Cognitive ability, parental socioeconomic position and internalising and externalising problems in adolescence: findings from two European cohort studies

Abstract We investigated whether cognitive ability (CA)
may be a moderator of the relationship of parental socioeconomic
position (SEP) with internalising and externalising
problems in adolescents. We used data from two
longitudinal cohort studies; the Avon Longitudinal Study
of Parents and Children (ALSPAC) and the Tracking
Adolescents’ Individual Lives Survey (TRAILS). Indicators
of SEP were mother’s education and household
income. CA was estimated with IQ scores, derived from
the Wechsler Intelligence Scale for Children. Internalising
and externalising problems were measured with the
Strengths and Difficulties Questionnaire in ALSPAC and
with the Child Behavior Checklist in TRAILS. Logistic
regression analyses were used to estimate the relative index
of inequality (RII) for each outcome; the RII provides the
odds ratio comparing the most to least deprived for each
measure of SEP. In fully adjusted models an association of
mother’s education with externalising problems was
observed [ALSPAC RII 1.42 (95%CI: 1.01–1.99); TRAILS
RII 2.21 (95%CI: 1.37–3.54)], and of household income
with internalising and externalising problems [pooled
ALSPAC & TRAILS internalising RII 1.30 (95%CI: 0.99–
1.71); pooled ALSPAC & TRAILS externalising RII 1.38
(95%CI: 1.03–1.84)]. No consistent associations were
observed between mother’s education and internalising
problems. Results of stratified analyses and interactionterms
showed no evidence that CA moderated the association
of SEP with internalising or externalising problems.