A New Normal: An Age-Period-Cohort Analysis of the Transformed Childhood Adversity Landscape in the United States.

Adverse Childhood Experiences (ACEs) are strongly associated with poor physical, mental, and social outcomes, yet few studies have examined ACE prevalence across birth cohorts. We pooled Behavioral Risk Factor Surveillance System (BRFSS) data from 2009-2012 and 2019-2024 (1925-2003 birth cohorts) and analyzed them using an Age-Period-Cohort (APC) model. Early cohorts (circa 1930) reported a mean ACE score < 1 (prevalence of ACE score ≥ 4: ~1 in 20), whereas late 1990s/early 2000s cohorts reported a mean score > 2 (prevalence of ACE score ≥ 4: ~1 in 4). In APC models, the 1955-1979 cohorts had ~50% higher mean ACE scores (incidence rate ratio [IRR]: ~1.50) than pre-1930 cohorts. Additionally, ACE reporting was ~25% lower in 2009 than in 2019 (IRR = 0.75), indicating a strong period effect toward greater disclosure. At the population level, childhood adversity has shifted to a high-prevalence reality, likely reflecting both historical increases across cohorts and a shift toward greater disclosure over time. Addressing this cumulative burden requires integrated, intersectoral policy and safety-net reforms across the health, education, social services, and justice sectors.