Kinds of Stress
All stress is not alike. According to researchers at The National Scientific Council on the Developing Child, brain research is demonstrating the many ways in which biological events that occur during fetal and postnatal life predispose the child to an
elevated risk of subsequent problems in physical and mental health (National Scientific Council on the Developing Child, 2007a, 2007b). The impact of stressors depends on the kind of stress a child—and later the adult he or she becomes—is subjected to, and investigators have described four major types of stress—positive, tolerable, toxic, and traumatic—that lead to very different outcomes.
Positive stress promotes growth and development and is necessary to a healthy mind and body. When children experience positive stress, they have short-lived physiological responses, including changes in heart rate, blood pressure, and some neurohormones. In the context of supportive relationships from the adults around them, the normally stressful experiences of childhood help a child develop mastery, self-esteem, confidence, self-discipline, and self-control (National Scientific Council on the Developing Child, 2007a, 2007b).
Tolerable stress events are experiences such as death of a loved one, parental divorce, a natural disaster, or an act of terrorism. Tolerable stress may trigger enough physiological response to disrupt brain architecture, but when relieved by the support of caring relationships the brain has sufficient buffering to provide adequate protection for a child’s vulnerable central nervous system. Depending on the child and the degree to which the child’s family support system was overwhelmed, these experiences could have long-term consequences, particularly posttraumatic stress disorder, but the child is far less likely to experience permanent harm (National Scientific Council on the Developing Child, 2007a, 2007b). Most children and adults will recover and suffer no long-term difficulties.
Toxic stress is associated with prolonged and intense activation of the body’s stress response systems when a developing child lacks the buffering necessary from socially supportive people in his or her environment for the brain to be adequately protected. Recurrent child abuse or neglect, severe maternal depression, parental substance abuse, community violence, and family violence all increase the likelihood that a child will be repeatedly exposed to toxic stress.
Because of technological advances in the last few decades, we know now that the child’s brain architecture—the very way the brain is structured—is determined by the interaction of the brain with the environment. When the child is exposed to frightening environments, his or her brain is persistently bathed in elevated stress hormones. These altered levels of key brain chemicals produce an internal physiological state that disrupts the architecture and chemistry of the developing brain. Although individuals differ in how they respond and adapt, the result can be long-term difficulties in learning and memory as well as health-damaging behaviors of many different kinds. Continuous activation of the stress response system also can produce disruptions of the immune system and metabolic regulatory functions (National Scientific Council on the Developing Child, 2007a, 2007b).
Traumatic stress occurs when a person experiences an event that is overwhelming, usually life-threatening, terrifying or horrifying and they are helpless to adequately protect themselves. In situations of traumatic stress, the individual’s coping skills are overwhelmed and they are insufficiently buffered by resources that exist in their social environment. Much of what we describe in this book is a result of exposure to the third and fourth level of stress—toxic stress and traumatic stress—and the impact of exposure on clients, staff, and entire organizations.
In understanding the impact of stress on body, brain, mind, and social context, it is important to recognize that the interactions between the individual, the social environment and the stressors themselves are interactive and complex. Two concepts are helpful in registering this complexity: allostasis and allostatic load. (1) Allostasis, defined as a dynamic regulatoryprocesswherein homeostatic control and balance is maintained by an active process of adaptation during exposure to physical and behavioral stressors, and (2) Allostatic load, is defined as the consequence of allodynamic regulatory wear-and-tear on the body and brain promoting ill health, involving not only the consequences of stressful experiences themselves, but also the alterations in lifestyle that result from a state of chronic stress (McEwen & Gianaros, 2010). Using these bridging concepts, researchers are becoming able to calculate the various kinds and components of stress and its impact on the individual including the impact of socioeconomic factors and the kinds of exposure to childhood adversity that we describe next.