Context: Individuals with lower IQ scores have an increased risk of psychological disorders, mental health problems, and suicide; similarly, children with low IQ scores are more likely to have behavioral, emotional, and anxiety disorders. However, little is known about the effect of parental IQ on the mental health outcomes of their children.
Objective: To determine whether maternal and paternal IQ scores are associated with offspring conduct, emotional, and attention scores.
Design: Cohort study.
Setting: General population.
Participants: Members of the 1958 National Child Development Study and their offspring were studied. Of 2984 parent-offspring pairs with nonadopted children 4 years or older, 2202 pairs had complete data regarding all variables of interest and were included in the analyses.
Main outcome measures: Offspring conduct, emotional, and attention scores based on the Behavioral Problems Index for children aged 4 to 6 years or the Rutter A scale for children and adolescents 7 years and older.
Results: Little evidence was observed of any association of parental IQ with conduct or emotional problems in children aged 4 to 6 years. However, among children and adolescents 7 years or older, strong evidence was observed from age- and sex-adjusted models to support a decrease in conduct, emotional, and attention problems in those whose parents had higher IQ scores. These associations were linear across the full IQ range. Individual adjustments for socioeconomic status and the child's own IQ had limited effect. However, adjustments for Home Observation for Measurement of the Environment scores and parental malaise attenuated associations with the mother's IQ but had little effect on associations with the father's IQ (scores were available for only 1 parent for each child or adolescent). Strong associations were no longer evident in models that simultaneously adjusted for all 4 potential mediating variables.
Conclusions: Children whose parents score poorly on IQ tests may have an increased risk of conduct, emotional, and attention problems. The home environment, parental malaise, and the child's own IQ may have a role in explaining these associations.