Table 1. Demographic Information for the 11 677 ABCD Study Participants Who Had Interpretable Baseline Imaging^a.

Variable	No. (%) [adjusted %]b			P valuec	Adjusted P valuec
	Category 1	Category 2	Categories 3 and 4
Total	9213 (79.0) [78.8]	2013 (17.2) [17.2]	451 (3.8) [4.0]
Boys	4756 (51.6) [50.6]	1107 (55.0) [54.1]	224 (49.8) [49.7]	.04	.12
Age, mean (SD), y	9.9 (0.62)	9.9 (0.63)	9.9 (0.62)	.46	.41
Household annual income (%, adjusted %), $
<50 000	2491 (29.6) [39.1]	542 (29.1) [38.4]	114 (27.6) [37.9]	.60	.75
≥50 000 and <100 000	2397 (28.5) [31.0]	528 (28.3) [31.3]	106 (25.7) [29.4]
≥100 000	3519 (41.9) [29.9]	794 (42.6) [30.3]	193 (46.7) [32.7]
Parental highest educational level
<High school diploma	462 (5.0) [6.2]	98 (4.9) [6.1]	20 (4.4) [5.2]	.85	.44
High school diploma/GED	862 (9.4) [10.8]	196 (9.8) [11.9]	44 (9.8) [12.4]
Some college	2390 (26.0) [29.7]	520 (25.9) [30.1]	102 (22.7) [25.1]
Bachelor	2339 (25.4) [24.2]	505 (25.1) [22.2]	121 (26.9) [26.0]
Postgraduate degree	3152 (34.2) [29.0]	689 (34.3) [29.7]	163 (36.2) [31.4]
Parents married	6199 (67.8) [61.2]	1368 (68.6) [61.9]	318 (71.3) [62.7]	.46	.94
Race/ethnicity
Asian	213 (2.3) [3.9]	43 (2.2) [3.5]	12 (2.7) [4.5]	.03	.09
Black	1446 (15.9) [14.6]	278 (14.0) [12.8]	70 (15.7) [13.7]
Other/mixedd	1628 (17.9) [15.0]	326 (16.5) [13.0]	58 (13.0) [11.1]
White	5791 (63.8) [66.5]	1334 (67.3) [70.8]	306 (68.6) [70.8]

Abbreviations: ABCD, Adolescent Brain Cognitive Development; GED, general educational development.

^aAmong the 11 679 participants with interpretable baseline imaging, 2 with category 1 findings did not have complete demographic information and were not included in this analysis.

^bPercentages are shown for both the raw numbers and the numbers predicted by applying the American Community Survey weights (adjusted %).

^cTwo-sided P values reflect randomly subsampling the data to include only 1 member of each family to control for any lack of independence owing to relatedness.

^dCategory without further subcategorization.