Trajectory of depressive symptoms prior to dementia diagnosis

Abstract

AbstractBackgroundDepression has been repeatedly linked to increased risk for dementia. While there is some research to suggest that an individual’s trajectory of depression symptoms over time may inform dementia risk above and beyond depression symptoms at a single time point, this has yet to be demonstrated in a dataset specifically designed to capture longitudinal brain aging and dementia outcomes.MethodA cohort study of 4,171 community‐dwelling older adults (65+ years) who were enrolled in the Adult Changes in Thought (ACT) study. Participants were initially non‐demented at baseline, and underwent biannual assessment of cognitive status (Cognitive Abilities Screening Instrument, diagnostic consensus) and self‐reported depression symptoms (via 20‐item Centers for Epidemiological Studies‐Depression [CESD]) for up to 24 years. We used Item Response Theory (CESD‐IRT) scores to address limited sensitivity to lower depressive symptom level in the general population and nonlinear measurement properties of the CESD. Diagnosis of dementia was made at consensus meeting based on history and clinical examination.ResultSample characteristics are summarized in Table 1. Linear mixed effects modeling, adjusted for covariates (age, sex, education, race), revealed that there was greater increase of depressive symptoms prior to diagnosis of dementia compared to those who did not receive diagnosis of dementia at end of study (p<.0001). This finding was consistent when depression symptom trajectories were estimated using CESD‐20 raw vs. CES‐IRT scores (Fig. 1 & 2, respectively). The difference in depression symptom trajectories by dementia outcome did not differ as a function of sex. Significant differences (p<0.001) in mean depression symptom total scores were observed by dementia outcome as early as 10 years prior to diagnosis/censoring for both the CESD‐20 raw score (1.0 ± 0.2) and the CESD‐IRT scores (0.16 ± 0.03).ConclusionThe pattern of increasing depression symptoms many years prior to dementia diagnosis reinforces the notion that the association between depressive symptoms and dementia in older adults may be primarily due to a shared common cause, or that depressive symptoms represent an early sign of dementia in the preclinical phase. Changes in specific depressive symptoms prior to dementia diagnosis will also be examined.