Table 1.
Sample characteristics of the study population, 1 701 206 adults in Norway
| Variable | ADHD, No. (%) | Non‐ADHD, No. (%) | ADHD Women, No. (%) | ADHD Men, No. (%) |
|---|---|---|---|---|
| No. (%) | 40 103 (2.4) | 1 661 103 (97.6) | 17 815 (44.4) | 22 288 (55.6) |
| Gender | ||||
| Women | 17 815 (44.4) | 812 061 (48.9) | ||
| Men | 22 288 (55.6) | 849 042 (51.1) | ||
| M:F ratio | 1.25 | 1.05 | ||
| Mean age in 2015 (years) (SD) | P < 0.001a | P < 0.001b | ||
| 31.2 (8.3) | 33.1 (9.3) | 31.4 (8.4) | 31.0 (8.2) | |
| Gestational age (weeks) | P < 0.001a | P < 0.001b | ||
| <27 | 113 (0.3) | 2464 (0.2) | 43 (0.3) | 70 (0.3) |
| 28–31 | 283 (0.8) | 7835 (0.5) | 101 (0.6) | 182 (0.9) |
| 32–34 | 677 (1.9) | 22 239 (1.4) | 270 (1.7) | 407 (2.0) |
| 35–36 | 1313 (3.6) | 49 624 (3.2) | 532 (3.3) | 781 (3.8) |
| 37–41 | 28 552 (77.9) | 1 250 422 (80.3) | 12 660 (77.8) | 15 892 (78.1) |
| 42+ | 5701 (15.6) | 223 779 (14.4) | 2661 (16.4) | 3040 (14.9) |
| Missing | 3464 (8.6) | 104 740 (6.3) | 1548 (8.7) | 1916 (8.6) |
| Maternal marital status | P < 0.001a | P = 0.9b | ||
| Married/cohabitant | 32 342 (80.9) | 1 489 193 (89.8) | 14 354 (80.8) | 17 988 (80.9) |
| Single | 6708 (16.8) | 152 884 (9.2) | 2996 (16.9) | 3712 (16.7) |
| Other | 944 (2.4) | 16 250 (1.0) | 419 (2.4) | 525 (2.4) |
| Missing | 109 (0.3) | 2776 (0.2) | 46 (0.3) | 63 (0.3) |
| Maternal educational status | P < 0.001a | P = 0.8b | ||
| Low | 13 892 (34.9) | 432 778 (26.2) | 6197 (35.0) | 7695 (34.7) |
| Middle | 17 061 (42.8) | 771 795 (46.7) | 7629 (43.1) | 9432 (42.6) |
| High | 8903 (22.3) | 449 945 (27.2) | 3877 (21.2) | 5026 (22.7) |
| Missing | 247 (0.6) | 6585 (0.4) | 112 (0.6) | 135 (0.6) |
| Paternal educational status | P < 0.001a | P = 0.006b | ||
| Low | 12 889 (33.0) | 382 793 (23.4) | 5695 (32.8) | 7194 (33.2) |
| Middle | 19 320 (49.5) | 838 027 (51.2) | 8746 (50.4) | 10 574 (48.8) |
| High | 6827 (17.5) | 416 636 (25.4) | 2914 (16.8) | 3913 (18.1) |
| Missing | 1067 (2.7) | 23 647 (1.4) | 460 (2.6) | 607 (2.7) |
| Maternal psychiatric disorder | P < 0.001a | P = 0.99b | ||
| None | 29 149 (72.7) | 1 437 851 (86.6) | 12 977 (72.8) | 16 172 (72.6) |
| Any, including ADHD | 10 953 (27.3) | 223 216 (13.4) | 4838 (27.2) | 6115 (27.4) |
| Paternal psychiatric disorder | P < 0.001a | P = 0.06b | ||
| None | 32 667 (82.7) | 1 485 656 (90.1) | 14 609 (83.2) | 18 058 (82.2) |
| Any, including ADHD | 6848 (17.3) | 162 779 (9.9) | 2941 (16.8) | 3907 (17.8) |
a
P‐value (Pearson's chi‐square test and t‐test for equality of means) for the difference in ADHD total relative to the comparison population.
b
P‐value (Pearson's chi‐square test and t‐test for equality of means) for the difference in men with ADHD vs. women with ADHD.