Table 1 The characteristics of included studies in the systematic review

Benninger et al., 2010 [45]

RCT

25 (13/12)

63.6 ± 9.0

(IG)

64.2 ± 8.8

(CG)

2.5 ± 0.1 (IG)

2.4 ± 0.2 (CG)

22.2 ± 8.7 (IG)

17.5 ± 8

(CG)

10.6 ± 7.1

(IG)

9.1 ± 3.3

(CG)

atDCS (C3, Fp), 2 mA, 20 min, 8 sessions

None

sham tDCS (forehead), 1 mA, 1–2 min, 8 sessions

Walking time

Beretta et al., 2020 [46]

Crossover RCT

24

68.91 ± 8.47

NR

36 ± 14.32

4.84 ± 3.11

atDCS (C3, C4), 2 mA, 20 min, 1 session

None

Sham tDCS (forehead), 2 mA, 30 s-10 s-30 s, 1 session

Peak of CoP velocity

Bueno et al., 2019 [47]

Crossover RCT

20

64.45 ± 8.9

2.25 ± 0.63

22.35 ± 6.77

7.80 ± 5.32

atDCS (F3), 2 mA, 20 min, 1 session

None

Sham tDCS (F3), 2 mA, 30 s, 1 session

Gait speed, cadence, numb of step, TUG

Criminger et al., 2018 a [42]

Crossover RCT

6

68.13 ± 9.76

NR

23.44 ± 9.73

NR

atDCS (F3), 2 mA, 20 min, 1 session

None

Sham tDCS (F3), 1 mA, 30 s × 2, 1 session

TUG

Dagan et al., 2018a [43]

Crossover RCT

9

68.8 ± 6.8

2.5 ± 0.6

39.7 ± 14.6

9.0 ± 5.7

atDCS (Cz), 1.5 mA, 20 min, 1 session

None

Sham tDCS (Cz, FC1), 0.5 mA, 20 min, 1 session

FOG provoking test, TUG

Dagan et al., 2018b [43]

Crossover RCT

9

68.8 ± 6.8

2.5 ± 0.6

39.7 ± 14.6

9.0 ± 5.7

atDCS (Cz, F3), 1.5 mA, 20 min, 1 session

None

Sham tDCS (Cz, FC1), 0.5 mA, 20 min, 1 session

FOG provoking test, TUG

Kaski et al., 2014a [41]

Crossover RCT

8

NR

NR

NR

NR

atDCS (Cz), 2 mA, 15 min, 1 session

None

Sham tDCS (Cz), 2 mA, 15 min, 1 session

TUG, 6MWT, gait velocity, stride length

Lattari et al., 2017 [48]

Crossover RCT

17

69.18 ± 9.98

2.35 ± 1.06

18.0 ± 8.96

7.06 ± 2.7

atDCS (F3/F4), 2 mA, 20 min, 1 session

None

Sham tDCS (F3/F4), 2 mA, 30 s, 1 session

TUG, BBS, DGI

Manenti et al., 2014 [49]

Crossover RCT

10

67.1 ± 7.2

1.3 ± 1.1

13.3 ± 5.7

8.1 ± 3.5

atDCS (F3/F4), 2 mA, 7 min, 1 session

None

Sham tDCS (F3/F4), 2 mA, 10 s × 2, 1 session

TUG

Manor et al., 2021 [50]

RCT

71 (35/36)

71 ± 8

(IG)

69 ± 7

(CG)

NR

40 ± 14

(IG)

37 ± 17

(CG)

10 ± 6

(IG)

8 ± 6

(CG)

atDCS (F3, Cz), 1.5 mA, 20 min, 10 sessions

None

Sham tDCS, 1.5 mA, 59 s × 2, 10 sessions

TUG, FOG provoking test

Mishra et al., 2021 [51]

Crossover RCT

20

67.8 ± 8.3

1.9 ± 0.9

NR

4.8 ± 3.6

atDCS (F3), 2 mA, 30 min, 1 session

None

Sham tDCS, 2 mA, 30 s, 1 session

Gait speed

Silva et al., 2018 [52]

RCT

21 (11/10)

66 ± 5

(IG)

66 ± 10 (CG)

NR

35.5

(IG)

29.0

(CG)

(median)

6 ± 6

(IG)

5 ± 1

(CG)

atDCS (Cz, Fcz), 2 mA, 15 min, 1 session

None

Sham tDCS (Cz, Fcz), 2 mA, 10 s-30 s-10 s, 1 session

Stride length, cadence, gait duration, gait speed

Swank et al., 2016 [53]

