Longitudinal associations of depression and diabetes with Alzheimer’s disease and related dementias risk among American Indian and Alaska Native people

Abstract

AbstractBackgroundAlzheimer’s disease and related dementias (ADRD) research worldwide indicate that it is more common in indigenous than in non‐indigenous populations. The increased risk for ADRD among indigenous people may be partially due to the population’s high rates of depression and diabetes. Thus, we examined the relationship of depression and diabetes, alone and together, with incident ADRD in a large sample of American Indian and Alaska Native people (AI/ANs).MethodWe used data from the Indian Health Service (IHS) Improving Health Care Delivery Data Project with a sample of 65,801 AI/ANs aged ≥ 45 years. The IHS Data Project includes data for a purposeful sample of AI/ANs who lived in 15 IHS service units, which are IHS geographic classifications located throughout the United States. We used Cox proportional hazard models to estimate associations between ADRD risk and baseline depression and diabetes.ResultWe found that 2.3% of our sample received an ADRD diagnosis during FY2010‐13. Compared to persons with neither depression nor diabetes, unadjusted models indicated that those who had both depression and diabetes had twice the risk of developing ADRD (Hazard Ratio (HR) = 2.02, 95% CI = 1.72‐2.37). The unadjusted risk among those with depression only was 77% higher (HR = 1.77, 95% CI = 1.50‐2.08). Adjusted analyses showed that the HR for those with depression and diabetes was 1.82 (95% CI = 1.53‐2.16) and those with depression only had a hazard ratio of 1.70 (95% CI = 1.44‐2.00) for ADRD. The association between depression and diabetes and depression only with ADRD risk was stronger for persons aged 45 to 64 years compared to persons aged ≥ 65 years. In the adjusted models, we did not find a relationship between only having diabetes and ADRD risk.ConclusionOur findings suggest that depression by itself and depression with diabetes increases the risk of ADRD in AI/ANs aged ≥ 45 years. In the future, ensuring clinical and behavioral services for AI/ANs include regular mental health screening and depression treatment might help decrease ADRD risk. Such efforts may also focus on middle‐aged persons.