Examining the association between cognitive ability and emotional problems across childhood using a genetically informative design: could there be a causal relationship?

BACKGROUND: Emotional problems co-occur with difficulties in verbal and nonverbal cognitive ability, yet the pathways underlying their association remain poorly understood: It is unclear whether effects may be causal, and to what extent they may run from cognition to emotion, or vice versa. METHODS: Our preregistered analyses included 5,124 twin pairs from the Twins Early Development Study (TEDS). At ages 7, 9 and 12, emotional problems were assessed through the strengths and difficulties questionnaire, and cognition was assessed using task-based measures. Cross-lagged models examined the influence of cognition and subdomains of verbal and nonverbal abilities on emotional problems and vice versa, across development. Genetic cross-lagged models examined the effect of cognition on emotional problems and vice versa, after controlling for shared genetic and environmental influence. RESULTS: Cross-lagged paths in both directions were observed between cognitive ability and emotional problems (from -0.11 to -0.05). Cross-lagged associations that persisted after accounting for common genetic and environmental influences were between nonverbal ability and emotional problems. Higher emotional problems at age 7 predicted lower nonverbal ability at age 9, with 22% of the phenotypic association remaining. This, in turn, predicted greater emotional problems at age 12, with 13% of the association remaining. CONCLUSIONS: Genetic and environmental factors accounted for a large proportion of the cross-lagged associations. Emotional problems in early childhood could result in a cascade effect, leading to lower nonverbal cognition in middle childhood, which increases the risk of emotional problems in late childhood. These findings highlight the importance of age- and domain-specific interventions.