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

## TL;DR

This study shows that mental disorders and discrimination often occur together in the same families, suggesting that family-based interventions could be more effective.

## Contribution

The study is the first to examine the mental disorder-discrimination link while accounting for shared familial factors.

## Key findings

- Mental disorder and discrimination cluster within families, not just individuals.
- Familial confounding explains much of the association between mental disorder and discrimination.
- Family-based healthcare models may improve outcomes for those affected by discrimination.

## Abstract

Mental disorders and perceived 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 sex differences in familial confounding, remains unexplored.

We investigated potential unmeasured familial confounding in the association between mental disorders and perceived discrimination using a matched twin study design.

We examined data from 2044 same-sex twin pairs (n = 4088) aged 16–25 years from the German population-based study ‘TwinLife'. We applied random-effects logistic regression to within-individual and within-and-between pair models of the association between mental disorder and perceived discrimination, and used likelihood ratio tests (LRTs) to compare these models. Multivariable models were adjusted for body mass index, educational attainment, and life satisfaction.

There were 322 (8.1%) participants with a diagnosed mental disorder, and 15% (n = 604) of the cohort reported having experienced discrimination in the previous 12 months. Mental 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 and P = 0.03, respectively). This familial confounding was more prominent for males than females.

Our findings show that the association between mental disorder and discrimination is at least partially explained by unmeasured familial factors. Designing family-based healthcare models and incorporating family members in interventions targeted at ameliorating mental ill-health and experiences of discrimination among adolescents may improve efficacy.

•For the first time, we investigated the association between mental disorder and discrimination while accounting for shared familial factors.•Mental disorder and discrimination tends to cluster among people of the same familial background.•Family-based interventions and models of mental healthcare are more likely to be effective for families affected by racism and discrimination.

For the first time, we investigated the association between mental disorder and discrimination while accounting for shared familial factors.

Mental disorder and discrimination tends to cluster among people of the same familial background.

Family-based interventions and models of mental healthcare are more likely to be effective for families affected by racism and discrimination.