Since the DSM-IV appeared in 1994, an impressive amount of new information about CD has emerged. New biological correlates of CD have been discovered, resulting in a whole new world of intriguing physiological, neuroimaging, and genotype biomarkers associated with CD. Longitudinal birth cohorts launched in the 1970s and 1980s have now reached adulthood, and powerful new statistical procedures have been created to dissect the repeated measures from these cohorts, giving us our first views of conduct-problem trajectories from early childhood to mid-life. Groups formerly overlooked in CD research, such as girls and preschool children, have received vigorous research attention in the past 5 years, with provocative results. A concept formerly considered to be relevant to adults only, psychopathic callous-unemotional traits, has been successfully transported into the world of child and adolescent CD research. Progress in genetics research has recently revived enthusiasm about the potential of family-psychiatric-history data for understanding CD.
On one hand, these scientific advances change the way researchers and clinicians think about CD, and as a result, these advances generate some serious contenders for changing the diagnostic protocol for CD in DSM-V. On the other hand, our background work for this article indicated that the current DSM-IV CD protocol is widely considered to be very good, as it is. We found no serious proposals to delete any of the current criteria for CD, or to shift the threshold for diagnosis up or down to ‘correct’ the prevalence rate of CD. Subtyping by age of onset enjoys a supportive evidence base, and although the age-of-onset system may need some tweaking, clinicians and researchers appear to be using it. In both research and clinical settings, using dimensional conduct-problem scales alongside the categorical CD diagnosis is already considered good practice, and reliable and valid dimensional scales are available. The current CD protocol involves a straightforward count of observable symptom behaviors; it is not much challenged by the complexities that engender controversy for other disorders (e.g., about core symptoms, requisite numbers of symptoms within different criterion sets, dubious subtypes, or blurred boundaries between strongly overlapping disorders). Overall, the current protocol for CD is short and simple, and it performs fairly well, at least in research settings. Finally, many pundits believe that DSM-V and ICD should maintain the status quo unless there is overwhelming evidence that obliges a change; even modest changes could transfigure patients’ access to health-care and educational services, confuse the use of diagnoses in the courts, and undermine the cumulative nature of scientific research into mental disorders.
The contenders for change that we identified and reviewed here are mostly proposals to add something to the existing CD diagnostic protocol for DSM-V: a childhood-limited subtype, family psychiatric history, callous-unemotional traits, various and sundry biomarkers, female-specific criteria, preschool-specific criteria, or early substance use. Reasonable rationales have been put forward for adding each of these. However, in the absence of serious dissatisfaction with the current CD protocol, these contenders will have to present a far more compelling evidence base than is now available if they are to be considered for incorporation into DSM-V. Thus, we hope that vigorous efforts will be undertaken to meet the many research needs raised in this article. In particular, we found little evidence that biomarkers are ready to be incorporated into DSM-V, or even mentioned as associated features, because most biomarkers lack evidence of specificity to CD, evidence that they predict prognosis, and evidence that they can be translated for routine clinical use. We hope future biomarker research will take seriously our challenge to address questions of specificity, prediction, and translation.
To our surprise, although there is a great deal of interesting research into each of the 11 issues we reviewed in this article, very little of it has been strategically aimed toward providing the sort of evidence base that will be required to justify any alteration to the DSM-V. We found that many case–control comparisons have already been carried out; these have documented that each of the 11 issues reviewed here is relevant to CD, and brought each to attention in the field. This article recommends other key designs that are fundamental for answering questions about whether or not an issue should be incorporated into DSM-V. Epidemiological cohort studies are needed to assess a diagnostic criterion’s prevalence across age, sex, and race/ethnicity. Such cohort studies can also report the prevalence of ‘abnormal’ scores in the healthy population. If a criterion were added to the CD diagnosis, what rate of false positives would be expected? Cohort studies can also reveal whether the criterion in question is distributed as a category or a continuum in the population. Psychiatric controls are needed to evaluate the specificity of a diagnostic criterion to CD versus other disorders. Longitudinal follow-up studies are needed to test if a criterion improves prediction of CD children’s course and prognosis. Such studies should follow up community cohorts, clinical samples, and forensic samples to insure that findings apply broadly. Subtype comparisons are needed because a criterion that seems to be only modestly related to CD children overall may in fact be strongly related to one specific subtype. Translational research is needed to convert researcher’s data-collection paradigms into assessment tools that are practical in clinical and forensic settings. Psychometric evaluations are needed to assess the test–retest and inter-rater reliability of new assessment tools for CD. Clinical trials are needed to identify whether potential CD diagnostic criteria can predict treatment compliance or treatment response. These research approaches are urgently needed to prepare for DSM-V.