Table 1 Characteristics of included studies and participants

Barban et al. (2016) [43]

6

RCT (crossover design)

Probable early-stage AD

NINCDS-ADRDA

CDR: 1

TG: 23.4 (1.9)

CG: 23.4 (1.7)

TG: 42

CG: 39

TG: 76.7 (5.7)

CG: 76.9 (5.7)

TG: 13/29

CG: 11/28

TG: 8.8 (3.6)

CG: 9.2 (3.7)

Italy, Greece, Norway, and Spain

Co-funded by the European Union in the SOCIABLE project

Belleville et al. (2018) [33]

7

RCT (3-arm design)

MCI

Petersen’s diagnostic criteria for MCI

Not reported

TG1: 40

^aTG2: 43

CG: 44

TG: 71.3 (8.5)

^aTG2: 72.1 (6.7)

CG: 73.1 (6.5)

TG1: 20/20

^aTG2: 19/24

CG: 18/26

TG1: 14.5 (4.2)

^aTG2: 14.7 (3.5)

CG: 14.8 (3.8)

Canada

Funded by the Canadian Institutes for Health Research

Giuli et al. (2016) [41]

6

RCT (crossover design)

MCI

Petersen’s diagnostic criteria for MCI

TG: 25.7 (1.8)

CG: 25.8 (1.9)

TG: 48

CG: 49

TG: 76.0 (6.3)

CG: 76.5 (5.7)

TG: 17/31

CG: 19/30

TG: 6.7 (3.8)

CG: 5.3 (3.0)

Italy

Funded by the Italian Ministry of Health and the Marche Region

Probable early-stage (mild) AD

DSM-IV or NINCDS-ADRDA

TG: 20.2 (3.7)

CG: 20.3 (3.5)

TG: 48

CG: 47

TG: 76.5 (4.3)

CG: 78.7 (5.9)

TG: 19/29

CG: 13/34

TG: 5.9 (4.1)

CG: 4.5 (2.3)

Lam et al. (2015) [21]

6

RCT (4-arm design)

MCI

International Working Group on MCI diagnostic criteria

CDR: < 1

TG1: 25.7 (2.4)

TG2: 25.2 (2.2)

TG3: 25.8 (2.3)

CG: 25.6 (2.4)

TG1: 145

^aTG2: 132

TG3: 147

^bCG: 131

TG1: 74.4 (6.4)

^aTG2: 76.3 (6.6)

TG3: 75.5 (6.7)

^bCG: 75.4 (6.1)

TG1: 30/115

^aTG2: 28/104

TG3: 34/113

^bCG: 29/102

TG1: 3.9 (3.8)

^aTG2: 3.4 (3.3)

TG3: 4.0 (3.6)

^bCG: 4.0 (3.9)

Hong Kong

Funded by a donation from the Simon KY Lee Fund for the Elderly in Hong Kong

Law et al. (2019) [34]

7

RCT (4-arm design)

MCI

NIAAA criteria

Not reported

TG1: 15

^aTG2: 16

TG3: 14

CG: 14

TG1: 76.9 (6.8)

^aTG2: 77.9 (6.1)

TG3: 71.6 (7.4)

CG: 75.1 (8.5)

TG1: 7/8

^aTG2: 8/8

TG3: 4/10

CG: 5/9

Not reported as average years

n (illiterate/primary/secondary/tertiary)

TG1: 4/6/5/0

^aTG2: 5/3/7/0

TG3: 4/5/4/1

CG: 3/7/3/1

Hong Kong

Funded by the Research Grants Council (RGC) of the Hong Kong University Grants Committee

Law et al. (2022) [38]

7

RCT (4-arm design)

MCI

NIAAA criteria

Not reported

TG1: 38

^aTG2: 37

^aTG3: 34

CG: 36

TG1: 76.3 (7.2)

^aTG2: 77.4 (6.7)

^aTG3: 73.2 (7.3)

CG: 74.1 (7.5)

