Warburton D M, Bersellini E, Sweeney E
Department of Psychology, Earley Gate, Whiteknights Road, Reading RG6 6AL, UK.
Psychopharmacology (Berl). 2001 Nov;158(3):322-8. doi: 10.1007/s002130100884.
Caffeine is present in a wide variety of beverages, often together with a number of other ingredients, such as sugars, taurine, glucuronolactone and vitamins. However, the majority of psychopharmacological studies have used pure caffeine tablets or drinks with doses in excess of those normally consumed in daily life. In addition, all the participants are usually deprived of caffeine for 10 h or more before the study. Consequently, it has been argued that any improvement in performance is only due to a reversal of caffeine withdrawal.
The present two studies tested participants who had minimal deprivation from caffeine (an hour or less) with an 80-mg caffeinated (80 mg/250 ml), taurine-containing beverage (commercially available) verum, which also contained sugars, glucuronolactone and vitamins. The placebos in the two studies were a sugar-free and a sugar-containing drink, in order to examine the effects of the sugar.
In total, 42 participants were tested with a rapid visual information test, a verbal reasoning test, a verbal and non-verbal memory test and a set of mood measures. Prior to testing, they were allowed ad libitum caffeinated beverages until 1 h before testing (study 1) and unrestricted caffeine use before testing (study 2).
In both studies, the caffeinated, taurine-containing beverage produced improved attention and verbal reasoning, in comparison with a sugar-free and the sugar-containing drinks. The improvement with the verum drink was manifested in terms of both the mean number correct and the reaction times. Another important finding was the reduction in the variability of attentional performance between participants. No effects on memory were found. There were no differences in performance between the glucose and sugar-free drinks.
Moderate doses of caffeine and taurine can improve information processing in individuals who could not have been in caffeine withdrawal.
咖啡因存在于各种各样的饮料中，通常还与许多其他成分一起，如糖、牛磺酸、葡萄糖醛酸内酯和维生素。然而，大多数精神药理学研究使用的是纯咖啡因片或剂量超过日常生活中正常摄入量的饮料。此外，在研究前，所有参与者通常要停用咖啡因10小时或更长时间。因此，有人认为，任何表现的改善都仅仅是由于咖啡因戒断反应的逆转。
本两项研究测试了咖啡因戒断时间最短（一小时或更短）的参与者，使用一种含80毫克咖啡因（80毫克/250毫升）、含牛磺酸的饮料（市售）作为真药，该饮料还含有糖、葡萄糖醛酸内酯和维生素。两项研究中的安慰剂分别是无糖饮料和含糖饮料，以检验糖的影响。
共有42名参与者接受了快速视觉信息测试、语言推理测试、语言和非语言记忆测试以及一系列情绪测量。在测试前，研究1允许他们在测试前1小时随意饮用含咖啡因的饮料，研究2则在测试前不受限制地饮用咖啡因。
在两项研究中，与无糖饮料和含糖饮料相比，含咖啡因、牛磺酸的饮料提高了注意力和语言推理能力。真药饮料的改善体现在正确答案的平均数和反应时间上。另一个重要发现是参与者之间注意力表现的变异性降低。未发现对记忆有影响。葡萄糖饮料和无糖饮料在表现上没有差异。
中等剂量的咖啡因和牛磺酸可以改善那些不可能处于咖啡因戒断状态的个体的信息处理能力。
