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Part I
Theory and constructs
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1 Trauma theory
Sandra L Bloom
Introduction
Across the millennia, the human brain has evolved to function as an integrated whole, with mind and body acting in concert, constantly adapting to a wide range of ecological challenges. The complex physiological mechanisms that have developed to accommodate this enormous flexibility are generically known as the human stress response. In the last several decades, the study of traumatic stress â capturing the most extreme mobilisation of the stress response â has garnered a significant body of knowledge and research.
For many years, the word âhomeostasisâ has been used to describe the exquisite balancing act that keeps human bodies functioning within an optimal range and in a state of equilibrium. This primarily involves the autonomic nervous system as it constantly responds to demands for activation or relaxation. More recently, researchers have been substituting the word âallostasisâ, a term that indicates variability in this balancing responsiveness. The sympathetic nervous system is activated as a stressor indicates the need for greater response, including an increased utilisation of energy. Powerful neurochemicals and neurohormones released by the brain stimulate end organs in turn to release adrenaline, cortisol, beta-endorphin, glucagon and others. When the need to respond to the stressor has passed, the parasympathetic nervous system calms that response down, so the organism can return to restoring energy and growth, and to repair any damage. The variable response to a stressor is influenced by the three levels of the brain: automatic responses to survival threats in the brainstem, emotionally-based responses originating in the limbic system, and more complex and even conscious responses that originate in the cortex.
Inadvertently, a linguistic problem has developed in that the word âtraumaâ is being used to describe reactions and results that emanate from events that may not be routinely understood as traumatic. It is not possible to coherently understand traumatic stress and the complex problems associated with it without also considering the other gradations of the stress response: positive stress, tolerable stress, relentless stress (increased allostatic load), and toxic stress. Positive stress is characterised by moderate, short-lived increases in heart rate, blood pressure, serum glucose and circulating levels of stress hormones, and occurs when the body adapts to any change, such as leaving home and getting into a car to drive to work. Tolerable stress refers to responses that could affect brain architecture, but generally occur for briefer periods that allow time for the brain to recover and thereby reverse potentially harmful effects. An increased allostatic load, or relentless stress, are the terms being used to describe the wear-and-tear on the body and brain resulting from chronic over-activity of the same physiological systems that are normally involved in adaptation to environmental challenge (McEwen, 2012). Toxic stress is the term employed to describe the strong and prolonged activation of the bodyâs stress management systems that becomes particularly problematic when it occurs during critical developmental periods, because of the multiple ways that this activation affects the progressive unfolding of basic brain architecture (Shonkoff et al., 2012b).
This extensive variation in control mechanisms tells us a great deal about the problems that can arise for human beings in our modern world. We are still quite capable of responding as our ancestors did to survival threats. But we respond similarly to anything we perceive as emotionally threatening as well as threats to our status, our individual and group identities, and our ideological frameworks. Therefore, to understand the multiple ways in which stress affects people, there is a need to simultaneously understand basic physiology, human development, emotional processing, and cognitive processing, as well as group behaviour and moral systems, and the way each of these critical components of human existence interact with each other. This complexity requires the need for a more thorough understanding of stress, trauma, and human physiology in health and disease or dysfunction.
Stress, adversity, and trauma affects everyone, and the earlier it starts in life, the longer it lasts, the more frequently it happens, and the more distrust develops, the more challenging and long-lasting the effects will be. It is because of this complexity and the intersection with so many other dimensions of science and the humanities that it has become possible for a unified field theory of human behaviour to begin to emerge. A paradigm shift is finally occurring after several hundred years of advancing knowledge that can integrate and unite the varied schools of thought about trauma and the human condition.
Physical responses
Fightâflight
The physical response to danger referred to above is best known as the âfightâflightâfreezeâ response, the basic mammalian survival response. âThe sympathetic nervous system kicks into action during emergencies, or what you think are emergencies. It helps mediate vigilance, arousal, activation, mobilizationâ (Sapolsky, 1998: p.22). This results in increases in blood pressure, heart rate, breathing, accelerated delivery of nutrients to muscles, blunted pain perception, increased blood clotting, activation of the immune system, and a brain that is on alert. At the same time, long-term digestion, growth, tissue repair, and reproduction are all turned off.
