Table 2.

Associations of demographic covariates with attention deficit hyperactivity disorder symptoms.

Phenotype (IV)	B	SE	p	R2
Age	−0.004	0.005	0.450	0.000
Pubertal status	−0.105	0.049	0.031	0.001
Sex (male)	1.036	0.073	<0.001	0.023
Handedness	0.325	0.051	<0.001	0.005
Internalizing symptoms	0.323	0.006	<0.001	0.259
Parent’s highest education (high school)	−0.089	0.247	0.719	0.009
Parent’s highest education (some college)	0.116	0.221	0.598	0.009
Parent’s highest education (bachelor’s)	−0.301	0.222	0.175	0.009
Parent’s highest education (graduate)	−0.706	0.219	0.001	0.009
Child race (Black)	0.267	0.118	0.024	0.003
Child race (Asian)	−1.001	0.265	<0.001	0.003
Child race (other)	0.321	0.106	0.003	0.003
Parent’s income ($50,000–100,000)	−0.524	0.102	<0.001	0.009
Parent’s income (>$100,000)	−0.874	0.096	<0.001	0.009
Medication status	5.131	0.132	<0.001	0.150
EN-back motion	1.003	0.190	<0.001	0.005
SST motion	1.131	0.251	<0.001	0.004
MID motion	2.299	0.238	<0.001	0.015
Average motion	1.591	0.128	<0.001	0.018
Intracranial volume	0.027	0.036	0.458	0.000

Age, pubertal status, handedness, and internalizing symptoms were analyzed as continuous variables. Sex, parent’s education, parent’s income, child’s race, and medication status were analyzed as categorical variables. Sample size reflects sMRI analyses (which includes all subjects in fMRI analyses) for all rows except motion. For multi-category variables (e.g., race and income) R² represents the variance explained by all dummy variables for a given category. For race “White” was used as the reference category; for income “<$50,000” was used as the reference category, for parent’s highest education “Less than a high school degree” was used as the reference category.

B unstandardized regression coefficient, SE standard error of regression coefficient, t t-statistic of regression coefficient, p alpha value of regression coefficient, R² variance explained by that variable.