To investigate the effect of tea intake on cognitive function in the elderly and the mediating role of relationship of impaired activities of daily living (ADLs) and depressive states.

The data for this study came from the 2018 China Longitudinal Health and Longevity Survey (CLHLS), which included a total of 8,818 valid samples. The logistic regression was used to analyze the effects of frequency and type of tea drinking on cognitive function in the elderly, and the possible mechanism of this effect was further explored using a chain multiple mediation model.

The elderly who regularly consumed tea were less likely to develop cognitive impairment (OR=0.80, 95% CI: 0.68-0.95), in which only green tea consumption was observed to be a protective factor for the development of cognitive impairment (OR=0.81, 95%CI: 0.65-1.00), and no significant evidence was found for other types of tea. Impaired activities of daily living and depressive state mediated the effect of regular tea consumption on cognitive functioning, with beta values and 95%CIs of -0.005 (-0.008--0.001) and -0.005(-0.007--0.003), while the continuous mediating effects of the two mediating variables, although significant, had β-values that were too small and effects that accounted for too little to be of practical significance.

Regular tea consumption is associated with a reduced risk of developing cognitive impairment in the elderly, especially among those who consume green tea. Impairment in activities of daily living and depression levels almost exclusively mediated the association between tea consumption and cognitive function.