Demographic data
The demographic data of participants were shown in Table 1. In ASD group, the chronological age and BMI were 32.1±6.1 months, 21.0±5.0 kg/m2, respectively. Among them, 14 cases (28%) were females, and 36 cases (72%) were males. Chronological age and BMI between different genders were not statistically significant (P>0.05) in both ASD and TD groups. Furthermore, there was no statistical difference in demographic data (gender, chronological age and BMI) between the two groups (P>0.05).
We evaluated cognitive profile in the ASD and TD groups based on gender differences. The mean of FSIQ, verbal IQ (VIQ) and performance IQ (PIQ) scores were significantly higher (FSIQ: 109.5 versus 100; VIQ: 107.9 versus 99.6; PIQ: 106.1 versus 93.0; P < 0.05 for all) in TD group than ASD group. The mean of VIQ score in ASD-Males were significantly higher (VIQ: 106.3 versus 90.2, P < 0.05 ) than in ASD-Females. However, there was no statistical difference in cognitive profile between TD-Males and TD-Females.
Table 1 Demographic characteristics of participants
Variables
|
Total (N=100)
|
ASD (N=50)
|
TD (N=50)
|
PTotal
|
PASD
|
PTD
|
ASD
|
TD
|
Males
|
Females
|
Males
|
Females
|
Gender
|
n(%)
|
-
|
-
|
36 (72)
|
14 (28)
|
33 (66)
|
17 (34)
|
0.517
|
-
|
-
|
BMI
(kg/m2)
|
Mean ± SD
|
21.0 ± 5.0
|
21.1 ± 4.0
|
20.9 ± 5.5
|
21.5 ± 3.6
|
21.5 ± 4.6
|
21.4 ± 2,7
|
0.641
|
0.686
|
0.911
|
Range
|
14.5 - 31.2
|
16.1 - 30.5
|
14.5 - 36.2
|
16.1 - 27.3
|
16.1 - 34.5
|
18.0 - 27.9
|
|
|
|
Age
(months)
|
Mean ± SD
|
32.1 ± 6.1
|
33.2 ± 5.7
|
32.4 ± 6.6
|
31.9 ± 4.7
|
32.6 ± 5.5
|
33.1 ± 6.0
|
0.414
|
0.450
|
0.698
|
Range
|
24 – 47
|
25 - 45
|
24 - 49
|
25 - 39
|
25 - 45
|
27 - 43
|
|
|
|
Cognitive
variables
|
|
|
|
|
|
|
|
|
|
|
FSIQ
|
Mean ± SD
|
100.0 ± 11.2
|
109.5 ± 5.9
|
97.3 ± 11.1
|
92.29 ± 9.9
|
109.5 ± 6.4
|
110.7 ± 4.3
|
0.000
|
0.150
|
0.536
|
Range
|
74 - 121
|
97 - 119
|
77 - 121
|
76 - 104
|
97 - 121
|
99 - 116
|
|
|
|
VIQ
|
Mean ± SD
|
99.6 ± 10.9
|
107.9 ± 6.5
|
106.3 ± 6.4
|
90.2 ± 8.7
|
107.7 ± 7.4
|
108.3 ± 4.8
|
0.000
|
0.000
|
0.754
|
Range
|
78 - 118
|
96 - 122
|
83 - 118
|
78 - 106
|
96 - 122
|
101 - 116
|
|
|
|
PIQ
|
Mean ± SD
|
93.0 ± 9.7
|
106.1 ± 4.4
|
96.4 ± 9.1
|
93.9 ± 11.2
|
105.6 ± 4.6
|
106.7 ± 3.1
|
0.000
|
0.426
|
0.480
|
Range
|
74 - 113
|
97- 120
|
94 - 118
|
89 - 113
|
96 - 113
|
104 - 120
|
|
|
|
ASD, autism spectrum disorder; TD, typically developing; SD, standard deviation ; BMI, body mass index; FSIQ, full - scale intelligence quotient; VIQ, verbal intelligence quotient; PIQ, performance intelligence quotient.
CC size
We calculated the CC size in children by using FREESURFER v6.0, and tried to investigate the differences in the volume of CC and its sub-regions between ASD and TD groups. A series of 2 × 2 ANCOVA analyses, with five sub-regions and TCC volumes as dependent variables, gender as fixed factors, and age and BMI as covariates revealed no significant effect of gender on all these measures or their interaction (all P > 0.05). No significant differences in PCC, MCC and ACC volumes (P = 0.410, P= 0.926 and P = 0.909, respectively) were observed between ASD and TD groups, but MPCC, AMCC and TCC volumes in ASD group was higher (MPCC: [0.39±0.07] cm3 versus [0.31±0.03] cm3; AMCC: [0.48 ± 0.09] cm3 versus [0.40 ± 0.07] cm3; TCC: [2.71 ± 0.28] cm3 versus [2.52 ± 0.20] cm3; P < 0.05 for all) than that in TD group (Table 2).
We compared the CC size between ASD and TD groups according to gender differences. As depicted in Figure 2, The MPCC, AMCC and TCC volumes of ASD-Females were significantly higher than that of ASD-Males and TD-Females (P < 0.05), but the difference of CC size between TD-Males and TD-Females was not statistically significant (P > 0.05). There was no statistically significant difference in ACC, MCC and PCC volumes among ASD-Female, ASD-Male, TD-Female, and TD-Male (all P > 0.05).
