The impact of sexual violence in mid-adolescence on mental health: a UK population-based longitudinal study.

Background: A large gender gap appears in internalising mental health conditions during adolescence, with higher rates in girls than boys. There is little high-quality longitudinal population-based research investigating the role of sexual violence experiences, which are disproportionately experienced by girls. We aimed to estimate the effects of sexual violence experienced in mid-adolescence on mental health outcomes.

Methods: In this study, we used data from the longitudinal UK Millennium Cohort Study, a large nationally representative cohort of children born in the UK in 2000-02, for participants with information available at age 17 years on sexual violence in the past year (eg, sexual assault or unwelcome sexual approach), mental health outcomes (eg, completion of the Kessler Psychological Distress K6 scale in the past 30 days, self-harm in the past year, and lifetime attempted suicide). Multivariable confounder adjusted regressions and propensity matching approaches were used, and population attributable fractions (PAFs) were calculated.

Findings: We included 5119 girls and 4852 boys (8063 [80·8%] of whom were White) in the full analysis sample. In the fully adjusted model, compared with no sexual violence, sexual violence was associated with greater mean psychological distress in girls (mean difference 2·09 [95% CI 1·51-2·68]) and boys (2·56 [1·59-3·53]), higher risk of high psychological distress in girls (risk ratio [RR] 1·65 [95% CI 1·37-2·00]) and boys (1·55 [1·00-2·40]), higher risk of self-harm in girls (RR 1·79 [1·52-2·10]) and boys (RR 2·16 [1·63-2·84]), and higher risk of attempted suicide in girls (RR 1·75 [1·26-2·41]) and boys (RR 2·73 [1·59-4·67]). PAF estimates suggest that, in a hypothetical scenario with no sexual violence, the prevalence of adverse mental health outcomes at age 17 years would be 3·7-10·5% lower in boys and 14·0-18·7% lower in girls than the prevalence in this cohort.

Interpretation: Reductions in sexual violence via policy and societal changes would benefit the mental health of adolescents and might contribute to narrowing the gender gap in internalising mental ill health. Clinicians and others working to support adolescents should be aware that sexual violence has a widespread, gendered nature and an impact on mental health.

Funding: UK Medical Research Council.