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Abstract An archival prospective design was used to study mediating and moderating variables for the association between parental divorce and increased mortality risk, using a sub-group (n=1183n=1183) of individuals from the US Terman Life Cycle Study covering the period 1921–2000. In childhood, both socioeconomic status (SES) and family psychosocial environment were related to parental divorce but did little to explain its effects. The higher mortality risk associated with experiencing parental divorce was ameliorated among individuals (especially men) who achieved a sense of personal satisfaction by mid-life. Behaviorally, smoking was the strongest mediator of the divorce-mortality link. This study extends previous work on the long-term effects of parental divorce and reveals some reasons why the stress of parental divorce in childhood need not necessarily lead to negative later-life outcomes.

Introduction Unstable families and disruptive home environments can be damaging to children, both at the time they occur, and years into the future. Repetti, Taylor, and Seeman (2002) summarize a large body of work indicating that children in “risky families”, those characterized by conflict, aggression and lack of nurturance, are vulnerable to a host of physical and mental health problems. Regarding physical health, researchers have found that abuse in childhood (Walker et al., 1999); family conflict and aggression (Lundberg, 1993; Mechanic & Hansell, 1989; Montgomery, Bartley, & Wilkinson, 1997); and neglect (Wickrama, Lorenz, & Conger, 1997; Gottman & Katz, 1989; Russek & Schwartz, 1997; Shaw, Kraus, Chattes, Connell, & Ingersoll-Dayton, 2004) are all predictive of poor outcomes. The negative effects on psychological and physical health associated with the particular stress of the divorce of one's parents during childhood are well documented (Amato, 2001; Amato & Keith (1991a) and Amato & Keith (1991b); Cherlin et al., 1991; Emery, 1999; Frustenberg & Teitler, 1994; Hetherington, Bridges, & Insabella, 1998; Tucker et al., 1997; Wallerstein, 1991). Our own work using prospective archival data found a striking effect of parental divorce on mortality risk across decades of life: on average, children from divorced families died 4 years earlier compared to their peers from non-divorced households (Schwartz et al., 1995). That study also found that parental divorce was the primary early life social predictor of life-span mortality risk and appeared independent of childhood personality. The present paper follows up on that finding. It is not the case, however, that all children of parental divorce suffer the same increases in risk. Many participants who experienced parental divorce in the Schwartz et al. (1995) study did not die earlier than average, suggesting that these individuals mitigated their risk and did not embark on a path to increased vulnerability. In much the same way that Repetti et al. (2002) propose that a combination of environmental risk factors and their physiological correlates will sometimes lead to deleterious health outcomes, a combination of mediating and/or moderating factors may allow certain individuals to withstand or even flourish in the face of a traumatic event such as parental divorce. At the psychophysiological level, there is variability in the degree to which exposure to stress creates dysregulation in responses of the sympathetic-adrenomedullary system, the hypothalamic-pituitary-adrenocortical axis, and the serotonergic system (Repetti et al., 2002; Kaufman et al., 1998; Koob, Sanna, & Bloom, 1998; Rosen & Schulkin, 1998). Similarly, at the socio-behavioral level, there is variability in the extent to which early stresses lead to health-impairing behaviors, whether they be detrimental coping strategies (such as substance abuse) or lowered levels of achievement leading to further stressors (e.g., economic difficulties after dropping out of school) (Frustenberg & Teitler, 1994; Repetti et al., 2002; Tucker et al., 1997). The present study thus addresses the question of which life pathways lead to health and well-being versus psychological maladjustment and premature mortality, in the face of parental divorce. On the one hand, a diathesis-stress model would predict that parental divorce, in combination with other risk factors, may initiate or prime a developmental process whose eventual outcome is premature death. Conversely, the stress of parental divorce combined with salutary variables may produce a strengthening experience (Park, 1998), consequently reducing the health risks. For example, coping with parental divorce may provide children with opportunities for the development of skills, mastery, and personal relationships that promote thriving (e.g., Carver, 1998; Ickovics & Park, 1998). A number of such mediating and moderating variables are suggested by past research, including family variables, socioeconomic variables, personal and behavioral variables, and social variables.

