Effect of matcha green tea on cognitive functions and sleep quality in older adults with cognitive decline: A randomized controlled study over 12 months.

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• Dementia pathophysiology is believed to develop in middle age (approximately 45–54 years-old). Nutritional support that focuses on maintenance of cognitive function should therefore be considered when presented with a patient in this age range even when no cognitive impairment symptomatology presents.
• Sleep support is fundamental given its association with cognitive decline; early intervention and maintenance of good sleep patterns are therefore crucial at any age.
• Signs of facial emotion recognition impairment might be indicative of early stage mild cognitive impairment (MCI) and subjective cognitive decline (SCD). Nutritional support in terms of anti-inflammatory and anti-oxidant nutrients should therefore be part of an intervention dietary strategy in patients presenting with these symptoms.

Introduction

Aged-related dementia is a growing global concern with the number of affected patients projected to increase from 57.4 million in 2019 to 152.8 million by 2050. Disease progression is insidious and gradual and, as of yet, no effective treatment or indeed conclusive preventative strategy has been identified. Specific nutritional components of matcha green tea are believed to benefit cognitive function by means of antioxidant and anti-inflammatory properties.

Methods

A 12-month randomised, double-blind, placebo-controlled clinical trial assessed the potential of matcha in improving sleep quality and delaying cognitive decline in 99 community-dwelling older adults aged 60–85 years (89 patients completed the trial). Age, sex, and APOE genotype were adjusted for. The participants (n=49) consumed nine capsules of matcha (equivalent to 2 g of matcha) or placebo (n=50) daily at any time. Data collection included standardised cognitive function tests, Pittsburgh sleep quality index scores (PSQI), PET scans for 24 participants (9 male and 15 female), serum, and immunoassay of plasma Aβ1–40 and Aβ1–42 levels.

Results

There were no differences in baseline scores between the two cohorts. After 12-months of intervention a difference of 0.86 (95% CI; -0.002, 1.71) (P = 0.088) in PSQI scores were observed indicating an improvement in sleep quality for the matcha cohort. Significant improvements in social acuity in the neurocognitive domain was furthermore observed (difference; -1.39, 95%CI; -2.78, 0.002) (P = 0.028). There were no observable differences between the cohorts for the other cognitive tests or PET scans.

Conclusion

Even though matcha consumption has no direct impact on the development of dementia, the authors indicate it is a plausible lifestyle improvement strategy that has the potential to improve sleep quality and social acuity that are believed to play a role in the development of late-onset dementia.

• Matcha green tea powder contains epigallocatechin gallate (anti-oxidant and anti-inflammatory polyphenols) and theanine, an amino acid that is believed to alleviate stress and improve sleep quality.
• The daily intake quantity of matcha was set at 2 g in this study because the amount of matcha in the traditional Japanese tea ceremony, Tea Otemae, is 2 g.
• Matcha tea is therefore an affordable and easily implemented nutritional strategy to improve sleep quality and enhance social perception by providing specific dietary micronutrients for adults of any age.

• Larger scale studies targeted at a more diverse cultural cohort are needed to support the outcome of this study.
• Matcha tea is part of Japanese culture and the efficacy of intake in other cultures are needed to establish quantity reference guidelines.
• The specific effects of matcha tea intake on dementia and Alzheimer biomarkers need further investigation.