Neuroendocrine basis of affective behavior: what we can learn from differences in sex development (DSD).

Steroid hormones influence affective behavior and its underlying neural networks. However, distinguishing between organizational and activational hormonal effects, along with effects of socialization, remains challenging, limiting the understanding of the mechanisms underlying affective neurobehavioral differences. Individuals with differences in sex development (DSD), such as congenital adrenal hyperplasia (CAH) and complete androgen insensitivity syndrome (CAIS), offer a unique opportunity to examine how alterations in prenatal steroid hormone exposure have a role in shaping brain development and human behaviors. This review aims to examine how, and to what extent CAH and CAIS, can inform broader neuroendocrine mechanisms of affective behavior. It starts with an overview of experimental psychology and human imaging work on the role of steroid hormones in affective behavior, highlighting the main challenges in the field in human research, and the rationale for including CAH and CAIS. It then summarizes findings from behavioral studies, experimental psychology, and neuroimaging research in CAH and CAIS to discuss how this research contributes to the understanding of the organizational role of steroid hormones on affective outcomes. Although the current evidence is limited and heterogeneous, this review highlights the contribution of prenatal hormonal variability, particularly prenatal androgen exposure, in shaping affective behavior and underlying neural networks. It also highlights how steroid hormones, chromosomal sex, timing of hormonal exposure, developmental stage and psychosocial factors interact in influencing affective outcomes. Advancing this work through neuroimaging and standardized experimental paradigms has the potential to specify the mechanistic pathways through which steroid hormone variability influences behavior. This work can also inform targeted interventions and support emotional well-being and quality of life for individuals with CAH and CAIS.