Hyperventilation Unmasks Convergent Aperiodic EEG Vulnerability in Seizure Disorder and Schizophrenia

Electroencephalographic (EEG) reactivity to hyperventilation probes neural responsiveness to metabolic challenge, yet no systematic study has characterized its lifespan variation. Conventional analysis further restricts inference to oscillatory dynamics, overlooking aperiodic components that reflect systems-level properties of neural population activity. We constructed brain lobe-specific lifespan reference charts for HV reactivity across oscillatory (alpha and beta power and frequency) and aperiodic (1/f slope and offset) parameters in 14,905 outpatient recordings (ages 1-88), then quantified normative deviations in seizure disorder (N=115) and schizophrenia (N=154), two conditions with mechanistically opposing excitatory-inhibitory dysfunction. Adolescence (-age 12) marked a critical inflection point: oscillatory power reactivity converged toward zero while aperiodic parameters reached peak dynamic range. As expected from opposing pathophysiology, seizure disorder and schizophrenia showed divergent oscillatory signatures, though effect sizes were modest (Cohens d < 0.2). Both disorders, however, converged on hyporeactive aperiodic offset with large effect sizes (Cohens d > 0.5 across all lobes), indicating shared impairment in modulating broadband population activity under metabolic stress. These findings establish the first lifespan reference charts for HV reactivity and reveal a dissociation between oscillatory and aperiodic parameters: aperiodic offset captures shared metabolic vulnerability that transcends diagnostic boundaries and emerges as a candidate transdiagnostic biomarker.