Vincent Felitti of the Kaiser Permanente Medical Centres, collaborating with the Centres for Disease Control and Prevention, conducted a study involving over 17,000 middle-class adults to explore the effects of childhood adversity on adult health. It is now known as the Ace’s study and it examined the relationship between stressful and traumatic early experiences and their impact on long-term health. The study showed how ten categories of adverse experiences have negative consequences decades later on a large number of health risks, social problems and reduced life expectancy. The Ace categories include growing up in a family with different types of abuse, including incest alcoholism, drug abuse, mental illness, criminal behaviour and domestic violence. The ‘ACE scores’ were calculated by adding the number of categories experienced rather than the number of events within one category. It was found that less than half of participants had an ACE score of zero. One in six had an ACE score of four or more. Two-thirds had an ACE score of one or more, indicating that they are more common than not.
The study then matched the ACE score with health risks like heart disease, diabetes, obesity, depression and suicide. For each category the risk increased with an increase in the ACE score with no exceptions. The more ACE scores a person experienced, the greater the likelihood of health problems developing in adulthood. An increase in ACEs also leads to an increase of risk for engaging in destructive relationships, substance abuse, smoking, alcoholism and drug use. Felitti argues that the study shows that it does not make sense to study one category of adverse experience. They do not occur is isolation but are part of a complex systems failure. The Dunedin health and development study has also shown that people who experience childhood maltreatment were found to have elevated levels of inflammation twenty years later.