TABLE 3.

Summary of the Mixed-Effects Models Examining the Effect of Diagnostic Group, Sex, and Corresponding Hemisphere Volume on Left and Right Hippocampal Volume (mm³)

	Left			Right
Effect	Estimate	SE	p	Estimate	SE	p
Intercept	3,336.26	28.33	<.001	3,512.23	31.05	<.001
Sex (female)	−67.24	32.46	.04	−57.79	35.55	.11
Age (months)	8.65	1.37	<.001	7.37	1.51	<.001
ASD diagnosis	−24.06	30.90	.44	−−15.16	33.90	.66
Hemisphere volume (cm3)	3.06	0.46	<.001	2.73	0.51	<.001
Age × sex (female)	−0.75	0.82	.36	−1.16	0.96	.23
Age × ASD diagnosis	−3.33	1.35	.01	−1.93	1.46	.19
Age × age	−0.03	0.03	.19	−0.02	0.03	.61
Hemisphere × ASD diagnosis	1.19	0.54	.03	1.62	0.59	.007

Note: Age was centered at 38 months and hemisphere at 498.91 cm³. Thus, the intercept represents predicted volume for 38-month-old typically developing male participants with 498.91 cm³ hemisphere volume. ASD = autism spectrum disorder; SE = standard error.