Child sex moderates the relationship between cortisol stress reactivity and symptoms over time.

BACKGROUND: Past work suggests that individual differences in stress reactivity have implications for the development of psychopathology; in particular, females' stress reactivity appears more closely tied to internalizing symptoms than males' reactivity. Conversely, males who are under-reactive to threat may be at risk for externalizing problems. However, little is known about when such differences may emerge, although this knowledge could have implications for early prevention.

METHODS: Cortisol reactivity to a laboratory stressor was assessed in 409 three-year-old children (201 boys), along with parent-reported children's internalizing (anxiety and depression) and externalizing (oppositional-defiant and attention problems and hyperactivity) symptoms. Parent-reported symptoms were re-collected at child ages 5 (N = 379) and 8 (N = 364). Multilevel modelling was used to investigate whether the relationship between cortisol reactivity and symptoms differed between boys and girls over time.

RESULTS: Girls with lower cortisol reactivity showed a negative association between depressive symptoms and time, while girls with higher reactivity showed no such association. No interaction between sex and cortisol reactivity was found for anxious symptoms. Boys with higher cortisol reactivity showed a negative association between symptoms and time, while boys with lower cortisol reactivity showed no such association. Time and ADHD symptoms were unrelated for boys, regardless of their cortisol reactivity.

CONCLUSIONS: Findings suggest that the implications of stress reactivity indexed via cortisol vary for boys and girls, as well as for different symptom manifestations.