The Brain Equity Gap

This book confronts a fundamental crisis in neuroscience research: the assumption that findings from demographically homogeneous populations represent universal truths about the human brain. Rather than treating demographic exclusion as a mere “generalizability limitation,” it reframes it as a scientific validity threat—showing that homogeneous samples can produce systematically biased findings that may be invalid even for the populations studied. The book introduces two interconnected frameworks—population diversity (demographic representation in research) and brain diversity (neurobiological variation across populations). Drawing on PET neuroimaging evidence, it demonstrates that identical symptom severity scores may correspond to markedly different brain metabolic patterns across conditions and populations. Moving beyond theoretical debate, it shows why standardized protocols often fail in diverse populations. Organized into four interconnected parts, the book examines: (1) population and brain diversity in global research, (2) how biased research produces biased AI systems, (3) the erosion of trust across cultures, and (4) practical solutions emerging from six continents. Unlike works that apply Western frameworks globally, it foregrounds authentic international perspectives and explores how exclusion manifests differently across healthcare systems, regulatory settings, and cultural contexts. Written for neuroscience researchers, clinicians, AI developers, graduate students, policymakers, and ethics review boards, the book addresses readers across all regions, not only Western contexts. Current literature often frames demographic diversity as an ethical obligation or a problem of generalizability. This book argues instead that diversity is a requirement for scientific validity. It traces the full pathway by which methodological exclusion generates biased findings, trains biased AI systems, and ultimately erodes public trust—creating a global crisis that demands region-specific solutions. Combining conceptual frameworks with practical tools, the book offers a roadmap for transforming neuroscience from an exclusionary to an inclusive discipline, grounded in empirical evidence that diverse science is better science.