. Author manuscript; available in PMC: 2017 Nov 1.

Published in final edited form as: Autism Res. 2016 Jun 8;9(11):1169–1182. doi: 10.1002/aur.1643

Table 5.

Parameter Estimates From Nonlinear Mixed Effects Models Fitted to Total Cerebral Volume (TCV), Gray Matter, and White Matter Data for the Typically Developing (TD), ASD With Normal-Sized Brains (ASD-N), and ASD With Disproportionate Megalencephaly (ASD-DM) Subgroups. The MRI Data Were Collected at Time 1 (Mean Age 3.1 Years), 1 Year After Baseline at Time 2 (Mean Age 4.1 Years), and 1 Year Later at Time 3 (Mean 5.3 Years). For Each Nonlinear Mixed Effects Model, Age Was Centered at the Mean Age of Time 1 MRI Collection, Thus the Reported Intercepts Correspond to 37.1 Months of Age

Measure	Parameter (SE)	Group
Measure	Parameter (SE)	TD	ASD-N	ASD-DM
TCV	Intercept (cm³)	991.02 (10.00)	1012.20 (12.08)	1154.90 (18.93)^†^,^‡
	Linear slope	3.88 (0.26)	3.98 (0.33)	4.70 (0. 51)
	Quadratic slope	−0.040 (0.008)	−0.052 (0.01)	−0.081 (0.01)^***
Gray matter	Intercept (cm³)	625.59 (5.96)	640.07 (7.18)^*	719.69 (11.30)^†^,^‡
	Linear slope	1.54 (0.25)	1.36 (0.31)	1.96 (0.49)
	Quadratic slope	−0.043 (0.009)	−0.028 (0.01)	−0.055 (0.01)
White matter	Intercept (cm³)	364.85 (4.36)	374.45 (5.25)	429.46 (8.27)^†^,^‡
	Linear slope	2.23 (0.16)	2.34 (0.20)	2.38 (0.31)
	Quadratic slope	−0.0055 (0.006)	−0.028 (0.007)^**	−0.023 (0.01)

Note. Significant contrast between TD and ASD-N

P < 0.05,

^**

P < 0.01; significant contrast between TD and ASD-DM

^***

P < 0.05,

^†

P < 0.001; significant contrast between ASD-N and ASD-DM

^‡

P < 0.001.