Longitudinal Association of Dementia and Depression

Abstract

Objectives: Depression is an important precursor to dementia, but less is known about the role dementia plays in altering the course of depression. We examined whether depression prevalence, incidence, and severity are higher in those with dementia versus those with mild cognitive impairment (MCI), or normal cognition.

Design: Prospective cohort study using the longitudinal Uniform Data Set of the National Alzheimer's Coordinating Center (2005-2013).

Setting: 34 Alzheimer Disease research centers.

Participants: 27,776 subjects with dementia, MCI, or normal cognition.

Measurements: Depression status was determined by a clinical diagnosis of depression within the prior 2 years and by a Geriatric Depression Scale-Short Form score >5.

Results: Rates of depression were significantly higher in subjects with MCI and dementia compared with those with normal cognition at index visit. Controlling for demographics and common chronic conditions, logistic regression analysis revealed elevated depression in those with MCI (OR: 2.40 [95% CI: 2.25, 2.56]) or dementia (OR: 2.64 [95% CI: 2.43, 2.86]) relative to those with normal cognition. In the subjects without depression at the index visit (N = 18,842), those with MCI and dementia had higher probabilities of depression diagnosis 2 years post index visit than those with normal cognition: MCI = 21.7%, dementia = 24.7%, normal cognition = 10.5%.

Conclusion: MCI and dementia were associated with significantly higher rates of depression in concurrent as well as prospective analyses. These findings suggest that efforts to effectively engage and treat older adults with dementia will need also to address co-occurring depression.

Keywords: Alzheimer disease; Dementia; depression.