ABSTRACT
Decades of research-and centuries of thought, re ection, and speculation-have been devoted to describing and understanding the dramatically uneven distributions of disease and misfortune within human populations. In every country, region, community, and sample in which it has been studied, the most broadly and well-replicated ndings of health services research is that 15% to 20% of the population-approximately one in ve individuals-sustains over half of the population-level morbidity and is responsible for the majority of health care visits (Boyce & Keating, 2004; Star eld et al., 1985). This maldistribution of morbidity is found in both adults (White, Williams, & Greenberg, 1961) and children (Boyce, 1992; Star eld et al., 1984), is present in both wealthy (Smedley & Syme, 2000) and impoverished (Black, Morris, & Bryce, 2003) nations, and was as characteristic of ancient civilizations (Krieger, 2001) as it is of contemporary, postmodern
societies (Syme, 1998). Inequalities in the distribution of disorders apply to “physical”/biomedical and mental illnesses as well as to problems in development and behavior. In the Cleveland Family Study (Dingle, Badger, & Jordan, 1964), for example, one third of the individual family members sustained over half of the common respiratory illnesses. The work of Star eld and colleagues (Star eld, 1991; Star eld et al., 1984) further documented the clustering of pediatric morbidities within relatively small subgroups of childhood populations and the high likelihood that children with multiple forms of ill health will carry such problems on into young adulthood. Research such as that by Rutter and Sroufe (2000) similarly indicates that disorders of mental health cluster within small groups of children, manifest-in some-continuities over time, and tend to occur with greater frequency and intensity in adverse early environments. Presyndromal behavior problems (e.g., Zahn-Waxler, Klimes-Dougan, & Slattery, 2000) and developmental disorders (e.g., Fombonne, Simmons, Ford, Meltzer, & Goodman, 2001) are also known to occur and persist (Verhulst & Van der Ende, 1995) within relatively small subsets of childhood populations. Furthermore, physical, mental, and developmental dif culties converge within such children, further burdening them with comorbidities that cross diagnostic and taxonomic categories (Bardone et al., 1998; Cohen, Pine, Must, Kasen, & Brook, 1998; Spady, Schop ocher, Svenson, & Thompson, 2005; Wells, Golding, & Burnam, 1988). Children with chronic biomedical diseases are more likely to develop psychiatric disorders, such as depression and anxiety, and those with mental disorders bear increased risks of chronic physical disease.
