What we need to know about callous-unemotional traits: comment on Frick, Ray, Thornton, and Kahn (2014).

Frick, Ray, Thornton, and Kahn (2014) presented a comprehensive and well-articulated review of studies relevant to the validity and utility of using callous-unemotional traits to subtype the diagnosis of conduct disorder (CD). Like definitions of subtypes of CD in previous versions of the Diagnostic and Statistical Manual of Mental Disorders, the available evidence on the validity of the new subtypes of CD in the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5; American Psychiatric Association, 2013) based on callous-unemotional traits is thin. Nonetheless, the target article makes a compelling argument for further study of callous-unemotional and related traits to better understand the heterogeneity of CD. In particular, the possibilities that callous-unemotional traits may facilitate understanding of etiology and psychobiological mechanisms and may help predict the prognosis and treatment outcomes of children with CD deserve greater study. Future research must be stronger than previous research, however, in using more appropriate samples of children with CD along with more informative designs, and in conducting analyses to directly test the incremental validity of callous-unemotional traits as a subtyping variable beyond the severity or aggressiveness of CD.