Do Hormone Levels Influence Bullying during Childhood and Adolescence? A Systematic Review of the Literature

(1) Background: Bullying is one of the most common forms of aggressive behavior during childhood and adolescence. Some decades ago, researchers began exploring the basis of peer victimization from a biological perspective. Specifically, the Hypothalamic-Pituitary-Adrenal (HPA) and Hypothalamic-Pituitary-Gonadal (HPG) axes have been studied in relation to status-relevant behaviors, such as bullying. (2) Methods: We conducted a systematic review following the PRISMA guide and registered the review protocol at PROSPERO (CRD42023494738). We searched for relevant studies in PubMed, Psycinfo, Scopus, and Web of Science, and assessed them using the Robins E-tool. (3) Results: Our search yielded 152 studies, of which 33 were included in the review. These studies explored the association between testosterone and cortisol levels with bullying behavior, finding diverse results. Most of the studies were rated as having a low risk of bias. (4) Conclusions: This study not only enhances our understanding of bullying, but also provides guidance for the development of prevention and management programs for it. In the future, researchers should continue exploring the joint effects of different hormones on the HPA and HPG axis, using a broader set of biomarkers.