The amygdala, an almond-shaped structure found in both the right and left temporal lobes of the brain, is like a âcentral switchboardâ for danger, so that when threat is perceived, the amygdala is activated and sends signals that trigger the full fightâflight response, all of which occurs at an unconscious level. As a result, the amygdala can be âhijackedâ, so that a response to non-dangerous stimuli can occur before there is a chance to think or evaluate a situation (Goleman, 1995). The right amygdala appears to be more influenced by early childhood experiences than the left.
Joseph LeDoux has described a âlow roadâ and a âhigh roadâ of arousal, demonstrating that the low road from perception of potential danger to immediate arousal of the autonomic nervous system is unconscious and fast, while the high road, involving the appraisal process of the cortex, takes twice as long to be activated (LeDoux, 2002). Anyone who drives is aware of this; braking occurs before any conscious decisions can be made.
Chronic stress can result from living in chronically dangerous situations: war zones, domestic violence, incarceration, refugee status, child abuse. But chronic stress can also occur under conditions that are not actually physically dangerous but that are psychologically threatening, including events that are anticipated to happen. It is the generalisation of the stress response that sets humans apart from other animals; humans can elicit a fightâflightâfreeze response in situations that are not physically threatening.
Chronic hyperarousal
Under conditions of chronic stress, something goes wrong as the body repeatedly attempts to mount the necessary physiological responses. The effectiveness of the response diminishes and the body becomes desensitised to the effects of some neurohormones, and hypersensitive to others. The entire system can become dysregulated in multiple ways. This results in a set of highly dysfunctional and maladaptive brain activities (Perry and Pate, 1994). The person experiences this as a state of chronic hyperarousal â a hallmark characteristic of Posttraumatic Stress Disorder (PTSD). Essentially, the baseline level of arousal for the person has changed, with a loss of control of their own responses to stimuli.
Once severely or repeatedly traumatised, people lose the capacity to modulate their level of arousal, they stay hyper-aroused and guarded, and they are unable to calm themselves down, even when there is no danger. They may feel embarrassed by their response, while at the same time they may also be irritable, angry, and frightened for no apparent reason. They may still be prepared to fight or to flee and they may also become flooded with memories, images, and sensations that are overwhelming. As a result, they are likely to feel that they are âgoing crazy.â These reactions can be triggered by internal or external cues.
Fear-conditioning
Once a fear-evoking stimulus has been experienced, âfear-conditioningâ occurs; a state that is very powerful and difficult for the logical centres of the brain to override (LeDoux, 1992, 1994). Because of the vast associational network of the human brain, fear can pair with virtually any stimulus. This happens very quickly at the time of the frightening event, and beyond conscious control. Later, the person is usually not consciously aware of the connection between the fear-provoking stimulus, since the fear-response has become completely automatic. Each episode of danger connects to every other episode of danger, so that the more danger a person is exposed to, the more sensitised that person becomes. This hypersensitivity is known as âkindlingâ and has been associated with not only PTSD but also with episodes of Mania and Depression (Monroe and Harkness, 2005). With each fight-or-flight experience, the mind forms a new network of connections that is triggered by every subsequent threatening experience or stimulus.
Since most individual cell growth and specialisation in the brain occurs after birth in response to complex and critical neurohormonal cues, chronic hyperarousal in childhood means that children are more likely to develop a panoply of destructive symptoms and behaviours in attempts to diminish this unsupportable state. Failure to provide children with sufficient protection from overwhelming stress appears to cause actual impairment in normal brain development. A growing body of evidence suggests that this exposure has long-term detrimental effects on basic brain architecture as well as cognitive, emotional, and social function, and moral development. Researchers studying childhood posttraumatic stress and adversity believe that childhood stress and trauma may be the common link between many medical and psychiatric conditions related to the immune system, the cardiovascular system, and the neuroendocrine system. These findings have been strongly supported by the landmark Adverse Childhood Experiences study (Anda et al., 2010).
