Table 1. Baseline characteristics for adolescents in the ABCD and IMAGEN cohorts, stratified by ME.
Continuous characteristics were described using mean and SD, and categorical characteristics are presented as frequency and percentages per category. P values were obtained by one-way analysis of variance (ANOVA) test for continuous variables and chi-square test for categorical variables. ns: P ≥ 0.05, *P < 0.05, **P < 0.01, ***P < 0.001. High-ME, high maternal education, defined as mother completed a university education level, the equivalent, or above; Medium-ME, medium maternal education, defined as mother completed a high school education and the equivalent; Low-ME, low maternal education, defined as mother completed less than a high school education.
| ABCD study | |||||
|---|---|---|---|---|---|
| All participants (N = 11,780) | High-ME (N = 9567) | Medium-ME (N = 1234) | Low-ME (N = 763) | P value | |
| Age (years), mean (SD) | 9.93 ± 0.64 | 9.93 ± 0.65 | 9.90 ± 0.64 | 9.89 ± 0.63 | ns |
| Male, N (%) | 6147 (52.2%) | 5000 (52.3%) | 646 (52.4%) | 370 (48.5%) | ns |
| Ethnic, N (%) | *** | ||||
| White | 7459 (63.3%) | 6571 (68.7%) | 517 (41.9%) | 276 (36.2%) | |
| Black | 1840 (15.6%) | 1156 (12.1%) | 431 (34.9%) | 199 (26.1%) | |
| Other | 2480 (21.1%) | 1840 (19.2%) | 286 (23.2%) | 288 (37.7%) | |
| Paternal education, N (%) | *** | ||||
| University, the equivalent, or above | 7313 (77.1%) | 6841 (85.6%) | 275 (33.6%) | 83 (16.5%) | |
| High school and the equivalent | 1418 (14.9%) | 879 (11.0%) | 383 (46.8%) | 122 (24.2%) | |
| Less than high school | 754 (7.9%) | 271 (3.4%) | 160 (19.6%) | 299 (59.3%) | |
| Socioeconomic condition, N (%) | *** | ||||
| ≥$100K | 4529 (42.0%) | 4414 (49.3%) | 73 (7.0%) | 7 (1.2%) | |
| $50K–$100K | 3049 (28.3%) | 2682 (30.0%) | 257 (24.6%) | 65 (11.0%) | |
| <$50K | 3193 (29.6%) | 1858 (20.8%) | 714 (68.4%) | 519 (87.8%) | |
| Intracranial volume (liters), mean (SD) | 1.49 ± 0.14 | 1.50 ± 0.14 | 1.46 ± 0.14 | 1.43 ± 0.14 | *** |
| Total brain volume (liters), mean (SD) | 0.66 ± 0.06 | 0.66 ± 0.06 | 0.64 ± 0.06 | 0.63 ± 0.06 | *** |
| IMAGEN study | |||||
| All participants (N = 2082) | High-ME (N = 1056) | Medium-ME (N = 692) | Low-ME (N = 294) | P value | |
| Age (years), mean (SD) | 14.39 ± 0.40 | 14.39 ± 0.40 | 14.40 ± 0.41 | 14.40 ± 0.40 | ns |
| Male, N (%) | 1021 (49.0%) | 522 (49.4%) | 335 (48.4%) | 148 (50.3%) | ns |
| Ethnic, N (%) | ns | ||||
| White | 1859 (89.3%) | 943 (89.3%) | 626 (90.5%) | 260 (88.4%) | |
| Black | 24 (1.2%) | 14 (1.3%) | 4 (0.6%) | 4 (1.4%) | |
| Other | 199 (9.6%) | 99 (9.4%) | 62 (9.0%) | 30 (10.2%) | |
| Paternal education, N (%) | *** | ||||
| University, the equivalent, or above | 1062 (52.3%) | 808 (77.2%) | 197 (28.9%) | 51 (18.0%) | |
| High school and the equivalent | 557 (27.4%) | 155 (14.8%) | 339 (49.8%) | 57 (20.1%) | |
| Less than high school | 411 (20.2%) | 83 (7.9%) | 145 (21.3%) | 175 (61.8%) | |
| Socioeconomic condition | 0.72 ± 1.03 | 0.58 ± 0.95 | 0.81 ± 1.07 | 0.96 ± 1.12 | *** |
| Intracranial volume (liters), mean (SD) | 1.54 ± 0.15 | 1.55 ± 0.15 | 1.53 ± 0.14 | 1.51 ± 0.15 | *** |
| Total brain volume (liters), mean (SD) | 0.60 ± 0.06 | 0.61 ± 0.06 | 0.60 ± 0.06 | 0.59 ± 0.06 | *** |