β-amyloid pathology is not associated with depression in a large community sample autopsy study.

Background: Depression has been associated with dementia. This study aimed to verify if β-amyloid Alzheimer's disease-type burden was associated with lifetime major depressive disorder (MDD) and with current depressive symptoms in a large population-based autopsy study.

Methods: We included 1013 deceased subjects submitted to autopsy (mean age=74.3±11.6 years, 49% men) in a community sample. β-amyloid burden was measured in all cases based on the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) criteria for presence and density of neuritic plaques. Lifetime MDD was defined when at least one previous episode according to the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders - DSM (SCID). Depressive symptoms and cognitive impairment were determined using the depression item of the Neuropsychiatric Inventory (D-NPI>0) and the Clinical Dementia Rating scale (CDR>0.5) respectively.

Results: Lifetime MDD, late life depression (LLD) and current depressive symptoms were associated with cognitive impairment (p<0.001). Additionally, neuritic plaques were associated with cognitive impairment (p<0.001). Moderate or frequent neurite plaque density was not associated with MDD, LLD or current depressive symptoms in multiple logistic models adjusted for age, gender, and cognitive impairment.

Limitations: In this cross-sectional study, all neuropsychiatric and cognitive assessment were based on informant-report of deceased participants.

Conclusions: Different clinical depictions of depression were associated with dementia in this large community sample of elderly individuals with multiethnic backgrounds. Notwithstanding, they were unrelated to β-amyloid pathology in the brain areas studied. The link between depression and dementia might be complex and determined by multiple factors.