Confounding and Statistical Significance of Indirect Effects: Childhood Adversity, Education, Smoking, and Anxious and Depressive Symptomatology

Abstract

The life course perspective, the risky families model, and stress-and-coping models provide the rationale for assessing the role of smoking as a mediator in the association between childhood adversity and anxious and depressive symptomatology (ADS) in adulthood. However, no previous study has assessed the independent mediating role of smoking in the association between childhood adversity and ADS in adulthood. Moreover, the importance of mediator-response confounding variables has rarely been demonstrated empirically in social and psychiatric epidemiology. The aim of this paper was to (i) assess the mediating role of smoking in adulthood in the association between childhood adversity and ADS in adulthood, and (ii) assess the change in estimates due to different mediator-response confounding factors (education, alcohol intake, and social support). The present analysis used data collected from 1994 to 2008 within the framework of the Tromsø Study (N = 4,530), a representative prospective cohort study of men and women. Seven childhood adversities (low mother's education, low father's education, low financial conditions, exposure to passive smoke, psychological abuse, physical abuse, and substance abuse distress) were used to create a childhood adversity score. Smoking status was measured at a mean age of 54.7 years (Tromsø IV), and ADS in adulthood was measured at a mean age of 61.7 years (Tromsø V). Mediation analysis was used to assess the indirect effect and the proportion of mediated effect (%) of childhood adversity on ADS in adulthood via smoking in adulthood. The test-retest reliability of smoking was good (Kappa: 0.67, 95% CI: 0.63; 0.71) in this sample. Childhood adversity was associated with a 10% increased risk of smoking in adulthood (Relative risk: 1.10, 95% CI: 1.03; 1.18), and both childhood adversity and smoking in adulthood were associated with greater levels of ADS in adulthood (p < 0.001). Smoking in adulthood did not significantly mediate the association between childhood adversity and ADS in adulthood. However, when education was excluded as a mediator-response confounding variable, the indirect effect of childhood adversity on ADS in adulthood was statistically significant (p < 0.05). This study shows that a careful inclusion of potential confounding variables is important when assessing mediation.

Physical neglect during childhood alters white matter connectivity in healthy young males

“…Internal consistency of the items (Lisofsky et al, ) and test–retest reliability (Scher, Stein, Asmundson, McCreary, & Forde, ) has been shown. Additionally, retrospective reports converge with clinical ratings of childhood maltreatment (Widom, Dutton, Czaja, & DuMont, ) and correlate with prospectively collected data (Williams, ), whereby adults minimize their degree of exposure on retrospective report (see also Sheikh, ). Thus, retrospective exposure rates are lower than prospective rates and this might lead to false negative reports but not false positive reports.…”

Education and health and well-being: direct and indirect effects with multiple mediators and interactions with multiple imputed data in Stata

“…Therefore, in the absence of alcohol intake and smoking in the models, the indirect effects presented here are likely to be overestimated 13 14. However, non-differential measurement error in the mediators would lead to underestimated indirect effects (biased downwards) 13. Consequently, the direct effects would be biased upwards 13…”

“…Some of the mediators may confound the association between other mediators and health and well-being. Indeed, it is necessary to assess whether the indirect effect is due to the mediator or some other variable that is associated with exposure, mediator and outcome in the same direction 13. Therefore, we also assessed the independent indirect effect via each mediator, adjusted for the remaining mediators (see online supplementary etable 4).…”

Childhood physical maltreatment, perceived social isolation, and internalizing symptoms: a longitudinal, three-wave, population-based study

“…With more than 60,000 inhabitants, Tromsø is the largest city in Northern Norway. The present study has a three-wave design and includes data collected from 1994 to 2008 [59,4,3]. To be eligible for the present analyses, participants had to have participated in all of the following surveys: Tromsø IV (1994-95), Tromsø V (2001-02), and Tromsø VI (2007-08) (N=4,530) [3,4].…”

“…In recent decades, there has been a great amount of research on how childhood physical maltreatment relates to affective and internalizing disorders in adulthood [1][2][3][4], and reviews [5][6][7] have shown reasonable associations between these variables. Childhood physical maltreatment can have enduring effects on brain development and brain stress regulatory flow systems, which may confer increased vulnerability to internalizing symptoms (i.e., depressive and anxious symptomatology) in later life [8,9,3,1,2]. For instance, childhood physical maltreatment may influence emotional abilities and alter sensory thresholds in ways that undermine effective emotion regulation and create increased susceptibility to internalizing disorders in later life [10,11,4,1,12].…”