Table 1 Sample characteristics

Age (years)

4.6

0.8

4.8

0.8

4.7

0.7

IQ^a

55.7

16.6

46.3

14.1

70.5

32.1

RBS-R

Overall score

20.5

14.5

27.1

17.0

26.9

13.7

Stereotyped

5.7

3.4

7.4

3.5

5.9

3.7

Self-injurious

2.1

2.4

2.6

2.7

2.0

2.6

Compulsive

2.3

2.3

3.4

3.2

4.9

3.1

Ritualistic

2.4

2.8

3.4

3.8

4.2

2.9

Brain volume (cm ³ )

Intracranial volume

1350.4

89.9

1359.7

108.5

1381.1

1452.7

Caudate left

4.6

0.8

4.9

1.0

3.8

0.6

Caudate right

4.8

0.8

4.9

0.9

4.0

0.6

Amygdala left^b

1.9

0.2

1.9

0.2

2.2

0.3

Amygdala right^b

1.7

0.2

1.7

0.2

2.1

0.3