Table 1 Demographic, clinical, and biochemical characteristics of the study population.

Age (years)

69.4 (5.9)

69.2 (6.0)

69.7 (6.6)

0.93^a

Male/female

15/6

15/6

9/4

0.99^b

Smoking (n, %yes)

3 (14.3)

2 (9.5)

2 (15.4)

0.89^c

RLS heredity (n, %yes)

8 (38.1)

4 (19.0)

1 (7.7)

0.14^c

PD heredity (n, %yes)

7 (33.3)

9 (42.9)

1 (7.7)

0.093^b

B12 or multivitamins (n, %yes)

13 (61.9)

12 (57.1)

3 (23.1)

0.068^b

B6 or multivitamins (n, %yes)

3 (14.3)

5 (23.8)

3 (23.1)

0.76^c

Coffee consumption (cups/day)

2.5 (1.6)

2.2 (1.4)

3.7 (2.4)

0.12^a

s-Ferritin (μg/L) [30–350]

159 (86.6)

159 (105)

186 (147)

0.94^a

p-Homocysteine (μmol/L) [5–15]

15.9 (4.7)

15.0 (3.6)

15.5 (3.4)

1.0^a

s-MMA (μmol/L) [<0.37]

0.18 (0.06)

0.17 (0.06)

0.17 (0.03)

0.90^a

s-Folate (nmol/L) [>7]

22.8 (13.7)

19.6 (11.8)

18.2 (8.3)

0.67^a

p-Pyridoxal-5ʹ-phosphate (nmol/L) [20–122]^d

54.5 (32.7)

77.5 (68.9)

45.9 (26.5)

0.14^a

p-NfL (pg/mL)

6.3 (3.8)

6.2 (4.2)

6.1 (4.1)

0.95^a

 Motor duration (years)

7.9 (4.1)

7.5 (4.4)

–

0.66^e

 L-dopa duration (years)

5.1 (3.8)

4.6 (4.6)

–

0.42^e

 mH&Y (stage)

2.3 (0.4)

2.1 (0.5)

–

0.039^e

 LEDD (mg)

725 (360)

684 (308)

–

0.96^e

 No L-dopa treatment (n, %yes)

1 (4.8)

1 (4.8)

–

1.0^c

 RLS duration (years)

10.6 (11.3)

–

–

–

 IRLS (p)

18.5 (7.9)

–

–

–

 Positive SIT test^f (n, %yes)

17 (81.0)

–

–

–