TG1: 13/25

^aTG2: 16/21

^aTG3: 11/23

CG: 12/24

Not reported as average years

n (illiterate/primary/secondary/tertiary)

TG1: 8/15/13/2

^aTG2: 9/8/13/7

^aTG3: 9/12/8/5

CG: 9/14/9/4

Hong Kong

The Research Grants Council, University Grants, Committee of Hong Kong, SAR, China

Muñiz et al. (2015) [22]

8

RCT (parallel design)

MCI or probable early-stage (mild) AD

Flicker et al. criteria for MCI

NINCDS-ADRDA

TG: 17.6 (0.7)

CG: 17.4 (1.0)

TG: 40

CG: 40

TG: 74.9 (1.1)

CG: 73.4 (1.0)

TG: 17/23

CG: 14/26

TG: 8.1 (0.6)

CG: 7.3 (4.4)

Spain

None described

Nousia et al. (2018) [40]

6

RCT (parallel design)

Probable early-stage (mild) AD

NINCDS-ADRDA

Not reported

TG: 25

CG: 25

TG: 76.2 (5.14)

CG: 76.3 (5.38)

TG: 9/16

CG: 5/20

TG: 8.08 (3.01)

CG: 8.92 (2.83)

Greece

None described

Pantoni et al. (2017) [35]

6

RCT (parallel design)

MCI

International Working Group on MCI diagnostic criteria

TG: 27.1 (2.6)

CG: 25.7 (3.2)

TG: 21

CG: 22

TG: 74.2 (6.0)

CG: 75.9 (7.6)

TG: 13/8

CG: 15/7

TG: 9.0 (5.3)

CG: 7.4 (3.0)

Italy

Funded by the Tuscany region and Italian Ministry of Health

Park (2022) [39]

7

RCT (parallel design

MCI

Petersen’s diagnostic criteria for MCI

MMSE Korean version

TG: 26.06 (1.34)

CG: 25.50 (1.31)

TG: 16

CG: 16

TG: 72.3 (5.13)

CG: 70.9 (4.51)

TG: 9/7

CG: 6/10

TG: 7.56 (3.93)

CG: 7.50 (2.89)

Korea

Ministry of Education of the Republic of Korea and the National Research Foundation of Korea

Rojas et al. (2013) [36]

4

RCT (parallel design)

MCI

Petersen’s diagnostic criteria for MCI

CDR: 0.5

TG: 27.53 (2.33)

CG: 27.13 (2.10)

TG: 15

CG: 15

TG: 72.0 (14.3)

CG: 76.9 (7.1)

TG: 9/6

CG: 8/7

TG: 10.53 (3.78)

CG: 10.53 (3.85)

Argentina

Co-funded by Ministry of Health of the city of Buenos Aires, Argentina, and CONICET

Rovner et al. (2018) [37]

6

RCT (parallel design)

MCI

NIAAA criteria

TG: 25.8 (2.3)

CG: 25.6 (2.5)

TG: 111

CG: 110

TG: 75.5 (7.1)

CG: 76.2 (6.90)

TG: 25/86

CG: 21/89

TG: 12.6 (2.2)

CG: 12.4 (2.9)

USA

Funded by the National Institute on Aging

Williams et al. (2014) [42]

6

RCT (3-arm design)

MCI or mild dementia

8-item ascertain dementia score > 2

TG 1: 25.6 (2.7)

^aTG 2: 25.7 (2.7)

CG 2: 24.7 (3.1)

TG 1: 29

^aTG 2: 28

CG 2: 32

TG 1: 86.0 (5.9)

^aTG 2: 83.0 (10.5)

CG 2: 86.0 (4.8)

TG 1: 12/17

^aTG 2: 6/22

CG 2: 11/21

TG 1: 13.30 (2.6)

^aTG 2: 15.65 (1.8)

CG 2: 13.56 (2.4)

USA

Funded by the National Institute of Nursing Research and the National Institute of Deafness and Communication Disorders