ABSTRACT

Introduction:
Dementia is a neurodegenerative disease in which environmental and lifestyle factors, including dietary habits, appear to play an important etiologic role. In particular, the effects of tea and coffee consumption are still under debate, having shown both protective and risk effects. This review aimed to assess the dose-response relation between coffee and tea consumption and risk of dementia.

Methods:
We performed a systematic literature search to identify relevant studies using the electronic databases PubMed and EMBASE until December 9, 2025. Inclusion criteria were: population free of chronic diseases and without previous diagnosis of dementia, assessment of tea or coffee intake and of the risk of developing dementia, and cohort or cohort-nested case-control design. We assessed the quality of the studies with the ROBINS-E tool. We performed nonlinear dose-response modeling of dementia for increasing tea and coffee consumption.

Results:
Ten studies were included in the analysis, with more than 450,000 participants at baseline and mean follow-up duration of 11.5 years. We found a progressive and linear decrease in all-cause dementia risk with increasing tea consumption, with comparable results for all tea types and for green tea only. Coffee demonstrated a U-shaped relation with the lowest risk between 2-3 cups/day (about 300/450 mL/day). The relation with Alzheimer's dementia showed no difference in risk until 3 cups of coffee per day when risk started to increase.

Conclusions:
This study shows that moderate coffee consumption does not seem to affect dementia risk, while high coffee consumption (≥3 cups/day) could increase risk of all-cause dementia and Alzheimer's dementia. Conversely, tea consumption appears to linearly decrease all-cause dementia risk, while for Alzheimer's dementia there seems to be no further decrease in risk with consumption above one cup/day.

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