Table 2B.

Association between tea-based studies (n = 30), subdivided into green tea (n = 13), black/oolong tea (n = 7), and other or non-specified tea types (n = 19) and cognitive decline/dementia

Tea-based studies
Green tea
Positive association	No association	Negative association
Ide et al. 2014 [40]	Ide et al. 2016 [41]
Gu et al. 2018	Fischer et al. 2018 [80]
(Caffeine consumption quantity and type of tea source;> 5 times/wk)
Kitamura et al. 2016 [42]	Gu et al. 2018 [51]
	(Caffeine consumption quantity; 1–5 times/wk)
Kuriyama et al. 2006 [43]	Kuriyama et al. 2006 [43]
(Caffeine consumption quantity and type of tea source; ≥ 2 cups/d)	(Caffeine consumption quantity; 4–7 cups/wk)
Lee et al. 2017 [67]	Shen et al. 2015 [53]
	(Type of tea source)
Ng et al. 2008 [76]	Shirai et al. 2020 [45]
	(Caffeine consumption quantity;< once/d)
Noguchi-Shinohara et al. 2014 [44]	Tomata et al. 2016 [47]
(Type of tea source)	(Caffeine consumption quantity;< 2 cups/d)
Shirai et al. 2020 [45]	Xu et al. 2018 [55]
(Caffeine consumption quantity; 2–3 times/d and ≥ 4 times/d)	(Sex and age; women, ≥70 years)
Tomata et al. 2016 [47]
(Caffeine consumption quantity and type of tea source;> 2 cups/d)
Xu et al. 2018 [55]
(Type of tea source, sex and age; men,< 70 years)
Black/Oolong tea
Ng et al. 2008 [76]	Feng et al. 2018 [25]
Shen et al. 2015 [53]	Kuriyama et al. 2006 [43]
(Type of tea source)	(Type of tea source)
	Noguchi-Shinohara et al. 2014 [44]
	(Type of tea source)
	Tomata et al. 2016 [47]
	(Type of tea source)
	Xu et al. 2018 [55]
	(Type of tea source)
Other/non-specified tea type
Arab et al. 2011 [32]	Arab et al. 2011 [32]
(Sex; women)	(Sex; men)
Chen et al. 2012 [49]	Broe et al. 1990 [78]
Chin et al. 2008 [82]	Chuang et al. 2019 [66]
	(Caffeine consumption quantity and sex; 2–6 times/wk, men)
Chuang et al. 2019 [66]	Dai et al. 2006 [36]
(Caffeine consumption quantity and sex; ≥ 7 times/wk, women)
Feng et al. 2012 [75]	Eskelinen et al. 2009 [28]
Huang et al. 2009 [52]	Gu et al. 2018 [51]
(Sex; men)	(Type of tea source)
Jarvis 1993 [57]	Huang et al. 2009 [52]
(Sex; women)
Lee et al. 2017 [67]	Lindsay 2002 [69]
Nurk et al. 2009 [84]	Shen et al. 2015 [53]
	(Caffeine consumption quantity; < 2 cups/d)
Shen et al. 2015	Tyas et al. 2001 [70]
(Caffeine consumption quantity;
2–4 cups/d and ≥4 cups/d)
Wang et al. 2017 [54]	Wang et al. 2017 [54]
(Age;> 60 years)	(Age;> 70 years)
Yang et al. 2016 [56]	Wu et al. 2011 [68]

Bold studies indicate multiple outcomes.