Table 1 Participant characteristics

Mak et al. (2003)

(N = 13) Controls-6, PD-7

Controls—69.2 (63–72) PD—66.9 (53–73)

Stage 2.5–3

_

–

On phase

Inkster et al. (2002)

(N = 20) Controls-10, Men with mild PD-10

Controls—65.5 (53.1–77.9) PD—64.1 (54–74)

Stage 1–3

On state—11

off state—17.4

_

On and off phase

Pääsuke et al. (2004)

(N = 28) Controls-16, Females with PD-12

Controls—71.7 (66.7–75.5) PD—74.3 (67.4–81.2)

Stage 1–3

_

4 to 18 years, with a mean of 10.7 (4.5) years

On phase

Ramsey et al. (2003)

(N = 24) Controls-13, Men with PD-11

Controls—73.4 (66.7–80.1) PD—70 (62.9–77.5)

Stage 2

_

_

On phase

Mak et al. (2002)

(N = 40) Controls-20, PD-20

Controls—69.3 (64.2–74.4) PD—65.80 (58.56–73.04)

Stage 2–3

16.22 to 30.48, mean score of 23.35

5.68 (2.03–9.33) years

On phase

Bishop et al. (2005)

(N = 41) PD-41

PD—66 (50–79)

Stage 1–3

Motor subscale part III, average 4–58

0.5 to 14 years

On phase

Inkster et al. (2004)

(N = 20) Controls-10, PD-10

Controls—65.5 (53.1–77.9) PD—64.1 (54–74.2)

Stage 2

On state—11

off state—17.4

2.5 to 5.5 years, with a mean of 4 years

On and off phase

Buckley et al. (2008)

(N = 24) Controls-12, PD-12

Controls—63 (61–65) PD—63 (60–66)

Stage 1–3

_

8 to 14 years, mean duration of 11 years

On phase

Nikfekr et al. (2002)

(N = 13) Controls-7, PD-6

Controls—54 (45–65) PD—56 (49–68)

Stage 1.5–2

Motor subscale—14.6 range = 13–18

_

Off phase

De Souza et al. (2011)

(N = 15) Controls-7, PD-8

Controls—63.7 (58.9–68.5) PD—63.8 (54.3–73.3)

Stage 2–3

_

7.4 (3.9–10.9) years

On phase

Souza et al. (2018)

(N = 71) PD-71

63.4 (50–75)

Stage 2–3

Motor-section score 6 to 54 mean = 28.3

2 to 30 years, mean duration of 8.7 years

Off phase

Mak et al. (2004)

(N = 30) Controls-15, PD-15

Controls—69.5 (64.3–74.7) PD—65.5 (57.6–73.4)

Stage 2–3

16.6 to 30, mean score of 23.2

_

On phase

Fernandes et al. (2015)

(N = 18) Controls-9, PD-9

Controls—63.89 years (52–80) PD—66 (52–80)

Stage 1–2.5

_

4.48 to 15.6 years

On phase