Crossover RCT

10

68.7 ± 10.2

2 (median)

24.3

7.9 ± 7.1

atDCS (F3), 2 mA, 20 min, 1 session

None

Sham tDCS (F3), 2 mA, 30 s, 1 session

TUG

Valentino et al., 2014 [54]

Crossover RCT

10

72.3 ± 3.6

2.8 ± 0.5

32 ± 10.3

11 ± 4.9

atDCS (Cz), 2 mA, 20 min, 1 session

None

Sham tDCS (Cz), 2 mA, 30 s × 2, 1 session

Stand walk sit test, FOG-Q, num of FOG, duration of FOG, num of steps

Wong et al., 2022a [44]

RCT

12 (9/3)

54.20 ± 4.1 (IG)

58.30 ± 8.0 (CG)

1.89 ± 0.6

(IG)

1.78 ± 0.7

(CG)

33.22 ± 13.1

(IG)

23.44 ± 14.7

(CG)

93.54 ± 68.2

(IG)

100.18 ± 147.0

(CG)

(month)

atDCS (C3), 2 mA, 20 min, 1 session

None

Sham tDCS (C3), 2 mA, 30 s & 60 s, 1 session

Speed, cadence, stride time, stride length, TUG

Wong et al., 2022b [44]

RCT

12 (9/3)

50.09 ± 2.4 (IG)

58.30 ± 8.0 (CG)

1.67 ± 0.5

(IG)

1.78 ± 0.7

(CG)

25.56 ± 17.0

(IG)

23.44 ± 14.7

(CG)

73.81 ± 39.2

(IG) 100.18 ± 147.0

(CG)

(month)

atDCS (F3), 2 mA, 20 min, 1 session

None

Sham tDCS (C3), 2 mA, 30 s & 60 s, 1 session

Speed, cadence, stride time, stride length, TUG

Wong et al., 2022c [44]

RCT

12 (9/3)

61.30 ± 7.9 (IG)

58.30 ± 8.0 (CG)

2.13 ± 0.6

(IG)

1.78 ± 0.7

(CG)

24.22 ± 9.9

(IG)

23.44 ± 14.7 (CG)

93.54 ± 68.2

(IG)

100.18 ± 147

(CG)

(month)

atDCS (O3/O4), 2 mA, 20 min, 1 session

None

Sham tDCS (C3), 2 mA, 30 s & 60 s, 1 session

Speed, cadence, stride time, stride length, TUG

Chang et al., 2017 [61]

RCT

32 (16/16)

63.6 ± 7.5 (IG)

63.8 ± 8.3 (CG)

NR

NR

4.3 ± 2.5

atDCS (F3), 1 mA, 20 min, 5 sessions

rTMS (simultaneously), 10 Hz, 20 min, 5 sessions

Sham tDCS (F3) + rTMS (10 Hz, 20 min), 5 sessions

FOG-Q, TUG

Conceição et al., 2021 [63]

Crossover RCT

24

70.80 ± 7.87

NR

36.84 ± 14.31

4.3 ± 2.5

atDCS (F3/F4), 2 mA, 20 min, 1 session (after aerobic exercise 10 min)

Aerobic exercise, 30 min, 1 session

Sham tDCS (F3/F4, 2 mA, 30 s, 10 s, 30 s) + aerobic exercise (30 min), 1 session

Swing time variability, step time variability

Costa-Ribeiro et al., 2017 [55]

RCT

22 (11/11)

61.1 ± 9.1 (IG)

62.0 ± 16.7 (CG)

1–4

19.0

(IG)

19.1

(CG)

9.8 ± 4.7

(IG)

9.1 ± 5.3

(CG)

atDCS (Cz), 2 mA, 13 min, 10 sessions (before gait training)

Gait training, 30 min, 10 sessions

Sham tDCS (Cz) + gait training, 43 min, 10 sessions

TUG, BBS, cadence, 10MWT, stride length

Criminger et al., 2018b [42]

Crossover RCT

6

68.13 ± 9.76

NR

23.44 ± 9.73

6.1 ± 3.8

(IG)

6.28 ± 3.74

(CG)

tDCS during bike (F3), 2 mA, 20 min, 1 session

Bike (stationary bicycle), 20 min, 1 session

Sham tDCS (F3, 1 mA, 30 s × 2) + bike (20 min), 1 session

TUG

Criminger et al., 2018c [42]

Crossover RCT

6

68.13 ± 9.76

NR

23.44 ± 9.73

6.1 ± 3.8

(IG)

