Table 1 Characteristics of the included RCTs (n = 24)

Cinar et al. 2020; [45] Turkey

SCD^c

60 (30/30)

PC^d

No intervention

12 (or at least 1200 min of training)

about 7 (15–20 min)

Home

Amjad et al. 2019; [50] Pakistan

MCI^e - not specified

38 (18/20)

VR^f

Physical exercises (motion, stretching)

6

5 (20–30 min)

Lab

Barnes et al. 2009; [51] USA

MCI - all types

47 (22/25)

PC

Alternative computer-based activities

6

5 (100 min)

Home

Damirchi et al. 2018; [52] Iran

MCI - not specified

44 (11/11/13/9)

IG1: PC

Waiting list group

8

3 (30 min in weeks 1–6;

60 min in 7^th and 8^th week)

Lab

IG2: Physical activity group

IG3: IG1 combined with physical group activities

Dimitriadis et al. 2016; [53] Greece

MCI - not specified

158 (53/50/55)

AR^g

CG1: Alternative computer-based activity

10

4 (90 min)

Home

CG2: Waiting list group

Finn et al. 2011; [54] Australia

MCI - amnestic multiple domain

16 (8/8)

PC

Waiting list group

average of 11.4 ^h

4–5 (not reported)

Home

Flak et al. 2019; [55] Norway

MCI - all types

69 (35/34)ⁱ

PC

Same intervention as in IG but in contrast with fixed low level of difficulty

5

5 (30–40 min)

Home

Hagovska et al. 2017; [46] Slovakia

MCI - not specified

60 (30/30)

PC

Group cognitive training program

10

2 (30 min)

Lab

Han et al. 2017; [56] South Korea

MCI - all types

43 (43/42)^j

Tablet

Usual treatment

4

2 (30 min)

Lab

Herrera et al. 2012; [57] France

MCI - amnestic multiple domain

22 (11/11)

PC

Cognitive training

12

2 (60 min)

Lab

Hyer et al. 2016; [58] USA

MCI - amnestic and non-amnestic

68 (34/34)

PC

Same intervention as in IG but in contrast with fixed low level of difficulty

5–7

about 5 (40 min)

Lab or Home

Li et al. 2019; [59] China

MCI - amnestic (due to AD^k)

141 (78/63)

PC

No intervention

24

3–4 (about 40 min)

Home

Lin et al. 2016; [60] USA

MCI - amnestic multiple domain (due to AD)

21 (10/11)

PC

Cognitive training

6

4 (60 min)

Home

Nousia et al. 2019; [48] Greece

MCI - all types

46 (25/21)

PC

Usual treatment

15

2 (60 min)

Lab

Park et al. 2019; [49] South Korea

MCI - single and multiple domain

21 (10/11)

Mixed Reality

Computer-based cognitive training

6

3 (30 min)

Lab

Park et al. 2020; [61] South Korea

MCI - amnestic

21 (10/11)

VR

Waiting list group

12

2 (30 min)

Lab

Rosen et al. 2011; [62] USA

MCI - amnestic

12 (6/6)

PC

Alternative computer-based activities

Average of 8 ^l

5 (100 min)

Home

Savulich et al. 2017; [63] United Kingdom

MCI - amnestic (due to AD)

42 (21/21)

Tablet

No intervention

4

not reported (60 min)

Lab

Thapa et al. 2020; [64] South Korea

MCI - not specified

68 (34/34)^m

VRⁿ

Educational program on general health care

8

3 (100 min)

Lab

Cinar et al. 2020; [45] Turkey

Dementia - AD

60 (30/30)

PC

No intervention

12 (or at least 1200 min of training)

about 7 (15–20 min)

Home

Galante et al. 2007; [65] Italy

Dementia - AD

12 (7/5)^o

PC

Interviews on current affairs and participants’ lives

4

3 (60 min)

Lab

Heiss et al. 1994; [66] Germany

Dementia - AD

70 (18/17/18/17)

IG1: PC

Social support

24

2 (60 min)

Lab

IG2^p: IG1 combined with medication

IG3^p: IG1 combined with medication

Karssemeijer et al. 2019; [67, 68] The Netherlands

Dementia - all types

115 (38/38/39)

IG1: VR (combined with cycling on a stationary bike)

Physical exercises (relaxation, flexibility)

12

3 (30–40 min)

Lab

IG2: Cycling on a stationary bike

Lee et al. 2013; [47] China

Dementia - AD

19 (7/6/6)

IG1: Tablet

Waiting-list control group with cognitive activities

6

2 (12–30 min)

Lab

IG2: Cognitive training without Tablet

Yu et al. 2015; [69] China

Dementia - not specified

32 (16/16)

Tablet

Cognitive training

4–8

1–2 (30 min)

Lab