Tea consumption and risk of incident dementia: A prospective cohort study of 377 592 UK Biobank participants

Abstract

As a widely consumed beverage, tea boasts diverse health benefits. Herein, we aimed to investigate the association between tea consumption and dementia risk. We conducted a prospective cohort study with 377 592 UK Biobank participants during a 9-year follow-up. Cox regression models adjusted for age, sex, ethnicity, Townsend deprivation index, education, body mass index, lifestyle factors, dietary factors and apolipoprotein E4 status were used to examine the association of tea consumption with dementia risk. Subgroup analyses stratified by age, sex and forms of dementia (Alzheimer's disease [AD] and vascular dementia [VD]) were performed. Moreover, the restricted cubic splines were used to calculate the nonlinear relationship between daily dosage of tea and dementia risk. After adjustment for all covariates, tea drinkers were 16% (95% confidence interval: 8-23) less likely to develop dementia compared with non-drinkers. Moderate consumption (1-6 cups/day) of tea exerted significant protective effects. Subgroup analyses showed that mid-aged participants or males benefited more from tea consumption. Moreover, moderate drinkers had a 16-19% lower hazard of AD and a 25-29% lower hazard of VD. Furthermore, a U-shaped association between tea consumption and dementia risk was shown (P_{non-linearity} = 7E^-04), and the consumption of around three cups per day showed the strongest protective effect. Within 3 cups/day, drinking one extra cup of tea per day brought a 6% reduction of incidence. In conclusion, moderate consumption of tea was significantly associated with a reduced risk of dementia, suggesting that tea consumption could be a modifiable lifestyle factor for dementia.

Fig. 1. Flowchart of participant selection.

TDI Townsend deprivation index, BMI Body mass index, APOE4 apolipoprotein E4.

Fig. 2. Association between tea consumption and the risk of incident dementia.

In both adjusted models, tea consumption was associated with a reduced risk of dementia (model 1: HR = 0.819 [95% CI:0.760-0.884]; model 2: HR = 0.841 [95% CI: 0.767–0.921]). Moderate consumption (1–6 cups/day) of tea exerted significant protective effects. P values were computed by Cox proportional hazard regression. Model 1 was adjusted for age, sex and ethnicity. Model 2 was adjusted for 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. HR Hazard ratios, CI Confidence interval, TDI Townsend deprivation index, BMI Body mass index, APOE4, apolipoprotein E4.

Fig. 3. Associations of tea consumption with risks of AD and VD in the fully-adjusted model.

After adjusting for all covariates, participants who consumed 1–4 cups of tea a day were 16–19% less likely to develop AD compared with non-drinkers. Besides, the tea consumption of 1–6 cups/day brought a 25 to 29% reduction in VD incidence. P values were computed by Cox proportional hazard regressions. Covariates included 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. HR Hazard ratios, CI Confidence interval, AD Alzheimer disease, VD Vascular dementia, TDI Townsend deprivation index, BMI Body mass index, APOE4 apolipoprotein E4.

Fig. 4. A non-linear relationship between tea consumption and incident dementia.

There was a U-shaped association between tea consumption and incident dementia, and the consumption of around three cups per day showed the strongest protective effect (P for non-linearity = 7E^-04). P-value was computed using restricted cubic splines functions in the Cox proportional hazard regression model. The model was adjusted for 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. HR Hazard ratios, CI Confidence interval, TDI Townsend deprivation index, BMI Body mass index, APOE4 apolipoprotein E4.