Exploring the causal role of intimate partner violence and abuse on depressive symptoms in young adults: a population-based cohort study.

Background: Previous studies have shown an association between experience of intimate partner violence and abuse (IPVA) and depression. Whether this is a causal relationship or explained by prior vulnerability that influences the risk of both IPVA and depression is not known.

Methods: We analysed data from the Avon Longitudinal Study of Parents and Children prospective cohort (N = 1764 women, 1028 men). To assess the causal association between IPVA at 18-21 years old and logged depressive symptom scores at age 23, we used (i) multivariable linear regression, (ii) inverse probability of treatment weighting (IPTW), and (iii) difference-in-difference (DiD) analysis, which compared the mean change in logged depressive symptom scores between ages 16 and 23 between those who experienced IPVA and those who did not.

Results: Women who experienced IPVA had on average 26% higher depressive symptom scores after adjustment for measured confounders (ratio of geometric means 1.26, 95% CI 1.13 to 1.40). In men, the difference was 5% (ratio of geometric means 1.05, 95% CI 0.92 to 1.21). Results from IPTW analysis were similar. In the DiD analysis, there was no evidence that being exposed to IPVA affected the change in depressive symptom scores over time compared to being in the non-exposed group for either women (difference-in-differences 1%, -12 to 16%) or men (-1%, -19 to 20%).

Conclusions: Multivariable linear regression and IPTW suggested an association between IPVA and higher depressive symptom score in women but not men, but DiD analysis indicated a null effect in both women and men. This suggests the causal origins of higher depressive symptoms in this young adult population are likely to reflect prior vulnerability that leads to both higher depressive symptoms and increased risk of IPVA exposure.