Research studies investigating the impact of CCA on adult mental health have proliferated in recent years. However, little attention has been paid to the effect that varying operationalization can have on study results or to the possibility that the mathematical relationship of CCA to some mental health dimensions may be more complex than a basic linear association. In our data, total CCA was related to depressive symptoms, drug use, and antisocial behavior in a quadratic manner. Without further elucidation, this higher order relationship could have been interpreted as support for a sensitization process in which the long-term impact of each additional adversity on mental health compounds as childhood adversity accumulates. However, further analysis revealed that this acceleration effect was an artifact of the confounding of high cumulative adversity scores with the experience of more severe events. Thus, respondents with higher total CCA had disproportionately poorer emotional and behavioral functioning because of both the number and severity of the adversities they were exposed to, not the cumulative number of different types of adversities experienced.
Consistent with Ross and Mirowsky’s research on stressful life events (Ross & Mirowsky, 1979
), the explanatory power of CCA to predict mental health was much greater when adversities were “roughly” grouped by their severity based on estimates of impact determined on each of the mental health variables for men and women. Grouping allowed the cumulative effect to vary by impact level, our proxy measure of risk severity, and increased the efficiency of estimates. Because low-impact adversities did not present a cumulative hazard to young adult mental health, they functioned as suppressor events in the total sum score, consistent with Turner and Wheaton's (1997)
expectation. Their inclusion increased the “noise” in the score and greatly watered down the influence of high-impact events. Thus, in addition to decreasing efficiency, total scores may seriously underestimate the cumulative effects of severe forms of childhood adversity, such as abuse and serious neglect.
Differential severity of each adversity included in an aggregate index is clearly an important factor to consider when constructing a cumulative adversity variable. Our research demonstrates the problems inherent in overlooking issues of differential impact and impact severity. The alternative focus on individual adversities, as seen in the work of Brown and associates, raises parallel problems to the extent that contextual data at the individual level is not used to specify severity. Previous research has established that individual adversities differ in their impact for men and women and in relation to specific mental health conditions (Horwitz, White, & Howell-White, 1996
) and for different racial and ethnic groups (Turner & Lloyd, 2003
); identifying reference removed). Consistent with this evidence of variable impact, we found that child maltreatment variables, including sex abuse/assault, physical assault, physical abuse and serious neglect, are high impact events for both genders for depressive symptoms, but only for boys for delinquency.
Finally, what is the substantive significance of the association between exposure to many adversities and exposure to severe adversities? Whereas many of the adversities had no net impact on mental health, it is important to keep in mind current sociological understandings of stressors as structurally (not randomly) generated (Aneshensel, Rutter, & Lachenbruch, 1991
; Pearlin, 1989
) and, as such, logically interrelated micro-level events within the social system. Evidence indicates that many of these kinds of adversities are more probable for low-SES youth and their families, so it is not surprising to find that severe events, such as personally violent and injurious events, appear to be embedded in a range of lesser-impact but potentially harmful exposures (e.g., having parents separate, getting injured, parental unemployment) (e.g.,(Turner & Avison, 2003
; Turner & Lloyd, 1999
). As noted earlier, evidence indicates that severe childhood adversities are likely to affect mental health and behavior in adolescence and the transition to adulthood (See (Gore, Aseltine, & Schilling, 2007
). Whereas the experience of low-impact childhood events still allows for the preservation of social functioning and opportunities at the end of adolescence, such as pursuing higher education, severe events are more likely to further deplete psychological and social resources that are essential for this transition (Hammen, 1991
; Quinton, Pickles, Maughan, & Rutter, 1993
; Ronka & Pulkkinen, 1995
). Thus, we believe that our findings are consistent with the broader developmental research on the transition to adulthood indicating that the effects of severe adversities compromise positive choices and development in school and relationships, in turn impacting mental health (e.g., (Macmillan & Hagan, 2004
); identifying reference deleted).
Limitations and Conclusions
There are a number of limitations inherent in our data. First, as with other retrospective surveys, the assessment of childhood adversities may be subject to recall bias. We believe that our design minimized some important factors known to influence bias in that (a) we assessed childhood adversity in the early adult years when memory for childhood events should be maximized and (b) we associated childhood adversity with depressive symptoms assessed 2 years later in order to reduce the likelihood that level of depression influenced adversity memory and reporting (Schraedley, Turner, & Gotlib, 2002
). However, the influence of participants’ mental health on reports of adversity occurrence may have biased our results in other ways. In addition, our assessment of childhood adversities is not exhaustive. It is possible that unmeasured adverse childhood events and/or varying aspects of the adversities (such as age at exposure) may have biased our impact estimates in unknown ways. Finally, the self-report nature of our outcomes may have resulted in under- or over-reporting of depressive, drug, and antisocial symptoms and behaviors compared to a clinical interview. Symptom assessment based on clinical interview, and more refined and complete measurements of childhood adversity, would advance the public health and clinical significance of our results. Additional studies that attempt to replicate our findings with alternative measures of both mental health outcomes and cumulative adversity are needed to thoroughly address these limitations.
Our results have implications for other studies of CCA and mental health. Our study determined that the potency of CCA as a predictive instrument is limited to its inclusion of moderate- and high-impact adversities. Our procedures for demonstrating the empirical implications of index composition are grounded in the body of research on event-weighting schemes; however, our results cannot offer conclusive advice on how to incorporate measures of event severity into cumulative indices. Rather, we hope that our results will encourage further sensitivity to the composition of cumulative indices and in interpretation of their effects.
Our research intersects with lines of research on vulnerable populations and suggests that investments in public education and other social services must be complemented with public health efforts targeting prevention of the most severe childhood adversities. Despite the evidence for considerable variation in the impact of the different adversities, the clusters of events involving violence and threat of violence, in particular, appear to have the most pervasive impact across population subgroups and in relation to various mental health and behavioral problems. From a public health perspective, the aim may not be to identify how small sets of adversities operate in relation to specific outcomes for specific groups. Instead, programs that generally support vulnerable families and communities in an effort to minimize the conditions that promote violence may have the greatest payoff.