Cognitive Impairment and Its Consequences on Health among Breast Cancer Patients

Abstract

Objectives: The purpose of this study was to 1) examine the impact of preexisting cognitive impairment on survival and chronic medication adherence among older adults with breast cancer, 2) examine the association between chemotherapy and cognitive impairment among older adults with breast cancer, and 3) examine the association between antidepressants and cognitive impairment among older adults with breast cancer. Methods: This retrospective cohort study of female patients aged 67 years or older diagnosed with breast cancer was performed using the Surveillance, Epidemiology, and End Results-Medicare Linked Database of the National Cancer Institute. We examined the risk of mortality from cancer and non-cancer causes in patients with and without a history of cognitive impairment (aim 1). In addition, we examined if chronic medication adherence differ between these groups of patients and if medication adherence mediates or moderates the association between cognitive impairment and non-cancer mortality (aim 1). Furthermore, we examined if chemotherapy (aim 2) or antidepressants (aim 3) were associated with an increased risk of cognitive impairment after breast cancer diagnosis. Difference-in-differences, logistic regression, and Cox proportional hazards regression models were used to assess the outcomes of interest for each aim. Results: Mortality from cancer-specific and non-cancer causes as well as all-cause mortality was markedly higher in patients with cognitive impairment than in those without cognitive impairment. Both groups showed low adherence levels to chronic medication before and after the breast cancer diagnosis, but the differences between the groups were not significant. Further analysis did not show that medication adherence mediates or moderates the relationship between cognitive impairment and non-cancer mortality. Chemotherapy was not associated with a statistically significant risk of cognitive impairment. However, Antidepressant use was associated with a significantly increased risk of cognitive impairment. Conclusion: The results of this study indicate that female patients aged 67 or older with cognitive impairment and a breast cancer diagnosis have a heightened risk of cancer-specific and non-cancer mortality. Our findings did not indicate that medication adherence plays a role in the association between a history of cognitive impairment and mortality. In addition, our findings suggest that there was no increased risk of developing cognitive impairment among older patients with breast cancer after they were exposed to chemotherapy. However, we found that antidepressant use in older adults with breast cancer was associated with a higher risk of cognitive impairment.