with less variation in CFF over the whole day. No significant treatment effects were apparent in the data for the STM. Tea ingestion is associated with rapid increases in alertness and information processing capacity and tea drinking throughout the day largely prevents the diurnal pattern of performance decrements found with the placebo (no caffeine) condition. It appears that the effects of tea and coffee were not entirely due to caffeine per se; other factors either intrinsic to the beverage (e.g. sensory attributes or the presence of other biologically active substances) or of a psychological nature (e.g. expectancy) are likely to play a significant role in mediating the responses observed in this study.
19名健康志愿者在一天中的三个时段（09:00、14:00和19:00）分别摄入400毫升红茶、咖啡、含咖啡因的水、脱咖啡因茶或白开水。采用2×2析因设计，其中咖啡因含量（0、100毫克）和饮料类型（水、茶）为因素，以咖啡（100毫克咖啡因）作为阳性内部对照，基于五交叉设计。在一天中定期进行包括临界闪烁融合（CFF）、选择反应时（CRT）、短期记忆（STM）和主观镇静（LARS）的心理测量测试组，并且在每次饮用饮料后立即密集进行测试。与饮用白开水相比，饮用茶在摄入后10分钟内与表现（CFF）的短暂改善相关，且不受一天中时间的影响。摄入咖啡因与主观镇静值（LARS）迅速（10分钟）且持续降低相关，同样不受一天中时间的影响，但并未急性改变CFF阈值。在一整天中，饮用茶而非白开水，以及饮用含咖啡因饮料而非脱咖啡因饮料，在很大程度上防止了饮用白开水时观察到的警觉性（LARS）和认知能力的稳步下降。茶和咖啡在所有测量指标上的效果相似，只是饮用茶与一整天中CFF的变化较小相关。在STM的数据中未观察到显著的治疗效果。摄入茶与警觉性和信息处理能力的快速提高相关，并且一整天饮茶在很大程度上防止了在安慰剂（无咖啡因）条件下发现的表现下降的昼夜模式。看来茶和咖啡的效果并非完全归因于咖啡因本身；饮料本身固有的其他因素（如感官特性或其他生物活性物质的存在）或心理性质的因素（如预期）可能在介导本研究中观察到的反应中起重要作用。
