Objectives: This study aimed to examine the effects of green tea extract on working memory in healthy younger (21 - 29 y) and older (50 - 63 y) women.
Design: A single-blind, placebo-controlled, crossover design was used.
Setting: A university laboratory.
Participants: Twenty non-smoking Caucasian women were recruited in the younger (10) and older (10) age group.
Intervention: Subjects received 5.4 g green tea extract (at least 45% epigallocatechin-3-gallate) or placebo (cornstarch) within a 24-hour period.
Measurements: Working memory was measured by reading span and N-back task paradigm. Blood sample (20 mL) was collected and measured for plasma malondialdehyde (MDA) and total antioxidant capacity (TEAC) concentration. A 24-hour recall was conducted for each treatment period to ensure similar dietary patterns.
Results: Green tea extract significantly improved reading span performance in older women, indicated by higher absolute and partial scores of reading span. No significant changes were observed in the younger group. N-back latencies and accuracies were not significantly different after green tea treatment in either age group. Plasma concentration of MDA and TEAC were not different after green tea extract in either group.
Conclusion: Acute supplementation of decaffeinated green tea extract may enhance working memory capacity of women between 50 to 63 years of age. This study provides preliminary evidence that consumption of green tea extract may enhance the cognitive performance in older adults and thus provide potential chemopreventive benefits in this group. The mechanism should be explored in future research.
Keywords: Green tea; N-back task; oxidative stress; reading span; working memory capacity.