Childhood mental health difficulties mediate the long-term association between early-life adversity at age 3 and poorer cognitive functioning at ages 11 and 14.

BACKGROUND: Early-life adversity is associated with adverse mental health outcomes and poorer cognitive functioning in later development. However, little is known about how early-life adversity, mental health, and cognition affect one another or how the effects unfold over time. Here, we test the hypothesis that early-life adversity may lead to mental health challenges which in turn have adverse consequences for the development of cognitive abilities. METHODS: In a large (N = 13,287) longitudinal (5 wave) sample assessed at ages 3, 5, 7, 11 and 14, we use both path analysis approach and latent growth curve mediation model to study whether poorer mental health in childhood may mediate the effects of early-life adversity on later working memory and vocabulary outcomes. RESULTS: We found a significant total association between early-life adversity and poorer performance on working memory (ß = .123, p < .001, [95% CI 0.106, 0.141]) and vocabulary scores (ß = -.111, p < .001, [95% CI -0.129, -0.093]). Notably, current and previous mental health mediated a substantial proportion (working memory: 59%; vocabulary: 70%) of these effects. Further longitudinal modeling showed that early-life adversity has an enduring adverse effect on mental health, and that poorer mental health is associated with poorer cognitive performance later on in development. In a complementary analysis using latent growth curve mediation model, we found indirect associations between early-life adversity and working memory through baseline mental health at age 3 (intercept: ß = .083, p < .001, [95% CI 0.072, 0.094]) and change in mental health across ages 3-11 (slope: ß = -.012, p = .001, [95% CI -0.019, -0.005]). Likewise, baseline mental health at age 3 (intercept: ß = -.095, p < .001, [95% CI -0.107, -0.083]) and change in mental health across ages 3-14 (slope: ß = .007, p = .001, [95% CI 0.003, 0.011]) significantly and completely mediated the relation between early-life adversity and vocabulary outcome. CONCLUSIONS: These findings have important potential clinical and educational implications, because they suggest that academic and cognitive resilience may be supported through early mental health interventions in vulnerable children.

Cognitive variations following exposure to childhood adversity: Evidence from a pre-registered, longitudinal study.

Background: Different methodological approaches to studying the effects and timing of childhood adversity have been proposed and tested. While childhood adversity has primarily been operationalized through specificity (effects of individual adversity types) and cumulative risk (sum of all adversities reported by an individual) models, dimensional models (probeable through latent class and other cluster analyses) have recently gained traction given that it can overcome some of the limitations of the specificity and cumulative risk approaches. On the other hand, structured lifecourse modelling is a new statistical approach that examines the effects of the timing of adversity exposure on health outcomes by comparing sensitive periods and accumulation hypotheses. In this study, we apply these sets of methodological approaches and theoretical models to better understand the complex effects of childhood adversity on cognitive outcomes. Methods: We analysed data obtained from the Avon Longitudinal Study of Parents and Children for 2965 participants (Male = 1125; Female = 1840). This included parental report of 11 types of childhood adversity when participants were between 8 months and 8.7 years, and performance on inhibition, working memory and emotion recognition neurocognitive tasks when participants were 24 years of age (April 1, 1992-October 31, 2017). We used latent class analysis to classify the participants into subgroups, while we used Kruskal-Wallis test to examine differences in cognitive performance among the adversity subgroups. Additionally, to test whether sensitive period or accumulation models better explain the effects of childhood adversity on cognitive functioning, we carried out separate analyses using structured lifecourse modelling approaches. Findings: Latent class analysis showed evidence of 5 classes, namely: low adversity (71.6%), dysfunctional family (9.58%); parental deprivation (9.65%); family poverty (6.07%) and global adversity (3.1%). We observed group differences in cognitive performance among the adversity classes in an inhibition control task, χ2(4) = 15.624, p = 0.003 and working memory task, χ2(4) = 15.986, p = 0.003. Pairwise comparison tests showed that participants in the family poverty class performed significantly worse than those in the low adversity class, for the inhibition control task (p = 0.007) while participants in the global adversity class significantly performed worse than participants in the low adversity class (p = 0.026) and dysfunctional family class (p = 0.034) on the working memory task. A further analysis revealed that the associations between each individual adversity type and cognitive outcomes were mostly consistent with the observed class performance in which they co-occurred. Follow-up analyses suggested that adversity during specific sensitive periods, namely very early childhood and early childhood, explained more variability in these observed associations, compared to the accumulation of adversities. Interpretation: These findings suggest that dimensional approaches e.g., latent class analysis or cluster analysis could be good alternatives to studying childhood adversity. Using latent class analysis for example, can help reveal the population distribution of co-occurring adversity patterns among participants who may be at the greatest health risk and thus, enable a targeted intervention. In addition, this approach could be used to investigate specific pathways that link adversity classes to different developmental outcomes that could further complement the specificity or cumulative risk approaches to adversity. On the other hand, findings from a separate analysis using structured lifecourse modelling approaches also highlight the vital developmental timeframes in childhood during which the impact of adversity exposure on cognitive outcomes is greatest, suggesting the need to provide comprehensive academic and mental health support to individuals exposed during those specific timeframes. Funding: T.N. received funding from Cambridge Trust (University of Cambridge).