REGION-SPECIFIC EFFECTS OF THE ANTIEPILEPTIC DRUG AND ENVIRONMENTAL POLLUTANT CARBAMAZEPINE ON HUMAN BRAIN DEVELOPMENT

Prenatal exposure to antiepileptic drugs (AEDs) is associated with an increased risk of neurodevelopmental disorders, including cortical malformations, cognitive deficits, and autism. Many widely used AEDs are chemically stable and poorly removed by wastewater treatment, resulting in chronic, low-level environmental exposure. This has raised concern that persistent AED pollutants may contribute to the global rise in autism prevalence. However, studying long-term, low-dose exposure is challenging, particularly in humans, as it overlaps prolonged and complex stages of brain development.
Here, we established a scalable human brain organoid platform to interrogate AED-induced developmental toxicity using a two-step paradigm that begins with high-concentration exposure designed to maximally perturb development and identify sensitive pathways, followed by systematic down-titration to environmentally relevant doses. Human cortical organoids (hCOs) derived from two iPSC lines were chronically exposed to therapeutic concentrations of carbamazepine (CBZ), a low-affinity voltage-dependent Na⁺ channel blocker that is commonly prescribed as an AED.
Across 120 days of hCO development, CBZ induced a biphasic phenotype characterized by accelerated early growth followed by significant late-stage size reduction. These changes were associated with putative disruptions in cortical progenitor cell-cycle dynamics, neurotoxicity, and aberrant gene expression. Fast AAV-mediated GCaMP imaging revealed unexpected neuronal hyperactivity, suggesting a stress-excitotoxic cascade preceding structural decline. Notably, exposure to CBZ in caudalized brain organoids did not produce comparable effects, indicating regional specificity. Ongoing analyses aim to predict vulnerability at environmentally relevant exposure levels. Together, this framework provides a human brain–region system to evaluate chronic AED pollutants and their potential neurodevelopmental risk.