New Research Shows Childhood Maltreatment Linked to Adult Health Problems

Children who are abused or neglected suffer the harmful physical and psychological health effects into adult life, long after the maltreatment ends, researchers at the Dunedin Multidisciplinary Health and Development Research Unit have shown.

The study, based at the University of Otago, has followed a group of 1,000 children, born in 1972/73 in Dunedin, throughout their lives. Study members were most recently assessed at the age of 32, in 2004/05. Researchers compared adult inflammation levels to childhood maltreatment experienced by study members while they were growing up.

The researchers found that children suffering psychological maltreatment were twice as likely to show high adult inflammation levels as children who were not maltreated.

Inflammation, or swelling, is the body’s natural response to stress. It helps to prevent the spread of infection and promote tissue repair after an injury. Inflammation is also a response to psychological stress, such as feeling threatened or frightened. However, the inflammatory response needs to be switched off quickly, especially if there is no actual physical harm. Otherwise, the inflammation itself has harmful effects, and what starts out as a natural defense ends up being a health risk. Increased inflammation in adults is predictor for adult diseases, such as heart disease and respiratory illnesses.

Associate Professor Richie Poulton said that the research has direct implications for modern medicine and public-health programmes. Since maltreated children have an increased risk for adult inflammation, they also have increased risk for adult disease and illness. Information about maltreatment experiences in early life could help to identify apparently healthy adults who have hidden risk for heart disease early enough to prevent it.

Preventing maltreatment of children could also reduce the prevalence, burden, and high cost of poor adult health. While prevention programmes are currently available, childhood maltreatment is still a dramatically widespread phenomenon worldwide.

The research was published in the American journal Proceedings of the National Academy of Science.

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FACT SHEET
Childhood Maltreatment Predicts Adult Inflammation in a Life-Course Study

THE FINDINGS:
Maltreated children are twice as likely to show clinically-relevant inflammation levels as adults (20 years later) compared to non-maltreated children.

THE STUDY:
This finding comes from the Dunedin Multidisciplinary Health and Development Study, which has followed a group of 1,000 children born in 1972-73 in Dunedin throughout their lives. Study members were most recently assessed at the age of 32, in 2004/05.
Among children in the Study who experienced maltreatment, 33% showed clinically-relevant inflammation levels at age 32. However, among children with no maltreatment history, only 18% showed clinically-relevant inflammation levels. Our findings indicate that maltreated children suffer effects into adult life, long after the maltreatment ends, and that these effects include harm to both physical and psychological health.
Because inflammation levels can be influenced by medications (e.g., statins, estrogens) and disease (e.g., infections, inflammatory disorders), we repeated our analysis excluding Study participants taking anti-inflammatory drugs or showing extreme inflammation values. Even in this restricted sample, childhood maltreatment still predicted adult inflammation.

WHY IS THIS IMPORTANT?:
How does stress get under the skin? Stress is often cited as a major cause of modern disease. It has been reported that early-life stress has long-term effects on health; for example, childhood maltreatment increases the risk of heart disease [1]. However, it is still not clear how stress leads to poor health. Because inflammation predicts the development of heart disease, the increased inflammation levels we observed in adults who were maltreated as children may be one of the explanation for why early-life stress influences adult health.
Hidden wounds of maltreatment? Many apparently healthy individuals can have mildly elevated inflammation levels of which they are unaware. However, even such mild elevations are associated with illness, including heart disease [2]. We found that adult survivors of childhood maltreatment who appeared to be healthy were twice as likely to show clinically-relevant inflammation levels compared to non-maltreated individuals. Information about maltreatment experiences in early life can therefore help to identify those apparently healthy adults who have hidden risk for heart disease early enough to prevent that heart disease.
Health is not a state, but a lifetime achievement. Public-health interventions for medical illnesses are generally targeted at adults, because risk factors for disease (e.g., poor diet, smoking) are more easily observed in adults. However, this study shows that early-life experiences can have long-term influences on health. As maltreated children are at increased risk for adult inflammation, they are also at risk for adult medical illnesses. Preventing maltreatment could therefore reduce the toll of medical conditions in adulthood. While prevention programs are available and implementable [3], childhood maltreatment is still a dramatically widespread phenomenon worldwide [4].

BACKGROUND INFORMATION:
How we measured childhood maltreatment. Evidence of childhood maltreatment during the first decade of life included rejection by the child’s mother, frequent changes of primary care-giver, physical abuse resulting in injury, and sexual abuse. 10% of the children had more than one of these forms of maltreatment.
How we measured inflammation. Although the effects of the inflammatory response are often evident at the site of an infection or a wound, inflammation is a process involving the whole body. It is measured through blood tests. We drew blood from Study members at age 32 years and measured the levels of different clinically-relevant inflammatory markers, such as C-reactive protein, fibrinogen and white blood cells count. Childhood maltreatment predicted adult inflammation whatever the inflammatory marker we tested, strengthening the robustness of our findings.
How maltreatment could lead to inflammation. Inflammation is most commonly known as a response to physical trauma. When you are injured, inflammation helps to prevent the spread of infection and promotes tissue repair. What is less commonly known is that inflammation can also occur in response to psychological trauma [5]. After all, stress is the response to impending danger. When we experience losses and threats in our lives, we are, in a sense, physically frightened. That fright, or stress, may lead to inflammation. However, if physical harm does not occur, the inflammatory response needs to be switched off quickly. If it is not, the inflammation may itself have harmful effects. As such, what starts out being a defense (the inflammatory response) can end up being a health risk.
Limitations of the Study. We tested whether the link between childhood maltreatment and adult inflammation was due to the fact that maltreated children grew up in poor families, or to the fact that they had less healthy lifestyle (e.g., had poorer diets, smoked more). It was not.
This suggests that there is something about childhood maltreatment, presumably the experience of traumatic stress in a critical phase of development, which specifically influences inflammation processes across the lifespan, and the risk for disease. Nevertheless, it is possible that some factors that we failed to measure may account for the long-term association between childhood maltreatment and adult inflammation. The ideal study design for ruling out all possible alternative explanations would involve randomly assigning children to maltreatment in an experiment. Clearly this is not ethical. For this reason, observational studies such as ours are crucial.

Our findings are based on individuals living in New Zealand and require replications in other countries.
We do not know whether these findings will generalize to all ethnic groups.
We studied a group of children born in the early 1970s, and they were not old enough in 2005 to show clinical outcomes, such as heart disease. Instead, we focused on physiological processes, such as inflammation, that are known to predict the risk for heart disease in midlife and old age. We aim to continue to follow this cohort into later life.

PUBLICATION SOURCE:
Proceedings of the National Academy of Science USA

AUTHORS:
Andrea Danese, Carmine Pariante, Avshalom Caspi, Alan Taylor, Richie Poulton
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1 see Dong M. et al., 2004, Circulation, http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dop...
2 see Ridker P. et al., 1997, New England Journal of Medicine, http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dop...
3 see Olds D.L. et al., 1997, JAMA, http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dop...
4 see Paulo Sérgio Pinheiro, 2006, World Report on Violence against Children, United Nations Secretary General, Geneva, Switzerland, http://www.violencestudy.org/r25
5 see Glaser R. & Kiecolt-Glaser J., 2005, Nature Review of Immunology, http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dop...