薬理と治療

Abstract

Objectives　The increase in dementia-related diseases such as Alzheimerʼs has become a growing social problem in recent years. Because there are no fundamental methods of treating these diseases once they occur, expectations are being placed on prevention, using foods that people can consume in their daily lives. Epidemiology researchers have reported that individuals who frequently drink green tea show fewer instances of cognitive function disorders; therefore, green tea is expected to have the effect of preventing dementia-related diseases. This study targeted 62 Japanese men and women, aged between 50 and 69 years, who were aware of a decline in their cognitive function. We asked them to drink 2 g of powdered green tea every day for 12 consecutive weeks, and investigated its effects on their cognitive function. Methods　To examine the subjectsʼ cognitive function, we used the Cognitrax Test（based on the CNS Vital Signs test battery）, of which we performed the following ten tests: Verbal Memory, Visual Memory, Finger Tapping, Symbol Digital Coding, Stroop, Shifting Attention, Continuous Performance, Perception of Emotion, Reasoning, and Four-Part Continuous Performance. The subjectsʼ performances were measured before they started drinking the matcha, and again at 4, 8, and 12 weeks after intake. The subjects completed the MMSE-J before the study began, and those with low scores were selected（starting with 22 points as the lowest score）. Results　Subjects in the matcha group showed a significant decrease（P＜0.05）in the time needed to respond with a correct answer in the Stroop, Shifting Attention, and Four-Part Continuous Performance Tests（Parts 1, 2, and 3）. The number of correct answers for the Shifting Attention Test was also significantly higher（P＜0.05）in matcha group compared with placebo group. However, the intake of matcha had no influence on other test items. Conclusion　Matcha contains theanine and caffeine, which are known to impact the accuracy of attention function, or alertness. Our study also revealed improved reaction time in simple tasks and a greater number of correct answers given in the Shifting Attention Test. Matcha was therefore shown to effectively improve cognitive function, even in middle-aged and older subjects who were aware of a decline in their cognitive function. （UMIN Clinical Trials Registry ID：UMIN000029142）