Table 2.
Descriptive Statistics for IQ Performance, Sociodemographic Status, Birth Condition, and Family Risk Factors
| Controls | Schizophrenia | Affective Disorders | ||||
|---|---|---|---|---|---|---|
| N | Mean (SD), % (n) | N | Mean (SD), % (n) | N | Mean (SD), % (n) | |
| Child variables | ||||||
| Cognition age 7 | 14 950 | 100.1 (15.0) | 49 | 89.1 (19.6)* | 62 | 95.9 (14.9)* |
| Cognition age 11 | 14 148 | 100.0 (15.0) | 40 | 92.1 (19.1)* | 58 | 94.9 (13.7)* |
| Gender (females) | 16 432 | 48.4% (7959) | 54 | 55.6% (30) | 65 | 60% (39) |
| School attendance age 7 | ||||||
| Below 71% attendance | 14 716 | 3.2% (477) | 49 | 6.0% (3) | 61 | 8.1% (5) |
| 71%–90% attendance | 14 716 | 30.6% (4503) | 49 | 34.6% (17) | 61 | 31.2% (19) |
| >90% attendance | 14 716 | 66.2% (9736) | 49 | 59.2% (29) | 61 | 60.7% (37) |
| BSAG age 7 | 14 821 | 8.8 (8.9) | 49 | 14.9 (11.0)** | 62 | 11.5 (9.7)*** |
| BSAG age 11 | 14 063 | 8.5 (8.10) | 40 | 14.2 (13.1)** | 57 | 12.5 (12.0)** |
| Social and economic status | ||||||
| SES (I) professional | 15 871 | 5.2% (825) | 44 | 6.8% (3) | 62 | 3.2% (2) |
| SES (II) managerial | 15 871 | 14.5% (2297) | 44 | 13.6% (6) | 62 | 22.6% (14) |
| SES (III) skilled | 15 871 | 53.1% (8425) | 44 | 54.6% (24) | 62 | 41.9% (26) |
| SES (IV) semiskilled | 15 871 | 17.4% (2761) | 44 | 11.4% (5) | 62 | 17.7% (11) |
| SES (V) unskilled | 15 871 | 6.5% (1031) | 44 | 2.3% (1) | 62 | 6.5% (4) |
| Number of male head of family | 15 871 | 3.4% (532) | 44 | 11.4% (5) | 62 | 8.1% (5) |
| Father left FT education at age 16 or younger | 10 711 | 88.3% (9458) | 22 | 63.6% (14)** | 41 | 85.4% (35) |
| Mother left FT education at age 16 or younger | 11 016 | 89.9% (9902) | 24 | 83.3% (20) | 46 | 91.3% (42) |
| Birth variables | ||||||
| OCs | 16 431 | 0.4 (0.6) | 54 | 0.5 (0.7) | 65 | 0.5 (0.8) |
| Multiple births | 16 432 | 2.2% (366) | 54 | 7.4% (4)* | 65 | 6.2% (4)*** |
| Family variables | ||||||
| Family adversity | 14 278 | 0.6 (1.4) | 44 | 1.4 (2.5)** | 58 | 0.8 (1.5) |
| Children living with both parents | 14 562 | 92.3% (13 441) | 44 | 77.3% (34)** | 58 | 81.0% (47)* |
| Children living with one parent | 14 562 | 5.5% (804) | 44 | 11.4% (5) | 58 | 12.1% (7) |
| Children living without parents | 14 562 | 2.2% (317) | 44 | 6.9% (4) | 58 | 6.9% (4) |
Note: Abbreviation is explained in the first footnote to table 1. SES, socioeconomic status; FT, full-time education; OCs, obstetric complications.
Significance of the comparison with controls: *P < .01, **P < .001, ***P < .05.