Table 1.

Risk Ratio Estimates (OR) for Schizophrenia and Affective Disorders Depending on IQ at Ages 7 and 11

IQ Groups (Group Mean)	N	Schizophrenia			Affective Disorders
		Risk (Number of Cases)	Crude OR (95% CI)	Adjusted ORa (95% CI)	Risk (Number of Cases)	Crude OR (95% CI)	Adjusted ORb (95% CI)
Age 7 years	15 061	49		N = 14 167			N = 14 167
<−2 SD<70 (63.5)	509	0.0157 (8)	8.40 (3.66–19.28)	7.89 (3.00–20.72)	0.0079 (4)	1.93 (0.69–5.40)	1.23 (0.36–4.26)
<−1 SD70−84 (78.2)	1969	0.0081 (16)	4.31 (2.21–8.39)	2.72 (1.18–6.25)	0.0066 (13)	1.62 (0.86–3.02)	1.12 (0.54–2.34)
<±1 SD85–115 (101.0)	10 017	0.0019 (19)	1.00	1.00	0.0041 (41)	1.00	1.00
>+1 SD>115 (119.9)	2566	0.0023 (6)	1.23 (0.49–3.09)	1.18 (0.45–3.10)	0.0016 (4)	0.38 (0.14–1.06)	0.34 (0.10–1.09)
Age 11 years	14 1246	40		N = 13 880			N = 13 880
<−2 SD<70 (65.8)	206	0.0194 (4)	10.69 (3.57–32.05)	9.01 (2.75–29.50)	0.0097 (2)	2.43 (0.58–10.13)	1.64 (0.38–7.14)
<−1 SD70−84 (79.1)	2121	0.0056 (12)	3.07 (1.47–6.44)	2.51 (1.10–5.75)	0.0061 (13)	1.53 (0.81–2.882)	1.16 (0.59–2.28)
<±1 SD85–115 (99.1)	9193	0.0018 (17)	1.00	1.00	0.0040 (37)	1.00	1.00
>+1 SD>115 (121.7)	2726	0.0025 (7)	1.39 (0.58–3.35)	1.27 (0.49–3.29)	0.0022 (6)	0.55 (0.23–1.30)	0.69 (0.29–1.66)

Note: BSAG, Bristol Social Adjustment Guide.

^aConfounders: father’s years in education; multiple birth; BSAG total score at age 7; relation with natural parents at age 7.

^bConfounders: multiple birth; BSAG total score at age 7; relation with natural parents at age 7.

^cConfounders: father’s years in education; BSAG total score at age 11; relation with natural parents at age 11.

^dConfounders: multiple birth; BSAG total score at age 11; relation with natural parents at age 11.