Background: The literature suggests an association between depression and mild cognitive impairment (MCI) and dementia, but not all studies have examined this association with regard to MCI subtypes reflecting different dementia etiologies.
Objective: To examine if there is a cross-sectional relationship of depression and MCI and to examine if the relationship differs depending on the type of depression (currently elevated depressive symptoms or a positive history of lifetime depression or both) and on the MCI subtype (amnestic versus non-amnestic MCI (aMCI/naMCI)).
Methods: From the second examination of the population-based Heinz Nixdorf Recall study (50% men, 50–80 years), 583 participants with MCI (aMCI n=304; naMCI n=279) and 1,446 cognitively normal participants were included in the analyses. Currently elevated depressive symptoms were assessed using the Center for Epidemiologic Studies Depression Scale (CES-D; score ≥18). Furthermore, participants were asked if they have ever received a previous diagnosis of depression. Log-Poisson regression models (adjusted for sociodemographic/cardiovascular risk factors) were calculated to determine the association of MCI and its subtypes with all depression variables.
Results: The fully adjusted prevalence rate ratios for MCI, aMCI, and naMCI in depressed versus non-depressed participants were 2.06 (95% confidence interval, 1.60–2.64), 3.06 (2.21–4.23), and 1.93 (1.46–2.57). A positive history of lifetime depression without current depressive symptoms was solely associated with naMCI (1.31 (0.99–1.73)).
Conclusion: These results suggest that the relationship of depression/depressive symptoms and MCI might differ depending on the timing of depression and on the MCI subtype. Our longitudinal follow-up will allow us to further elucidate this relationship.