Joint developmental trajectories of internalising and externalising behaviours from childhood to adolescence and their links to socio-economic profiles - findings from the 'growing up in Ireland' cohort.

introductionCompared to their more affluent peers, children of low socioeconomic position (SEP) are more likely to experience poor mental health. Correctly identifying factors that influence internalising and externalising symptoms is imperative for early, targeted intervention. Distinguishing between symptoms that are transient and chronic, and singular or co-morbid is important. We investigated how internalising and externalising behaviours co-occur in children from childhood to adolescence, and examined the association between these behaviours and childhood family- and child-level risk factors - including maternal characteristics, economic strain and experiences in childhood.

methodUsing the large, nationally representative, longitudinal sample from the Growing Up in Ireland study, two mixture modelling techniques were applied: Latent Class Analysis to unveil multidimensional family profiles by clustering subjects with similar familial, maternal and lived experiences, and Group-Based Multi-Trajectory Model to identify joint behavioural trajectories based on responses to the internalising and externalising subscales of the Strength and Difficulty Questionnaire, measured at three time points (age 9, 13 and 17). OUTCOME: Half of the children (51%) showed no behavioural problems, however a large proportion of children experienced substantial economic strain while growing up in Ireland during the 2000s. Worse SEP conditions were linked to less advantageous maternal characteristics, e.g. mothers who were young, smoked and did not breastfeed. A clear gradient of troubled behaviour was seen as socio-economic difficulties increased. Changes in family profiles were associated with minor or modest alterations in behavioural outcomes. Implications for policy are discussed.