Linking GFAP Levels to Speech Anomalies in Acute Brain Injury: A Simulation Based Study

Background: Glial fibrillary acidic protein (GFAP) is a biomarker for intracerebral hemorrhage and traumatic brain injury, but its link to acute speech disruption is untested. Speech anomalies often emerge early after injury, enabling rapid triage. Methods: We simulated a cohort of 200 virtual patients stratified by lesion location, onset time, and severity. GFAP kinetics followed published trajectories; speech anomalies were generated from lesion-specific neurophysiological mappings. Ensemble machine-learning models used GFAP, speech, and lesion features; robustness was tested under noise, delays, and label dropout. Causal inference (inverse probability of treatment weighting and targeted maximum likelihood estimation) estimated directional associations between GFAP elevation and speech severity. Findings: GFAP correlated with simulated speech anomaly severity (Spearman rho = 0.48), strongest for cortical lesions (rho = 0.55). Voice anomalies preceded detectable GFAP rise by a median of 42 minutes in cortical injury. Classifier area under the curve values were 0.74 (GFAP only), 0.78 (voice only), and 0.86 for the fused multimodal model, which showed higher sensitivity in mild or ambiguous cases. Causal estimates indicated higher GFAP increased the modeled probability of moderate-to-severe speech anomalies by 32 to 35 percent, independent of lesion site and onset time. Conclusion: These results support a link between GFAP elevation and speech anomalies in acute brain injury and suggest integrated biochemical-voice diagnostics could improve early triage, especially for cortical injury. Findings are simulation-based and require validation in prospective clinical studies with synchronized GFAP assays and speech recordings.