Relationship between Depressive Symptoms and Cognitive Decline

Objectives: Depression and cognitive decline have a complex relationship. The purpose of our study was to determine if depression, or specific symptoms of depression, influences the rate of cognitive decline. Methods: We conducted linear regression analysis to determine if baseline depression or depressive symptoms influenced the rate of age-related cognitive decline. Data analyzed were from 634 male and 934 female elderly white, non-Hispanic participants in the Texas Alzheimer’s Research and Care Consortium. Participants included cognitively normal controls (733), subjects with mild cognitive impairment (243) and subjects with Alzheimer’s disease (592). Baseline depression was estimated using Geriatric Depression Scale (GDS30) scores. Baseline depressive symptoms included apathy and agitation, as measured in the Neuropsychiatric Inventory Questionnaire (NPI-Q). Cognitive decline was measured by a change in Clinical Dementia Rating (CDR) scores between visits 1 and 3. In these analyses we stratified based on gender and adjusted for age at first visit and education. Results: We found that baseline overall depression (GDS30) was not significantly related to cognitive decline. Specific depressive symptoms were significantly related to cognitive decline, but there were different effects in men and women. Apathy was correlated with increased cognitive decline in men only (p Conclusions: Depressive symptoms appear to increase the rate of cognitive decline and may be early signs for neurodegeneration. These symptoms may also be important targets for therapeutics designed to treat, or slow the progression of Alzheimer’s disease. However, the relationship is not simple, as indicated by the divergent results observed in males and females. Further research in this area is warranted; while there are currently no proven treatments for Alzheimer’s disease, depression and depressive symptoms are therapeutically modifiable.