Depression and Dementia Risk: A Population-Based Cohort Study in Denmark (P2-6.008)

Abstract

<h3>Objective:</h3> Examine the relation between depression and incident dementia in Denmark. <h3>Background:</h3> Depressive symptoms often precede onset of dementia, but prior research reports diminished or null associations with increasing time since depression diagnosis. The absence of an association between remote depression diagnosis and incident dementia suggests depression is an early symptom rather than a cause of dementia. <h3>Design/Methods:</h3> This nationwide population-based cohort study leverages data collected routinely and prospectively from Danish population-based registries from 1978–2018. Individuals with depression ages ≥18 years were matched with members of the general population on sex, birth year, and date of depression diagnosis. Using Cox proportional hazards regression models, we estimated hazard ratios (HR) for the association between depression and dementia. To characterize the relationship between depression and dementia, all analyses were stratified by time elapsed between diagnoses (1–10 years; &gt;10–20 years; &gt;20–39 years). Because risk of depression and dementia may differ by age and sex, we conducted separate analyses for men and women and by age category. <h3>Results:</h3> Among 246,499 persons with depressive disorders and 1,190,302 matched persons, depression was associated with more than double the hazard of dementia (HR=2.43; 95% confidence interval [CI]: 2.37, 2.49). This HR was largest within the first 10 years after depression diagnosis (HR=2.60, 95% CI: 2.53, 2.68), but persisted &gt;10–20 years (HR=1.89, 95% CI: 1.79, 2.01) and &gt;20–39 years (HR=1.80, 95% CI: 1.59, 2.04). The association between depression and dementia was stronger among men (HR=3.02, 95% CI: 2.88, 3.16) than women (HR=2.22, 95% CI: 2.16, 2.29), and strongest among individuals diagnosed with depression between ages 18–44 (HR=3.09, 95% CI: 2.66, 3.60). <h3>Conclusions:</h3> This study demonstrates a robust association between incident depression and subsequent dementia when the diagnoses are separated by more than two decades, and thus suggests a role for depression as a major risk factor. <b>Disclosure:</b> Dr. Elser has nothing to disclose. Dr. Horvath-Puho has nothing to disclose. Dr. Gradus has nothing to disclose. Dr. Smith has nothing to disclose. Dr. Lash has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Amgen. Dr. Lash has received publishing royalties from a publication relating to health care. Maria Glymour has nothing to disclose. Prof. Soerensen has nothing to disclose. Dr. Henderson has stock in Abbott, Amgen, Roche. The institution of Dr. Henderson has received research support from NIH. The institution of Dr. Henderson has received research support from Health IQ. Dr. Henderson has received personal compensation in the range of $500-$4,999 for serving as a External advisory committee member, Alzheimer’s Disease Center with University of Kansas. Dr. Henderson has a non-compensated relationship as a adjunct (honorary) professor with Aarhus University that is relevant to AAN interests or activities.