Do Depressive Traits and Hostility Predict Age-Related Decline in General Intelligence?

Table 4

Obvious depression scale: effects on WAIS IQs from 50 to 80.

Model	Coefficient^1	95% CI	𝑃 for main effect	Interaction^2 coefficient	𝑃 for interaction
Full-scale IQ
Model 1: unadjusted^3	−0.639	(−0.83)–(−0.44)	<0.001	0.003	0.319
Model 2: demographics^4	−0.184	(−0.35)–(−0.02)	0.029	0.003	0.291
Model 3: lifestyle factors^5	−0.190	(−0.36)–(−0.03)	0.023	0.003	0.294
Verbal IQ
Model 1: unadjusted^3	−0.572	(−0.77)–(−0.38)	<0.001	0.002	0.638
Model 2: demographics^4	−0.119	(−0.28)–(0.05)	0.156	0.002	0.613
Model 3: lifestyle factors^5	−0.125	(−0.29)–(0.04)	0.131	0.002	0.616
Performance IQ
Model 1: unadjusted^3	−0.595	(−0.78)–(−0.41)	<0.001	0.005	0.227
Model 2: demographics^4	−0.223	(−0.40)–(−0.05)	0.012	0.005	0.236
Model 3: lifestyle factors^5	−0.228	(−0.40)–(−0.06)	0.009	0.005	0.236

¹Fixed effect coefficient from a model only including the main effect of the depression scale. See Section 3 for description of the effects of obvious depression on the estimates of the random effects.
²Interaction coefficient from a model including a term for interaction between the obvious depression scale and time since baseline. Additionally all relevant main effects are included in the model.
³Model includes linear and quadratic time since baseline and the obvious depression scale.
⁴Model additionally includes sex, education, and social status.
⁵Model additionally includes sex, education, social status, systolic blood pressure, smoking, BMI, total cholesterol, triglycerides, insulin, and leisure and work physical activity.