Table 2 CC size in ASD and TD groups (mean ± SD)
Variables
|
ASD (n=50)
|
TD (n=50)
|
t
|
P value
|
PCC
|
0.70 ± 0.10
|
0.68 ± 0.11
|
- 0.827
|
0.410
|
MPCC
|
0.39 ± 0.07
|
0.31 ± 0.03
|
- 6.889
|
0.000
|
MCC
|
0.41 ± 0.06
|
0.41 ± 0.04
|
- 0.093
|
0.926
|
ACC
|
0.71 ± 0.08
|
0.72 ± 0.09
|
- 0.114
|
0.909
|
AMCC
|
0.48 ± 0.09
|
0.40 ± 0.07
|
- 4.654
|
0.000
|
TCC
|
2.71 ± 0.28
|
2.52 ± 0.20
|
- 3.879
|
0.000
|
All values are in cubic centimeters and correspond to the sum of the corresponding values for the left and right hemisphere. PCC, posterior corpus callosum; MPCC, mid-posterior corpus callosum; MCC, middle corpus callosum; ACC, anterior corpus callosum; AMCC, anterior-middle corpus callosum; TCC, Total corpus callosum.
Autistic symptoms
The differences of autistic symptoms between genders in ASD were depicted in Table 3. ASD-Males and ASD-Females did not differ in severity of autism as measured with scores at the AS and ADI-R (P = 0.092 and P=0.887, respectively). However, there were gender differences in the scores of AT and AC (both P < 0.05), with lower scores in males than in females.
Table 3 Relationship between gender differences and autistic symptoms in ASD group
Variables
|
Males (n=36)
|
Females (n=14)
|
t
|
P value
|
AS
|
Mean ± SD
|
6.5 ± 1.4
|
7.2 ± 1.1
|
1.721
|
0.092
|
Range
|
5 – 9
|
7 - 9
|
|
|
AC
|
Mean ± SD
|
5.9 ± 1.6
|
7.5 ± 1.0
|
3.379
|
0.000
|
Range
|
4 – 9
|
7 - 9
|
|
|
AT
|
Mean ± SD
|
12.4 ± 2.5
|
14.7 ± 1.9
|
3.029
|
0.004
|
Range
|
8 – 18
|
11 - 18
|
|
|
ADI - R
|
Mean ± SD
|
2.4 ± 0.7
|
2.4 ± 0.7
|
0.143
|
0.887
|
Range
|
1 – 3
|
1 - 3
|
|
|
ADOS,Autism Diagnostic Observation Schedule; AS, ADOS social; AC, ADOS communication; AT, ADOS total; ADI - R, Autism Diagnostic Interview-Revised; SD, standard deviation.
Correlation between the volumes of CC and clinical features
The severity of clinical features of ASD was judged according to the scores of clinical assessment scales including AC, AS, AT, ADI-R, VIQ, PIQ and FSIQ. Table 4 showed the correlation between the clinical features and CC size. There were significant and positive correlations between AC score and MPCC volume (r = 0.693; n = 50; P < 0.01), as well as among AC score and ACC, AMCC, TCC volumes (r = 0.412, 0.625 and 0.859, respectively; all P < 0.01), with higher MPCC, ACC, AMCC and TCC volume being associated with more serious symptom levels. Furthermore, the scores of AS and AT were also positively related to MPCC, AMCC and TCC volumes (all P < 0.01). In terms of IQ, VIQ score was significantly and negatively associated with MPCC, AMCC and TCC volumes (r = -0.576, -0.471 and -0.635, respectively; all P < 0.01). FSIQ score was also significantly and negatively associated with ACC, AMCC, TCC volumes (r = -0.494, -0.525 and -0.679, respectively; all P < 0.01).
According to the above results, we could preliminarily judge that the gender differences of AC, AT and VIQ in ASD may be related to MPCC, AMCC and TCC volumes. Therefore, we observed divergent effects of MPCC, AMCC and TCC volumes on some clinical features (AC, AT and VIQ) in ASD by gender grouping, as seen in Figure 3. The effects of MPCC, AMCC and TCC volumes were more homogenous on AC, AT and VIQ. In males and females, both AC and AT scores increase with the change of MPCC, AMCC and TCC volumes, but VIQ decline.
Table 4 Correlations between the CC size and clinical assessment scale in ASD group
|
AC
|
AS
|
AT
|
ADI - R
|
VIQ
|
PIQ
|
FSIQ
|
PCC
|
0.191
|
0.081
|
0.209
|
0.041
|
-0.176
|
-0.132
|
-0.415**
|
MPCC
|
0.673**
|
0.466**
|
0.656**
|
0.198
|
-0.576**
|
-0.038
|
-0.494**
|
MCC
|
0.045
|
0.086
|
0.048
|
0.147
|
-0.010
|
0.021
|
-0.175
|
ACC
|
0.412**
|
0.160
|
0.340*
|
0.059
|
-0.252
|
0.006
|
-0.290*
|
AMCC
|
0.625**
|
0.448**
|
0.632**
|
0.133
|
-0.471**
|
-0.023
|
-0.525**
|
TCC
|
0.859**
|
0.629**
|
0.858**
|
0.366**
|
-0.635**
|
0.048
|
-0.679**
|
All values in the table are ‘r’, *P < 0.05, **P < 0.01.