Cortisol and externalizing behavior in children and adolescents: Mixed meta‐analytic evidence for the inverse relation of basal cortisol and cortisol reactivity with externalizing behavior

An inverse relation between cortisol (re)activity and externalizing behavior has been hypothesized, but research findings seem equivocal. We tested this hypo(re)activity hypothesis in two meta‐analyses, one for basal cortisol ( k  = 72 studies, N  = 5,480) and one for cortisol reactivity to a stressor ( k  = 29 studies, N  = 2,601). No association was found between cortisol reactivity and externalizing behaviors ( r  = −.04, 95% CI = −.11, .02). However, the relation between basal cortisol and externalizing behavior was significant but small ( r  = −.05, 95% CI = −.10, −.002). The age of the children significantly moderated this relation: Externalizing behavior was associated with higher basal cortisol (hyperactivity) in preschoolers ( r  = .09, 95% CI = .002, .17), and with lower basal cortisol (hypoactivity) in elementary school‐aged children ( r  = −.14, 95% CI = −.19, −.08). There was no significant relation between cortisol and externalizing behavior in adolescents. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 50: 427–450, 2008.