Mental disorders and discrimination: a prospective cohort study of young twin pairs in Germany

Abstract

ABSTRACTBackgroundMental disorders and discrimination share common risk factors. The association between having a mental disorder and experiencing discrimination is well-known, but the extent to which familial factors, such as genetic and shared environmental factors, might confound this association, including gender differences in familial confounding, remains unexplored.AimsWe investigated potential unmeasured familial confounding in the relationship between mental disorders and discrimination.MethodWe examined 2,044 same-sex twin pairs aged 16–25 years from the German population-based study’TwinLife’. We used a matched design and random-effects regression applied to within-individual and within-and-between pair models for the association between mental disorder and discrimination, and used likelihood ratio tests (LRTs) to compare these models. Multivariable models were adjusted for body-mass-index, educational attainment, and global life satisfaction.ResultsMental disorder and discrimination were associated in the adjusted within-individual model (adjusted odds ratio=2.19, 95% Confidence Interval:1.42–3.39,P<0.001). However, the within-and-between pair model showed that this association was explained by the within-pair mean (aOR=4.24, 95%CI:2.17–8.29,P<0.001) and not the within-pair difference (aOR=1.26, 95%CI:0.70–2.28,P=0.4) of mental disorder. Therefore, this association was mostly explained by familial confounding, which is also supported by the LRTs for the unadjusted and adjusted models (P<0.001 andP=0.03, respectively). This familial confounding was more prominent for males than females.ConclusionsOur findings show that the association between mental disorder and discrimination is almost fully explained by unmeasured familial factors. Incorporating family members in interventions targeted at ameliorating mental ill-health and experiences of discrimination among adolescents may improve efficacy.