Table 1. Descriptive Statistics.
| Characteristic | No. (%) | |||||
|---|---|---|---|---|---|---|
| Overall | 1982-1991 | 1992-1995 | 1996-1999 | 2000-2003 | 2004-2008 | |
| Swedish Twin Registry | ||||||
| No. | 23 639 | 6079 | 4829 | 4656 | 4404 | 3671 |
| Sex/zygosity | ||||||
| MZF | 3091 (13.1) | 1100 (18.1) | 655 (13.6) | 521 (11.2) | 513 (11.6) | 302 (8.2) |
| DZF | 2831 (12.0) | 643 (10.6) | 618 (12.8) | 643 (13.8) | 609 (13.8) | 318 (8.7) |
| MZM | 2604 (11.0) | 742 (12.2) | 593 (12.3) | 488 (10.5) | 468 (10.6) | 313 (8.5) |
| DZM | 2959 (12.5) | 466 (7.7) | 739 (15.3) | 720 (15.5) | 705 (16.0) | 329 (9.0) |
| DZOS | 11 193 (47.3) | 2983 (49.1) | 1914 (39.6) | 1918 (41.2) | 2036 (46.2) | 2342 (63.8) |
| Unknown | 961 (4.1) | 145 (2.4) | 310 (6.4) | 366 (7.9) | 73 (1.7) | 67 (1.8) |
| ASD descriptives | ||||||
| Clinical ASDa | 715 (1.5) | 140 (1.2) | 157 (1.6) | 176 (1.9) | 160 (1.8) | 82 (1.1) |
| Child and Adolescent Twin Study in Sweden | ||||||
| No. | 15 524 | NA | 3777 | 3932 | 3825 | 3990 |
| Sex/zygosity | ||||||
| MZF | 2377 (15.3) | 612 (16.2) | 542 (13.8) | 529 (13.8) | 694 (17.4) | |
| DZF | 2503 (16.1) | 597 (15.8) | 670 (17.0) | 626 (16.4) | 610 (15.3) | |
| MZM | 2201 (14.2) | 571 (15.1) | 512 (13.0) | 481 (12.6) | 637 (16.0) | |
| DZM | 2891 (18.6) | 745 (19.7) | 754 (19.2) | 720 (18.8) | 672 (16.8) | |
| DZOS | 5308 (34.2) | 1208 (32.0) | 1401 (35.6) | 1409 (36.8) | 1290 (32.3) | |
| Unknown | 244 (1.6) | 44 (1.2) | 53 (1.3) | 60 (1.6) | 87 (2.2) | |
| ASD descriptives | ||||||
| A-TAC ASD, mean (SD) | 0.85 (1.65) | 0.80 (1.57) | 0.75 (1.54) | 0.79 (1.58) | 1.03 (1.85) | |
| Broad ASD | 1244 (4.0) | 274 (3.6) | 247 (3.1) | 284 (3.7) | 439 (5.5) | |
| Clinical ASDa | 434 (1.4) | 127 (1.7) | 139 (1.8) | 126 (1.6) | 42 (0.5) | |
Abbreviations: ASD, autism spectrum disorder; A-TAC, Autism, Tics, Attention-Deficit/Hyperactivity Disorder, and Other Comorbidities Inventory; DZF, dizygotic female; DZM, dizygotic male; DZOS, dizygotic opposite sex; MZF, monozygotic female; MZM, monozygotic male; NA, not applicable.
a
Clinical ASD, recorded ASD diagnosis in the National Patient Register; Broad ASD, screening diagnosis of ASD, based on scoring 4.5 or more on the A-TAC.