Table 1. Characteristics of studies included in the review.
| Author | Year | Data source | Sample size | No. of dementia | Follow up time |
Baseline age (years) |
Diagnosis of dementia | Outcomes | Confounders adjusted | Tea type | Main findings | NOS score |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Hu et al. (2022) | 2022 | UK Biobank | 377,592 | 5,122 | 9 years | 58.49 ± 6.83 | ICD-9 and ICD-10 | All caused dementia, AD, VD | Age, sex, ethnicity, TDI, education, BMI, typical sleep duration, smoking status, alcohol status, total consumption of vegetables, total consumption of fruit, total consumption of fish and APOE4 status | Black tea Green tea |
A U-shaped association between tea consumption and dementia risk, and the consumption of around three cups per day showed the strongest protective effect | 9 |
| Schaefer et al. (2022) | 2022 | UK Biobank | 351,436 | 4,270 | 12 years | 38 ~ 73 | ICD-10 | All caused dementia | Age, body fat | Black tea Green tea |
Moderate-to-high tea intake was negatively associated with incident dementia | 6 |
| Zhang et al. (2021) | 2021 | UK Biobank | 365,682 | 5,079 | 11.4 years | 50 ~ 74 | ICD-10 | All caused dementia, AD, VD | Sex, age, ethnicity, qualification, income, BMI, physical activity, alcohol status, smoking status, diet pattern, consumption of sugar-sweetened beverages, HDL, LDL, history of cancer/diabetes/ CAD/hypertension |
Black tea Green tea |
Intake of coffee alone or in combination with tea was associated with lower risk of poststroke dementia | 8 |
| Matsushita et al. (2021) | 2021 | Japan | 13,757 | 309 | 8 years | 40 ~ 74 | / | All caused dementia | BMI, physical activity, energy, smoking, drinking, and disease history | Green tea | The association between green tea consumption and reduced dementia risk was significant only in the 60–69 years age subgroup | 6 |
| Chuang et al. (2019) | 2019 | China | 1,436 | 260 | 11.04 years | ≥65 | ICD-9 | All caused dementia | Age, sex, education, baseline cognition, body mass index, stroke history, diastolic blood pressure, inflammation status, and stroke occurrence |
Tea | Higher intakes of both tea and fish were associated with an even lower risk od dementia | 7 |
| Fischer et al. (2018) | 2018 | Germany | 2,622 | 418 | 10 years | ≥75 | ICD-10 | All caused dementia, AD | Age, gender, BMI, education, APOE’4 carrier status, smoking status, physical activity score, depression, hypercholesterolemia, |
Black tea | Only higher red wine intake not tea was associated with a lower incidence of AD | 7 |
| Tomata et al. (2016) | 2016 | Japan | 13,645 | 1,186 | 5.7 years | ≥65 | Dementia Scale | All caused dementia | Age, sex, education level, smoking, alcohol drinking, BMI, history of disease | Green tea | Green tea consumption is significantly associated with a lower risk of incident dementia | 7 |
| Noguchi-Shinohara et al. (2014) | 2014 | Japan | 723 | 26 | 4.9 years | >60 | DSM-III-R | All caused dementia | Age, sex, history of hypertension, diabetes mellitus, hyperlipidemia, education, and ApoE4 carrier status | Green tea | No association between coffee or black tea consumption and the incidence of dementia or MCI | 6 |
| Eskelinen et al. (2009) | 2009 | Finland | 1,409 | 61 | 21 years | 65 ~ 79 | DSM-IV | All caused dementia, AD | Age, sex, education, follow-up time and community of residence, | Tea | Tea drinking was relatively uncommon and was not associated with dementia/AD | 7 |
Note:
ICD, International Classification of Diseases; BMI, body mass index; HDL, high-density lipoprotein; LDL, low density lipoprotein; CVD, cardiovascular arterial disease; DSM-III-R/DSM-IV, Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised.