Background International evidence documents that experiencing racial discrimination is associated with poor physical and mental health among ethnic minority people, but there is a gap in our understanding of how the accumulation of exposure to racial discrimination, over time and across domains of exposure, is associated with increased morbidity. In this study we examined the longitudinal association between cumulative exposure to racial discrimination and changes in the mental health of ethnic minority people in the UK.

Methods We apply linear regression models to data from four waves (2009 to 2013) of the United Kingdom (UK) Household Longitudinal Study. Models adjusted for sex, age, household income, and previous psychological distress, which we measured with the mental component of the Short-Form 12 Health Survey (SF-12).

Results Ethnic minority people who reported exposure to racial discrimination at one time point had SF-12 scores 1.93 (CI = −3.31, −0.56) points lower than those who reported no exposure to racial discrimination, whereas those who had been exposed to two or more domains of racial discrimination, at two different time points, had SF-12 scores 8.26 (CI = −13.33, −3.18) points lower than those who had reported no experiences of racial discrimination. Controlling for racial discrimination and other socioeconomic factors reduced ethnic inequalities in mental health.

Conclusion Cumulative exposure to racial discrimination has incremental negative long-term effects on the mental health of ethnic minority people in the UK. Studies that examine exposure of racial discrimination at one point in time underestimate the contribution of racism on health.