Table 1 Demographics and characteristics of the adult sample.

Age in years^a

25.44 ± 8.65

20.91 ± 2.08

29.68 ± 12.35

Sex (male)^b

95 (57%)

24 (51%)

36 (28%)

Estimated IQ^a

103.81 ± 16.48

103.60 ± 12.71

108.61 ± 15.36

Inattention^a

7.19 ± 1.74

1.72 ± 2.10

0.52 ± 1.18

Hyperactivity-impulsivity^a

5.86 ± 2.37

1.51 ± 1.59

0.70 ± 1.00

Forward digit span score^a

8.89 ± 1.98

9.00 ± 1.74

9.59 ± 1.93

Backward digit span score^a

6.42 ± 2.31

5.96 ± 2.10

7.45 ± 2.04

History of stimulants^b

78 (47%)

0

1 (0.8%)

Scan site (Nijmegen)^b

115 (69%)

21 (45%)

108 (85%)

Scan site (Amsterdam)^b

52 (31%)

26 (55%)

19 (15%)