FRIDAY, Jan. 13, 2023 (HealthDay News) — Plasma phosphorylated tau (P-tau181), neurofilament light chain (NfL), and glial fibrillary acidic protein (GFAP) seem feasible as plasma biomarkers for detecting Alzheimer disease in presymptomatic individuals, according to a study published online Jan. 11 in Brain.

Charlotte Johansson, from Karolinska Institutet in Stockholm, and colleagues explored the timing and performance of plasma biomarkers in mutation carriers versus noncarriers of autosomal dominant Alzheimer disease. Samples were obtained from 33 mutation carriers and 42 noncarriers. P-tau181, total tau (T-tau), NfL, and GFAP concentrations were measured and correlated with Alzheimer disease core biomarkers in the cerebrospinal fluid (CSF).

The researchers found that plasma P-tau181, NfL, and GFAP concentrations were higher in mutation carriers versus noncarriers in longitudinal analyses. This change was seen in the presymptomatic phase, and was first identified as an increase in GFAP about 10 years prior to estimated onset of symptoms, followed by increases in P-tau181 and NfL levels closer to expected onset. There were correlations seen for plasma P-tau181 levels with Ptau-181 and T-tau levels in the CSF.

“Our results suggest that plasma GFAP is more strongly correlated to the early pathological accumulation of amyloidβ in CNS rather than to the downstream pathological accumulation of tau,” the authors write. “These results remain to be replicated in larger cohorts and further studies are needed to investigate whether plasma GFAP also correlates to or can predict astrocytic activation.”

Several authors disclosed financial ties to the biotechnology and pharmaceutical industry.

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