The original ACE (Adverse Childhood Experiences) study, published in 1998, confirmed what physicians, psychologists, social workers, substance abuse counselors and school principals had long suspected: that abuse, neglect and trauma in early childhood have a lifelong impact on health and behavior. But the study surprised even its authors, Drs. Robert Anda and Vincent Felitti, in showing how many people—even among a mostly white, well-educated, medically insured cohort of California adults—were touched by adverse experiences.