The association between cognitive ability and externalizing problems in the context of poverty: A Nigerian adolescent twin study

Using a genetically informative design, this study investigated the mechanisms underlying the negative association between cognitive ability and externalizing problems (EXT) in adolescents from socioeconomically deprived settings. Two explanatory frameworks were evaluated: the resilience model and the health-related selection model. The resilience model would suggest that cognitive ability moderates genetic and/or environmental influences on EXT, while the health-related selection model would suggest that EXT moderates these influences on cognitive ability. A total of 3199 twin adolescents (M = 14.62, SD = 1.74) attending public schools in Lagos State, Nigeria, completed the Standard Progressive Matrices Plus (SPM) and a measure of EXT. Twin correlations and bivariate moderation model-fitting analyses were conducted. Four key findings emerged: (1) cognitive ability (SPM) moderated EXT, but not vice versa, supporting the resilience model; (2) cognitive ability moderated EXT primarily by altering shared and individual-specific environmental influences, rather than genetic influences; (3) shared and individual-specific environmental correlations between cognitive ability and EXT were significant, whereas the genetic correlation was not; and (4) among adolescents with lower cognitive ability, EXT was predominantly influenced by shared and individual-specific environmental factors, while among those with higher cognitive ability, genetic influences played a larger role alongside individual-specific environmental factors. These findings highlight the importance of incorporating cognitive ability into the development of prevention and intervention strategies for adolescents in deprived settings.