Results Parental divorce, mortality risk, and potentially explanatory variables The previous study examining mortality risk and parental divorce in the Terman sample concluded that participants who experienced parental divorce prior to 21 years of age had a significantly higher mortality risk as of the year 1991 than those whose parents remained married (n=1285n=1285, rh=1.44, p<.01p<.01) (Schwartz et al., 1995) and that these risks were independent of childhood personality. This relative hazard indicated that the experience of parental divorce was associated with an approximately 44% increase in mortality risk across the lifespan. In the present 10-year follow-up study, death data were gathered for the 1990s, and the association between experiencing parental divorce in childhood and a subsequently increased mortality risk was confirmed for the period of 1950 through 2000 (n=1183n=1183, rh=1.50, p<.001p<.001). Patterns of association between parental divorce status and potential mediating and moderating variables were next examined; these correlations appear in Table 1. Some correlations were strong and consistent for both males and females. Parental divorce was associated with fewer positive family attributes and lower adult education level for both men and women. Others demonstrated significant or marginally significant associations with parental divorce in the full sample, but failed to reach statistical significance in both the female and male sub-samples. Other variables did not demonstrate significant associations with parental divorce status in the full sample or for either gender group. Each variable was also tested for relevance to mortality risk, and the resulting relative hazards appear in Table 2. SES, the only hypothesized mediator from childhood, was not significantly related to mortality risk, but several of the proposed mediators from adulthood were predictive of mortality risk for both men and women (marital stability, life satisfaction/achievement, alcohol use, and smoking) and, as with the correlations, other variables demonstrated significant associations with mortality risk in only one gender group. Our next step was to conduct survival analyses, controlling for likely mediating variables (e.g., those that were linked to both parental divorce and mortality risk). Table 3 summarizes these analyses, showing that the association between parental divorce and mortality risk remained strong and significant when marital stability, and life satisfaction/achievement were controlled, although the Sobel's test indicates that each of these is significantly mediating the parental divorce-mortality association (ps<.05ps<.05). Education level did not significantly mediate the relationship (p>.30p>.30) and although smoking reduced the effect to only marginal significance this seems most likely due to the substantial decrease in sample size than to a particularly strong mediational effect. The final two models in Table 3 include simultaneously each of the predictors that diminished (even minimally) the parental divorce to mortality risk association in the previous survival analyses (the last model is identical to the prior except that it leaves out smoking since many participants were missing data on this variable). When these variables are included simultaneously, the parental divorce to mortality association decreases to non-significance (but not to unity) in the subsample with smoking data. Because not all associations were the same for males and females, the survival analyses were also conducted separately by sex. These analyses are presented in Table 4. For men, parental divorce remained a strong and significant predictor of mortality risk when controlling education level and marital stability and neither was a significant mediator (although both approached significance at p<.12p<.12). The association was reduced substantially, however, when life satisfaction/achievement was included (becoming only marginally significant), indicating that differences on these dimensions help to explain a significant (p<.05p<.05) portion of the difference in mortality risk seen for men from divorced vs. non-divorced families. For women, including smoking in the survival analysis model did not render the parental divorce-mortality risk relationship non-significant 5 although smoking was a significant (p<.05p<.05) mediator. The diathesis-stress hypothesis Our final step was to test the key hypothesis that some variables might be relatively unimportant in terms of predicting mortality for the sample as a whole, but for those who experienced a significant stressor (parental divorce) these variables might become more important, either placing participants at increased risk or indicating an opportunity to thrive. Interactions between parental divorce and all variables that were significantly related to it were therefore used as predictors in survival analyses. These results are listed in Table 5 and Table 6. For the sample as a whole, the interactions of parental divorce with childhood SES, life satisfaction/achievement and smoking were all significant predictors of mortality risk. Thus, these variables carry more weight in terms of their relation to mortality risk for those who are already at risk (the parental divorce sample) than they do for those from non-divorced households. In other words, individuals who had experienced parental divorce were more “protected” by positive effects associated with higher SES in childhood, better later life satisfaction and achievement, and not smoking than were those whose parents had not divorced. For males, the interaction between parental divorce and life satisfaction/achievement was significant, indicating greater risk from low satisfaction/achievement for men who had experienced parental divorce. The interaction between positive family attributes and parental divorce also approached significance for males, with boys whose seemingly functional families ended in divorce experiencing slightly higher risk than those with less positive familial qualities. Interactions between parental divorce and the remaining variables were all non-significant. For women, the only variable that interacted significantly with parental divorce was smoking, and this association was robust, indicating that despite the fact that smoking is a significant risk factor for earlier mortality, it was an even greater risk factor for women whose parents had divorced.