However, unless these changes can be linked with outcomes in specific data sets, the causal links remain very weak. Countries that maintain national databases on illness, crime, and household structure are beginning to use record linkage to monitor changes in risk exposure, but this is not possible in the United States.
It appears that boys are more vulnerable to disorders with early onset, such as developmental disabilities, autism, disruptive behavior disorders, and ADHD (Rutter, Caspi, and Moffit, 2003). After puberty, several divergences appear. Depression and anxiety increase markedly in girls but not in boys (Rutter, Caspi, and Moffitt, 2003). Substance abuse develops faster in boys than girls, and behavioral disorders remain higher in boys (Rutter, Caspi, and Moffitt, 2003). However, sex differences can vary depending on how a disorder or its consequences are defined. For example, the DSM-IV diagnosis “conduct disorder” is not much more common in boys than girls, but boys are increasingly more likely than girls to be arrested, charged with an offense, convicted, and incarcerated (Copeland, Miller-Johnson, et al., 2007). Similarly, conduct disorder is equally common in African American and Hispanic youth, controlling for socioeconomic status and rural/urban residence (Angold, Erkanli, et al., 2002), but arrests, criminal charges, and convictions are more common in African American youth (U.S. Public Health Service, 2001c). Even in urban settings, after controlling for socioeconomic status, delinquency rates were similar in three urban and African American samples (Loeber, Wei, et al., 1999), perhaps due to the tendency for poor African American youth to be concentrated in urban ghettos (Sampson, Raudenbush, and Earls, 1997).
Epidemiology provides the basic information needed to establish the size and community burden of MEB disorders and to track the effectiveness (and cost-effectiveness) of large-scale preventive interventions. To carry out this task, a nation needs to be able to monitor the changing rates of risk exposure and illness in the population as a whole, at different developmental stages, and also in minority groups that may have different patterns of risk. Based on an amalgam of small surveys, about one in five or six young people has one or more recent MEB disorders. Retrospective studies of adults show that half or more had their first episode as a child, adolescent, or young adult. The first symptoms of most disorders precede onset of the full-blown condition by several years, so the opportunity exists for preventive intervention.