Specifically, the ACE Study model relies strongly on the idea that adverse childhood experiences create a burden of psychological stress that changes behavior, cognitions, emotions, and physical functions in ways that promote
subsequent health problems and illness.22 Among the hypothesized pathways, adverse childhood experiences lead to
depression and posttraumatic stress disorder, which in turn can lead to substance abuse, sleep disorders, inactivity, immunosuppression, inflammatory responses, and inconsistent health care use,
possibly leading to other medical conditions later in life.23, 24 Therefore, childhood behavioral and emotional symptoms very likely represent a crucial mediator linking adverse childhood experiences and the longer term health - related problems found in the ACE substudies.