Depressive Symptoms Are Not Associated with Predementia Cerebrospinal Fluid Amyloid Pathology.

Introduction: Depressive symptoms are associated with Alzheimer's disease (AD), but their neurobiological and neuropsychological correlates remain poorly understood. We investigate if depressive symptoms are associated with amyloid (Aß) pathology and cognition in predementia AD. Methods: We included subjective cognitive decline (SCD, n = 160) and mild cognitive impairment (MCI, n = 192) from the dementia disease initiation cohort. Depressive symptoms were assessed using the Geriatric Depression Scale (GDS-15). Aß pathology was determined using cerebrospinal fluid (CSF) Aß42/40 ratio. Associations between depressive symptoms and cognition were assessed with logistic regression. Results: Only the Aß negative MCI group (MCI-Aß-) was associated with depressive symptoms (odds ratio [OR] = 2.65, p = 0.005). Depressive symptoms were associated with worse memory in MCI-Aß- (OR = 0.94, p = 0.039), but with better performance in MCI-Aß+ (OR = 1.103, p = 0.001). Conclusion: Our results suggest that depressive symptoms in MCI are neither associated with Aß pathology, nor AD-associated memory impairment. However, memory impairment in non-AD MCI may relate to depressive symptoms.

In Brief Neuropsychological Assessment, Amnestic Mild Cognitive Impairment (MCI) Is associated with Cerebrospinal Fluid Biomarkers for Cognitive Decline in Contrast to the Prevailing NIA-AA MCI Criterion.

BACKGROUND: In the care of persons with cognitive problems, it is important to use a valid mild cognitive impairment (MCI) criterion that discriminates well between normal and pathological aging. OBJECTIVE: To find the brief neuropsychological screening criterion that best correlates with cerebrospinal fluid (CSF) biomarkers for cognitive decline and dementia in persons seeking help for cognitive problems. METHODS: 452 consecutively recruited patients (age 40-80 years) from memory-clinics in the Norwegian national multicentre longitudinal study Dementia Disease Initiation were included. CSF data as well as full data from brief neuropsychological screening were available for all patients. RESULTS: Amnestic MCI, including at least one memory test below T-score 40, outperformed the conventional US National Institute on Aging-Alzheimer's Association (NIA-AA) MCI criterion. Only amnestic MCI was significantly associated with biomarker pattern of NIA-AA stage 2 (low CSF Aß42 concentrations and elevated tau) in multivariate regression analysis. CONCLUSIONS: The finding that amnestic MCI based on brief neuropsychological assessment is significantly associated with CSF biomarkers for cognitive decline and Alzheimer's disease is in accordance with longitudinal studies that find memory impairment; both in itself and especially in combination with other cognitive deficit to constitute a risk factor for subsequent cognitive decline and dementia. The prevalence of pathological biomarkers for Alzheimer's disease is common in the elderly and the clinical significance of present findings depend on longitudinal validation.