Cerebrospinal Fluid Alzheimer Markers in Depressed Elderly Subjects with and without Alzheimer's Disease

BACKGROUND: The aim of this study was to explore the relationship between cerebrospinal fluid Alzheimer's disease (AD) markers and depression in elderly people. METHOD: We included subjects with AD as well as persons with subjective cognitive impairment and normal cognition. Depression was assessed with the Cornell Scale for Depression in Dementia, and a cut-off score of >6 was used to define depression. Cerebrospinal fluid was analyzed using commercially available assays for β-amyloid 1–42, total tau, and phosphorylated tau 181. RESULTS: A total of 183 participants (66.7% female) were included (92 with AD and 91 with subjective cognitive impairment), with a mean age (±SD) of 67.6 ± 7.4 years, a Mini-Mental State Examination score of 26.0 ± 4.0, and a median Cornell Scale for Depression in Dementia score of 5 (range 0–19). Depression scores were not associated with higher phosphorylated tau 181 and total tau or reduced β-amyloid 1–42 in AD or non-demented subjects. CONCLUSIONS: These results suggest that AD pathology does not contribute to depression, indicating that other factors may be more important. Further studies of the aetiology of depression in elderly people with and without AD are warranted.