Diagnostic value of CSF chromogranin A to discriminate between Alzheimer's disease and dementia with Lewy bodies.

BACKGROUND: Chromogranin A (CgA) seems to be involved in the pathophysiology of different neurodegenerative pathologies such as Alzheimer's disease (AD) and dementia with Lewy Bodies (DLB). CgA is present in the aggregates of amyloid plaques and in Lewy bodies but CgA also has a function in neuroinflammatory processes via microglia. Our objective was to determine if there is a difference in the CgA concentration in the cerebrospinal fluid (CSF) of AD and DLB patients and whether the CgA concentration can discriminate between the two diseases. METHODS: Using the previously described AlphaLewyMA cohort, we included 117 patients with a CSF CgA assay: 15 control subjects (CS group), 64 DLB patients, 17 AD patients and 21 patients with both AD and probable DLB criteria (AD/DLB group). CgA concentration was assessed using the MSD platform. RESULTS: CSF CgA was increased in the AD and AD/DLB groups compared with the DLB group (p = 0.0006 between AD and DLB, p = 0.0013 between AD/DLB and DLB). No significant difference in CgA concentration was found between DLB and CS. ROC curve analysis showed an area under the curve of 0.791 between AD and DLB. CgA concentrations were correlated with t-Tau and P-Tau regardless of the pathology (for Tau: p = 0.022 for AD; p < 0.0001 for DLB; p = 0.004 for AD/DLB; for P-Tau: p = 0.032 for AD; p < 0.0001 for DLB; p = 0.0009 for AD/DLB). Aß42 was positively correlated with CgA in the DLB group but not in the AD and AD/DLB groups (for DLB: p < 0.0001; for AD: p = 0.57; for AD/DLB: p = 0.58). CONCLUSIONS: CSF CgA concentrations are increased in AD but not in DLB and correlate with P-Tau and Tau whatever the disease. These results suggest a link between tauopathy/neurodegeneration and CgA.

Differential diagnostic value of total alpha-synuclein assay in the cerebrospinal fluid between Alzheimer's disease and dementia with Lewy bodies from the prodromal stage.

BACKGROUND: Several studies have investigated the value of alpha-synuclein assay in the cerebrospinal fluid (CSF) of Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) patients in the differential diagnosis of these two pathologies. However, very few studies have focused on this assay in AD and DLB patients at the MCI stage. METHODS: All patients were enrolled under a hospital clinical research protocol from the tertiary Memory Clinic (CM2R) of Alsace, France, by an experienced team of clinicians. A total of 166 patients were included in this study: 21 control subjects (CS), 51 patients with DLB at the prodromal stage (pro-DLB), 16 patients with DLB at the demented stage (DLB-d), 33 AD patients at the prodromal stage (pro-AD), 32 AD patients at the demented stage (AD-d), and 13 patients with mixed pathology (AD+DLB). CSF levels of total alpha-synuclein were assessed using a commercial enzyme-linked immunosorbent assay (ELISA) for alpha-synuclein (AJ Roboscreen). Alzheimer's biomarkers (t-Tau, P-Tau, Aß42, and Aß40) were also measured. RESULTS: The alpha-synuclein assays showed a significant difference between the AD and DLB groups. Total alpha-synuclein levels were significantly higher in AD patients than in DLB patients. However, the ROC curves show a moderate discriminating power between AD and DLB (AUC = 0.78) which does not improve the discriminating power of the combination of Alzheimer biomarkers (AUC = 0.95 with or without alpha-synuclein). Interestingly, the levels appeared to be altered from the prodromal stage in both AD and DLB. CONCLUSIONS: The modification of total alpha-synuclein levels in the CSF of patients occurs early, from the prodromal stage. The adding of alpha-synuclein total to the combination of Alzheimer's biomarker does not improve the differential diagnosis between AD and DLB. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01876459 (AlphaLewyMa).