trauma and toxic stress, changes the physiology and response mechanisms of the brain and body.

Speaker and Forum member Rowell Huesmann explored this concept in discussing the contagious nature of violence, or how violence can spread from person-to-person or community-to-community. He noted that individuals living in violent environments are socialized toward violence as a “normal” response, changing social structures and interpersonal relationships. Violence also increases aggression and aggressive behavior, which reinforces itself in a positive feedback loop, a concept both Drs. Milante and Hemenway identified at the community and societal levels as well. In particular, Dr. Huesmann referenced a longitudinal study from Columbia County, New York, which has been ongoing since 1960, and shows evidence of increased aggression in later life in children exposed to violence (particularly television violence). Dr. Huesmann also referenced his work in Israel and Palestine on aggressive behavior of youth in both places; the experience of living in a violence environment shows impact on aggression toward peers in each group. Further details can be found in Chapter 6.

Dr. Shonkoff explored some of the evidence of the neurobiological transformation that occurs as a result of violence (see Chapter 6 for more details). He described the natural physiological response to stress as evolutionary adaptation. For example, increased heart rate, shorter breathing pattern, high alert to external stimuli, and other processes are a result of the activation of the sympathetic nervous system to the perception of hazard in the external environment. When a person is exposed to high levels of stress for extended periods of time in childhood, the body learns to adapt and accepts the high level of arousal as typical. Over time, this becomes detrimental because the body wants to maintain these high arousal levels when they are no longer necessary. This biological embedding results in individuals who are more likely to aggress or to see aggression where there is none, to respond to nonstressful situations with violence or anger, and to experience adverse outcomes of chronic stress throughout life. In short, cumulative well-being for such individuals is less (Figure 4-1). As Dr. Shonkoff stated, “What was biologically adaptive becomes socially maladaptive.” Dr. Shonkoff also noted two pathways that may occur simultaneously and can result in adverse health outcomes later in life—the first is that adversity in childhood can have behavioral effects that result in risk taking, and the second is that such adversity also has physiological effects that result in psychological disruption.

Dr. Shonkoff cited two studies showing long-term physiological effects related to child maltreatment. The first, the Adverse Childhood Experiences (ACE) study, is an ongoing study of a large cohort who self-reported abuse and neglect in childhood, which correlates to chronic health outcomes experienced in adulthood (Felitti et al., 1998). The second is a study from

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