Editorial: The Importance of Considering Multiple Factors Simultaneously to Advance Psychopathology Research.

Recent advances in scientific techniques, particularly in psychoneuroendocrinology and functional neuroimaging, have made it clear that clinically significant antisocial behavior, such as that seen in conduct disorder, cannot be understood without reference to multiple biological systems. However, the additional complexity arising from the interaction between the multiple biological systems implicated in conduct disorder has not typically been reflected in the complexity of experimental designs. Most often, studies examine only one system or subsystem at a time. Furthermore, the majority of studies of conduct disorder have not included female participants, have included few female participants, and/or have not explicitly considered biological sex in analytic strategies. Particularly in the context of endocrinological functioning, biological sex is an important but understudied biological variable. Greater complexity in experimental design, incorporating data from different biological systems, and factoring in important variables such as sex will be needed moving forward to adequately model data from all of the relevant levels of analysis. This is true with respect not just to conduct disorder but to all psychopathology. The paper by Bernhard et al published in this issue is an excellent example of the types of studies that are required to grapple with the complexity of any psychiatric illness. Their study is notable for its examination of multiple endocrine systems simultaneously and for adequately incorporating biological sex as a variable into the study.