Added diagnostic value of CSF biomarkers in differential dementia diagnosis

This study aimed to investigate whether cerebrospinal fluid (CSF) biomarkers could have helped the clinician in differential dementia diagnosis in case of clinically ambiguous diagnoses, as compared to autopsy-confirmed dementia diagnosis as gold standard. Twenty-two patients of our autopsy-confirmed dementia population totalling 157 patients had an ambiguous clinical diagnosis at CSF sampling and were included in statistical analysis. CSF levels of β-amyloid peptide (Aβ(1-42)), total tau protein (T-tau) and tau phosphorylated at threonine 181 (P-tau(181P)) were determined. A biomarker-based model was applied to discriminate between AD and NON-AD dementias. AD and NON-AD patients showed no significant differences in Aβ(1-42) and T-tau concentrations, whereas P-tau(181P) concentrations were significantly higher in AD compared to NON-AD patients. The biomarker-based diagnostic model correctly classified 18 of 22 (82%) patients with clinically ambiguous diagnoses. Using a biomarker-based model in patients with clinically ambiguous diagnoses, a correct diagnosis would have been established in the majority of autopsy-confirmed AD and NON-AD cases, indicating that biomarkers have an added diagnostic value in cases with ambiguous clinical diagnoses.