Background

Racial disparities in Alzheimer’s disease and related dementias (ADRD) are well-documented, yet the contribution of neighborhood socioeconomic context to these disparities among breast cancer survivors remains unclear. The Index of Concentration at the Extremes (ICE) captures neighborhood-level deprivation and affluence, potentially mediating racial differences in ADRD diagnosis. Understanding the role of neighborhood-level factors may explain mechanisms behind these disparities.

Objective

To assess whether neighborhood-level socioeconomic conditions, measured by ICE, mediate the racial disparity in ADRD diagnosis among older female breast cancer survivors.

Methods

We analyzed SEER-Medicare linked data from 17,741 women aged 65 and older diagnosed with breast cancer (2007–2009) with up to 10 years of follow-up. ADRD diagnosis was identified through diagnostic codes. We conducted causal mediation analysis to estimate the average causal mediation effect (ACME), total effect, and proportion mediated by ICE on the association between race (Black vs. White) and ADRD diagnosis, adjusting for age, comorbidities using the Charlson Comorbidity Index (CCI), treatment type, and neighborhood -level poverty indicator.

Results

Race was significantly associated with ADRD diagnosis (total effect estimate = 0.052, 95% CI 0.028–0.077, p < 0.001). ICE significantly mediated this association, with an ACME of 0.049 (95% CI 0.035–0.063, p < 0.001), explaining approximately 93% of the total effect. This strongly suggests that neighborhood-level deprivation/advantage (ICE) explains most of the racial disparity in ADRD diagnoses in the dataset, after adjusting for age, neighborhood-level poverty indicator, treatment type, and CCI. The mediation findings remained robust in sensitivity analyses adjusting for additional covariates.

Conclusion

Neighborhood-level deprivation, as captured by ICE, substantially mediates racial disparities in ADRD diagnosis among breast cancer survivors, highlighting the critical role of social determinants and structural inequities on cognitive health outcomes. These findings suggest that beyond biological factors, such as hormone-modulating therapy-related cognitive effects, social context profoundly shapes racial disparities in cognitive health outcomes. This study shows the importance of neighborhood socioeconomic context in understanding racial disparities in ADRD diagnosis among breast cancer survivors. Further analyses incorporating additional covariates and stratified mediation will clarify the pathways influencing these disparities. Targeted interventions addressing neighborhood disadvantage may be essential for advancing equity in dementia prevention and care.