Exploring the link between mood disorders and Alzheimer’s disease in the Australian Imaging, Biomarker & Lifestyle Study of Ageing (AIBL)

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AbstractBackgroundEpidemiological studies have demonstrated a positive association between mood disorders (anxiety and depression) and mild cognitive impairment (MC)/ Alzheimer’s disease (AD). However, the relationship between anxiety/depression and the progression of cognitive decline (PCD, i.e. cognitively unimpaired [CU] to MCI, and MCI to AD) in AD is not clearly understood.MethodA total of 2129 AIBL participants with data collected at 10 longitudinal timepoints were included in this study. The logistic regression model was employed to calculate the crude and adjusted odds ratios (OR), to assess the association between the anxiety/depression and MCI/AD. To determine the correlation between anxiety/depression and PCD, only participants who had anxiety/depression diagnosed prior to PCD was included for analysis. Potential confounders (smoking, alcohol, marital status, education, or sex) were adjusted for in the analysis.ResultAfter adjusting for all potential confounders, anxiety and depression were associated with an increased risk of MCI (anxiety OR:1.54, 95% confidence interval (CI): [1.00 ‐ 2.37], p = 0.049 / depression OR: 1.94, 95%CI: [1.30 ‐ 2.92], p = 0.001) or AD (anxiety OR: 2.43, 95%CI: [1.74 ‐ 3.39], p < 0.001 / depression OR: 2.27, 95%CI: [1.63 ‐ 3.16], p < 0.001). Both anxiety and depression were positively associated with a higher risk of progression from CU to MCI, though not statistically significant. After adjusting for all potential confounders, anxiety showed a high positive association with the progression from CU to AD (OR:2.25, 95%CI:[1.12 ‐ 4.53], p = 0.023) and MCI to AD (OR: 1.93, 95%CI: [1.15 ‐ 3.24], p = 0.013). Participants with anxiety also formed 1.53‐fold increased odds of PCD compared to those without anxiety. Similar calculations were performed for depression, but all associations observed in each condition were not statistically significant.ConclusionIn AIBL, we demonstrated a positive association between anxiety/depression and MCI/AD. Interestingly, anxiety but not depression was found to be a risk factor for PCD.