Anemia and Depression in Older Adults: A Longitudinal Cohort Study

Abstract

ObjectiveTo elucidate the relationship between anemia and depression in older adults. DesignSecondary analysis of a prospective longitudinal cohort study of healthy older adults. SettingCommunity settings in Australia and the United States of America. Participants19,111 community-dwelling adults with a mean age of 75 years. MeasurementsAnemia was classified according to the World Health Organization definition. Depressive symptoms were measured using the Center for Epidemiologic Studies Depression 10-item scale (CES-D-10), with a score ≥ 10 indicating depression. A range of potentially confounding factors, including important characteristics, concomitant medication, medical morbidities, physical function, and functional status were assessed. Depressive symptoms and hemoglobin levels were measured concurrently each year for up to 10 years (median 6 years). The association between anemia and depression was assessed using generalized estimating equations (GEE) with robust variance estimation to handle repeated measures clustered data. ResultsThe odds ratio (OR) for depression in individuals with anemia, adjusted for age, gender, ethnicity, living arrangements, education, smoking status, alcohol consumption, BMI, history of cancer, hypertension, chronic kidney disease, diabetes, gastro-oesophageal reflux disease, polypharmacy, antithrombotic use (including aspirin use), antidepressant use, and antipsychotic use, was 1.18 (95% CI 1.08–1.30). When further adjusted for grip strength, gait speed, and activities of daily living, the OR reduced to 0.94 (95% CI 0.79–1.13). ConclusionsAnemia was not independently associated with depression in older adults after adjusting for physical activity, functional status, and known comorbidities. Functional status may play a mediating role and should be explored further in mediation analysis. The lack of available data on ferritin, vitamin B12 and folate levels for all participants meant that the cause of anemia could not be inferred for all participants.