Suicidal behavior among adolescents: correlates, confounds, and (the search for) causal mechanisms.

The death of a child is a tragedy. When a child commits suicide, the loss is particularly devastating. Unfortunately, such deaths are common because suicide is a leading cause of death worldwide and the third leading cause of death among children and adolescents in the United States. Preventing suicide in these age groups requires that we develop a better understanding of why children and adolescents kill themselves. Explanatory models in clinical science typically develop by identifying correlates of the outcome of interest and conducting well-controlled, prospective, experimental studies to identify causal relations among variables, followed by more fine-grained studies aimed at delineating causal mechanisms (i.e., the pathways or processes through which the correlate influences the outcome). The development and testing of explanatory models is more challenging in the case of suicidal behavior, given the clinical, ethical/legal, and methodological challenges that characterize this work. For instance, although suicide is a leading cause of death, suicidal behaviors have a relatively low base rate in the population, thus studies of suicidal behaviors typically require large sample sizes to test the complex models that will be needed to understand and predict suicidal behavior. In addition, concerns about failing to adequately monitor or treat suicidal behavior, or about increasing suicidal behavior in response to an experimental manipulation, often preclude the use of experimental designs. Furthermore, the stigma associated with suicidal behaviors can lead to underreporting or to avoidance of research studies altogether. As a result, although studies of suicidal behavior have provided valuable information about the correlates of these outcomes, many questions remain about the nature of these correlations (e.g., what are the mediators and moderators?) and about the causal mechanisms through which these relations exist. For instance, dozens of research studies have shown that suicidal behavior occurs at higher rates among those who are female, are adolescents, have a history of violence (or victimization), have a family history of mental disorders, and have a mental or alcohol/substance use disorder. However, little is known about how or why each of these factors is correlated with suicidal behavior. Why do girls make more suicide attempts than boys? Why are there such enormous racial/ethnic differences in suicide rates? How or why are mental disorders like depression and alcohol abuse/dependence associated with suicidal behavior? Three articles in this issue of the Journal overcome many of the limitations of previous work in this area and, in doing so, move us further along the path from knowledge of correlation to understanding of causality. Notably, each study uses a large (N 9 1,000) and representative sample of adolescents, and each goes beyond simple tests of bivariate correlations to provide fine-grained information about the nature of the relations between previously identified correlates and suicidal behaviors. The prevalence of suicidal behaviors varies significantly across countries, cultures, and racial/ethnic groups around the world. In the United States, although 90.5% of suicides occur among European Americans, the suicide rate for black adolescent male subjects has risen significantly during the past several decades and now approximates that of European Americans. The article by Joe and colleagues, which examines the prevalence and correlates of suicidal ideation and attempts among a nationally representative sample (N = 1,170) of black adolescents in the United States, is especially important, given this context. The authors document that 7.5% of black adolescents report seriously thinking about killing themselves at some point in their lifetime, and 2.7% report a past suicide attempt, underscoring the broad scope of this problem. The Accepted November 7, 2008. Dr. Nock is with the Department of Psychology, Harvard University. Correspondence to Matthew Nock, Ph.D., Department of Psychology, Harvard University, 33 Kirkland Street, Cambridge, MA 02138; e-mail: nock@wjh. harvard.edu. 0890-8567/09/4803-0237 2009 by the American Academy of Child and Adolescent Psychiatry. DOI: 10.1097/CHI.0b013e318196b944 E D I T O R I A L