Socioeconomic risk for psychopathology: the search for causal mechanisms.

The influence of environmental factors on child psychiatric illness is terribly important. Garmezy and Masten noted that, ‘‘Ifor at least four centuries stressful life experiences have been viewed as direct etiological agents of disorders’’ (p. 191). As acute (e.g., traumatic events) and chronic (e.g., low socioeconomic status [SES]) stressors have been established as important predictors of child and adolescent psychopathology, there has been increased effort to identify the pathways through which risk is heightened in some children exposed to these stressors but not in others. For the past decade, there has been particular emphasis on the study of genetic factors and how they interact with environment as a possible explanation for differential outcomes. It is postulated that genes and environment interact (G ! E) to either promote or protect against psychopathology. The search for such genetic mechanisms can be intoxicating, clarifying, and at times overblown. For example, Risch and colleagues report in their recent meta-analyses of 14 studies that there is no evidence for the interaction between serotonin transporter gene alleles and adversity as a risk factor for depression. Their analyses revealed that adversity alone explains the greatest proportion (40%) of depression risk. It may be that chronic adversity, negative outcomes, and genetic factors are correlated, and almost certainly, G ! E research will yield important findings in the near future. However, in the interim, the results of the study by Risch et al. highlight the importance of studying the relative contributions of chronic and acute environmental adversity when attempting to understand the etiology of child psychiatric illness. Among the more widely studied chronic environmental stressors in child and adolescent psychiatry are family socioeconomic factors (e.g., income, education). Research has shown that youths from low-SES families are at risk for a variety of problems, including conduct problems and substance use, relative to their peers with higher SES. Furthermore, patients from low-SES families often lack many treatment-facilitating advantages, such as the means to pay for medication and therapy, or schools and teachers with the resources to attend to children’s mental health needs. Most mental health providers have probably wished for the power to change the neighborhood safety, family income, or school quality of their patients at some point. Acknowledging the risk associated with low SES allows for the targeting of specific populations of youths for prevention and intervention programs. However, the mechanisms and processes by which low SES influences psychological functioning must also be identified to understand how and why certain low-SES youths develop internalizing and externalizing problems, whereas others do not. As practitioners, we have little to no influence over the neighborhoods in which our patients live, or their parents’ incomes, but we can facilitate change in factors that may determine how youths function within low SES contexts, such as a child’s ability to evaluate safety and danger in his or her environment, or his/her coping skills. In this issue of the Journal, Amone-P’Olak and colleagues examine the role of life stressors as one pathway through which low SES confers risk for internalizing and externalizing problems in 2,149 adolescents ages 12 to 15 years. Interestingly, although both ‘‘person-related’’ (e.g., ‘‘dismissal from school,’’ ‘‘romantic breakup’’) and ‘‘environment-related’’ (e.g., ‘‘parental unemployment,’’ ‘‘chronic illness/handicap of family member’’) life stressors were related to internalizing and externalizing problems, only the number of environmentrelated life stressors mediated the association between low SES and psychopathology. This effect was particularly strong for internalizing disorders. The authors note that personrelated stressors may result primarily from factors other than SES, such as personality traits or psychiatric symptoms, whereas exposure to environment-related stressors is more likely to stem from the familial context, including socioeconomic position. Accepted June 18, 2009. Both authors are with the University of Vermont. Correspondence to Lynsay Ayer, B.A., University of Vermont, One South Prospect Street, Burlington, VT 05401; e-mail: Lynsay.Ayer@uvm.edu. 0890-8567/09/4810-0982!2009 by the American Academy of Child and Adolescent Psychiatry. DOI: 10.1097/CHI.0b013e3181b450ac E D I T O R I A L