Increased albumin CSF/serum ratio in dementia with Lewy bodies.
Alterations in the CSF/serum albumin ratio (Qalb) is currently recognized as one of the most reliable markers of blood-brain barrier impairment and blood-CSF barrier permeability, but its potential role as a biomarker in the differential diagnosis of neurological diseases has been poorly analysed. We evaluated Qalb and core CSF biomarkers (Tau, p-Tau and Aβ42) in a large patient population of neurological and neurodegenerative cases. Diagnostic test evaluation was assessed by ROC-AUC analysis. In the differential diagnostic analysis, increased Qalb was found in dementia with Lewy bodies (DLB) patients compared to other diseases, either individually or stratified in non-dementia and dementia groups. When clinical groups were analysed individually and compared to controls, Qalb was also increased in stroke and Parkinson's disease dementia (PDD) cases, but not in Parkinson's disease (PD). Qalb in DLB cases correlate with CSF Aβ42 levels but not with Tau and p-Tau levels. Due to the lower CSF Aβ42 levels in DLB compared to PD and PDD, the potential clinical applicability of Qalb with respect to the DLB diagnosis is increased in combination with CSF Aβ42 analysis. The present study demonstrates increased Qalb in synucleinopathies associated with dementia revealing a potential new clinical approach for the differential diagnosis of DLB.