Assessment of Plasma Biomarkers by ImmunoMagnetic Reduction in Parkinson's Disease Dementia and Dementia with Lewy Bodies
Giovanni Malaty1, Lih Fen Lue2, Holly Shill3, Boris Decourt4, Marwan Sabbagh1
1Barrow Neurological Institute, 2Sun Health Research Institute, 3Barrow Neurology Clinics, 4Roseman University of Health Sciences
Objective:
To use ImmunoMagnetic Reduction (IMR) assay to assess the diagnostic utility of plasma Aβ42, total Tau (t-Tau), phosphorylated Tau-181 (p-Tau-181) and α-synuclein in identifying and differentiating cases of Parkinson's Disease Dementia (PDD) and Dementia with Lewy Bodies (DLB).
Background:
PDD and DLB represent pathological subtypes along a continuum of synucleinopathies. Clinical differentiation is ultimately based on arbitrary and subjectively-reported timing of cognitive and motor symptoms. Ancillary tests are invasive, costly, and exhibit suboptimal sensitivity and specificity. Developments in plasma biomarker assays have increased detection thresholds and provide the opportunity to reassess whether core PDD/DLB plasma biomarkers would be useful for diagnosis.
Design/Methods:
Plasma samples from 61 total subjects (37 normal controls (NC), 12 with PDD, 12 with DLB) and were sent for IMR assay to quantify α-synuclein, Aβ42, t-Tau, and p-Tau-181. To determine discrimination between NC, PDD, and DLB, receiver operating characteristic (ROC) curve analysis was used to obtain sensitivity, specificity, and area under curve (AUC).
Results:
Plasma p-tau levels were significantly higher in DLB compared to NC and PD (p<0.05). Plasma α-synuclein levels were significantly higher in PDD compared to DLB and NC. Plasma t-Tau and Aβ42 levels did not differ between NC, PDD and DLB subjects. When plasma biomarkers were combined, Aβ42 x t-Tau revealed no differences between DLB, PDD and NC. For the α-synuclein x p-Tau-181 combination, both PDD and DLB were greater than NC.
Conclusions:
Investigations into the discrimination of DLB vs. PDD are rare. In this pilot study, we show that IMR assays of plasma for α-synuclein, p-Tau-181, and Aβ42 x t-tau are useful in differentiating PDD from DLB, as well as NC. Thus, our data suggest clinical utility of these novel biomarker modalities and panels. Differentiating DLB from PDD could be consequential in clinical characterization. Future studies will aim to replicate our findings on larger group sizes.