Higher levels of PTSD symptoms are present among trauma-exposed females v. males in adulthood; however, much less is known about the emergence of this sex difference during development.

In a multi-study sample of 7–18-year-olds (n = 3397), we examined the effect of sex and age on the severity of PTSD symptoms after a single incident trauma at 1 month (T1), and on symptom change after a natural recovery period of 3 (T2) and 6 months (T3). PTSD scores were harmonised across measurement types, and linear regressions were used to determine sex and age effects, adjusting for study level variance and trauma type.

A sex × age interaction was observed at T1 (p < 0.001) demonstrating that older age was associated with greater PTSD symptom severity in females (β = 0.008, p = 0.047), but less severe symptoms in males (β = −0.011, p = 0.014). The same pattern was observed at T2 and T3, with sex differences beginning to emerge by age 12 years. PTSD symptoms decreased naturally by ~25% at T2 with little further improvement by T3. Further, females showed a greater reduction in symptoms at T3 than males, although the same effect was not observed at T2.

Sex differences in PTSD symptoms become apparent during adolescence, due to opposing changes in susceptibility occurring in females and males with age. Understanding the factors contributing to these findings is likely to provide wider insight into sex-specific psychological vulnerability to trauma-related psychopathology.

Cross-sectional evidence suggests females in late adolescence exhibit higher rates of post-traumatic stress symptoms (PTSS) than males and younger age groups. However, longitudinal evidence is limited, and underlying factors are not well understood. We investigated the emergence of sex differences in PTSS from childhood to adolescence in a large, longitudinal UK cohort, and tested whether these could be explained by overlap between PTSS and depressive symptoms, or onset of puberty.

Trauma exposure and PTSS were assessed at ages 8, 10, 13 (parent-report) and 15 (self-report) years in a sub-sample of 9966 children and adolescents from the ALSPAC cohort-study. Analyses of PTSS focused on those who reported potential trauma-exposure at each time-point (ranged from n = 654 at 15 years to n = 1231 at 10 years). Age at peak-height velocity (APHV) was used as an indicator of pubertal timing.

There was no evidence of sex differences in PTSS at ages 8 and 10, but females were more likely to show PTSS at ages 13 (OR 1.54, p = 0.002) and 15 (OR 2.04, p = .001), even once symptoms related to depression were excluded. We found little evidence that the emergence of sex differences was related to pubertal timing (as indexed by APHV).

Results indicate that females show higher levels of PTSS in adolescence but not during childhood. The emergence of this sex difference does not seem to be explained by overlap with depressive symptoms, while the influence of pubertal status requires further investigation.