6.3 ± 3.7

(CG)

atDCS during Wii (F3), 2 mA, 20 min, 1 session

Wii game, 20 min, 1 session

Sham tDCS (F3, 1 mA, 30 s × 2) + Wii game (20 min), 1 session

TUG

Kaski et al., 2014b [41]

Crossover RCT

8

NR

NR

NR

NR

atDCS (Cz), 2 mA, 15 min, 1 session

gait training, 15 min, 1 session

sham tDCS (Cz) + physical training, 15 min, 1 session

TUG, 6MWT, gait velocity, stride length

Lee et al., 2021 [65]

RCT

30 (15/15)

70 ± 3.76 (IG)

1.33 ± 3.27 (CG)

2.47 ± 0.52

(IG)

2.8 ± 0.41

(CG)

34.2 ± 7.82

(IG)

38.67 ± 9.6

(CG)

7

atDCS (Fcz), 2 mA, 20 min, 20 sessions

Visual cueing training, 20 min, 20 sessions

sham tDCS (Fcz) + visual cueing training, 20 min, 20 sessions

FGA, FOG-Q, gait parameters

Manenti et al., 2016 [58]

RCT

20 (10/10)

69 ± 9.1

(IG)

69.1 ± 5.6 (CG)

2.2 ± 0.6

(IG)

2.3 ± 0.4

(CG)

27.8 ± 13.9

(IG)

27.6 ± 8.9

(CG)

NR

atDCS (F3/F4), 2 mA, 25 min, 10 sessions (during physical therapy)

Physical therapy, 25 min, 10 sessions

Sham tDCS (F3/F4) + physical therapy, 25 min, 10 sessions

TUG, four square step test, standing stork test, sit and reach test

Mishra et al., 2022 [64]

Crossover RCT

20

67.8 ± 8.3

1.9 ± 0.9

NR

4.8 ± 3.8

atDCS (F3), 2 mA, 30 min, 1 session (during TUG single and dual task)

TUG single and dual task, 30 min, 1 session

sham tDCS (F3) + TUG single and dual task

TUG

Na et al., 2022 [56]

RCT

23 (11/12)

63.73 ± 6.57(IG)

65.08 ± 6.46 (CG)

1

(IG)

2

(CG)

(median)

33.64 ± 16.06

(IG)

34.5 ± 12.67

(CG)

6.27 ± 1.03

(IG)

7 ± 1.41

(CG)

atDCS (Cz), 2 mA, 20 min, 10 sessions (first 20 min of 30 min training)

Treadmill gait training, 30 min, 10 sessions

Sham tDCS (Cz) + treadmill gait training, 30 min, 10 sessions

TUB, BBS, FOG, 10MWT, DGI, FRT

Fernández-Lago et al., 2017 [57]

Crossover RCT

18

73.28

1.65

21.17

NR

atDCS (C3/C4), 2 mA, 20 min, 1 session (during treadmill walking)

Treadmill training, 20 min, 1 session

Sham tDCS (C3/C4) + treadmill training, 20 min, 1 session

Gait speed, stride length,

Papen et al., 2014 [62]

Crossover RCT

10

64 ± 10

NR

29 ± 2

6.17

atDCS (C3/C4), 1 mA, 10 min, 1 session

rTMS, 1 Hz, 15 min, 1 session (immediately after tDCS)

Sham tDCS (C3/C4, 1 mA, 5 s) + rTMS (1 Hz, 15 min), 1 session

Number of steps, step length, double support, stride length, cadence

Schabrun et al., 2016 [59]

RCT

16 (8/8)

72 ± 4.9 (IG)

63 ± 11.0 (CG)

2 (median)

47.7 ± 7.5

(IG)

37.7 ± 9.8

(CG)

6.17

atDCS (C3), 2 mA, 20 min, 9 sessions (first 20 min of 60 min training)

Physical therapy, 60 min, 9 sessions

Sham tDCS (C3) + physical therapy, 60 min, 9 sessions

Gait velocity, TUG

Yotnuengnit et al., 2018 [60]

RCT

40 (20/20)

68.2 ± 9.8 (IG)

62.7 ± 8.8 (CG)

2.5 (median)

11.94 ± 4.68

(IG)

11.17 ± 3.97

(CG)

NR

atDCS (Cz), 2 mA, 30 min, 6 sessions (during physical therapy)

Physical therapy, 30 min, 6 sessions

Sham tDCS (Cz) + physical therapy, 30 min, 6 sessions

Gait speed, step length, step width, cadence