Table 1 Descriptive data for study sample

Six-month sample

32

106

Total longitudinal sample

44

173

 6, 12, and 24 m scan

15

54

 6 and 12 m scan

7

28

 6 and 24 m scan

6

11

 12 and 24 m scan

7

37

 6 m scan

4

13

 12 m scan

3

22

 24 m scan

2

8

Mean age time 1

6.4 (0.4)

6.7 (0.7)

.08

Mean age time 2

12.8 (0.7)

12.6 (0.6)

.16

Mean age time 3

24.5 (0.7)

24.7 (0.7)

.92

Sex (% male)

89

58

<.001

ADOS repetitive behavior

2.7 (1.8)

0.7 (0.9)

<.001

ADOS social affect

12.0 (3.8)

2.3 (2.2)

<.001

ADOS severity score

6.0 (1.9)

1.6 (1.0)

<.001

MSEL composite

79.3 (16.9)

102.1 (15.8)

<.001

RBS-R total items endorsed

6 (0–38)^b

2 (0–27)^b

<.001

SEQ total raw score

51.7 (12.6)

39.8 (7.6)

<.001