Freeze and dissociation
The freeze component of the stress response is strikingly different. If there is no chance for survival by either fight or by flight, the freeze response may automatically occur. The freeze response activates a very different sequence of autonomic nervous system arousal, slowing the heart rate, preserving blood flow, and even simulating death so that a predator loses interest, since predatory behaviour is triggered by movement (Levine, 1997). The dissociative response, the âtemporary breakdown in continuous, interrelated processes of perception, memory, or identityâ (Brewin, 2011: p.211), has much in common with the freeze component of the stress response, although the difference between what happens to prey animals in the wild who do not get caught, and what happens to humans who dissociate at the time of a trauma is significant. Animals who enter the freeze state and who come out of that state of immobility spontaneously are far more likely to survive than animals who are forced to come out of that state. Apparently, the spontaneous recovery of the animal, often through repetitive almost seizure-like motor discharge, is associated with survival after the immediate source of danger has passed (Scaer, 2001). But humans frequently do not spontaneously come out of the acute dissociative state known as âshockâ, and, instead, fragments of the experience may become locked into that dissociative state, unavailable to full biographical narrative. These become the substrates for flashbacks, nightmares, and behavioural re-enactments.
Similarly, animals exposed to inescapable shock âlearnâ to be helpless so that even when they could escape they do not do so. This phenomenon of uncontrollability has been used as a model for chronic dissociation and the freeze response in humans who cannot control the trauma they are experiencing. A viable hypothesis is that the failure of the person to adequately discharge the state of immobility and the dissociative state accompanying it may lie at the heart of the memory disturbances and arousal symptoms of PTSD (Levine, 1997); it is well established that people who dissociate at the time of a traumatic event are more likely to develop PTSD (Van der Kolk and Van der Hart, 1989).
Tend and befriend
More recently, a different form of the human stress response has been captured in the phrase, âtend and befriendâ. It has been proposed that one of the most striking aspects of the human stress response is the tendency to affiliate, that is, to come together in groups to provide and receive joint protection in threatening times. This form of the stress response would have supported survival by arousing the need, particularly in females, to tend to the young and vulnerable, and could be served by circuitry involving the parasympathetic system with the release of oxytocin that then triggers the release of serotonin and dopamine, all of which supports affiliation (Taylor et al., 2000; Taylor, 2006). Differing gender-based strategies would have served evolutionary needs but may now help to explain gender differences in longer-term physical outcomes (Wang et al., 2007; Verma et al., 2011).
Cognitive responses to danger
Information processing
Human beings have two distinct ways of processing information: one under calm, low-arousal states termed ârational-thinking modeâ, and the other occurring during high stress and high arousal, given the term âthe experiential-thinking modeâ. The experiential-thinking mode is automatic, rapid, occurs outside of conscious awareness, and takes precedence under life-threatening conditions. When danger is perceived, humans are physiologically geared to act, not to ponder and deliberate. In situations of acute danger, it is better that humans respond immediately without taking the time for complicated mental processing, so that responses can be more immediate, to save lives and to protect family. Calm rational thinking takes time and when faced with, for instance, a hungry predator, the deliberate and time-consuming nature of rational thought processes can cost oneâs life (Epstein, 1994).
As a result, under conditions of danger, perceptions are radically altered. As heart rate goes up, cognitive processes change radically (Grossman and Christiansen, 2008). First, there is a narrowing of the perceptual field, so that only information relevant to the immediate threat can be absorbed. Diminished or altered sound, tunnel vision or the loss of peripheral vision may also be experienced. Heightened visual clarity about some details of the event may occur, along with a sense of temporary muscle paralysis. There may also be perceptual distortion of time so that everything seems to be in slow motion, and intrusive or distracting thoughts about loved ones or other personal matters may occur. Similarly, flashbulb memories may be experienced, where the individual has a series of vivid images burned into memory, with the rest of the event somewhat confused, out of order, or even missing. Distance distortions, colour distortions, face recogniti...
