Red Blood Cell Biomarker May Aid in Diagnosis of Early Alzheimer Disease

LOS ANGELES — The level of α-syn heteroaggregates in red blood cells (RBCs) may be a tool for the diagnostic work-up of early Alzheimer disease (AD), according to study results presented at the Annual Scientific Meeting of the Alzheimer’s Association International Conference 2019, held July 14-18 in Los Angeles, California.

The study included patients with early-stage AD with prodromal symptoms or dementia (n=39) and age-matched healthy controls (n=39). All patients with AD showed a typical hippocampal phenotype and received a biomarker-based diagnosis (low cerebrospinal fluid levels of Aβ peptide combined with high cerebrospinal fluid concentrations of total-tau and/or phospho-tau proteins; or a positivity to cerebral amyloid-PET scan). Researchers analyzed the levels of homo- and hetero-aggregates of α-syn, Aβ, and tau in red blood cells (RBCs).

Compared with healthy controls, patients with AD had lower concentrations of α-syn and its heterocomplexes in their RBCs.

Researchers found RBC α-syn/Aβ and RBC α-syn/tau heterodimers could differentiate patients with AD from healthy controls with fair accuracy (area under receiver operating characteristic 0.76 and 0.72, respectively). RBC α-syn concentration, however, was a poor differentiator (area under receiver operating characteristic 0.63).

In a subset of 32 patients with AD, the results indicated RBC Aβ and RBC α-syn/Aβ heterocomplex had a moderate correlation with CSF Aβ (ps=.435 and .368, respectively; P=.015 and .042).

“RBCs may represent interesting peripheral in vivo models of neurodegeneration since they [are] likely to be involved in the accumulation and clearance of the misfolded proteins,” the researchers wrote.

Reference

Baldacci F. Potential diagnostic value of red blood cells a-synuclein heteroaggregates in Alzheimer’s disease. Abstract presented at: The Alzheimer’s Association International Conference 2019; July 14-18, 2019; Los Angeles, California.