Chronic trauma can affect this system by making it hyperactive or hypoactive. When the system becomes hyperactive, it fails to shut off when it is no longer needed, resulting in high levels of cortisol circulating in the body (Holochwost, 2021). Although the effects of cortisol are beneficial for responding to threats in the environment in the short term, over the long term cortisol can cause physical damage that contributes to psychiatric disorders. Trauma exposure can lead to prolonged cortisol exposure, and a dysregulated HPA axis may be unable to adequately regulate cortisol exposure in response to stress. When left unchecked, high circulating levels of cortisol can saturate the brain and induce brain damage that impedes future functioning (Holochwost, 2021). For example, in instances of prenatal
trauma, prolonged exposure to stress hormones during fetal development may contribute to a dysregulated HPA axis when the child is born. If the environment further contributes to HPA axis dysregulation, the child may develop into an adult with an HPA axis system that reacts more strongly to stress than would be seen in adults with a well-regulated HPA axis. Conversely, repeated trauma can also cause the system to fail to respond when needed, blunting the response to actual future threats (Holochwost, 2021). In either instance, clinicians should be aware of physiological dysregulation in clients and recognize hyper- or hyposensitivity to stress as a symptom of trauma. occurs out of cognitive awareness is allostasis . Mediated by the nervous, endocrine, and immune systems, allostasis is highly beneficial when it is rapidly mobilized and terminated when it is not needed (McEwen, 2020). When “prolonged, the regulatory wear-and-tear on the body—the allostatic load—can undermine health. Trauma is one of the primary culprits of allostatic load; therefore, holistically treating trauma includes addressing the indirect health consequences of allostatic load (e.g., metabolic diseases or cardiovascular diseases). the voice box and facial muscles to express danger to others. If the fight–flight system is engaged, the vagus nerve tells the heart to speed up and the lungs to generate more oxygen. If all else fails, the vagus nerve may send the message to the deeper viscera (e.g., kidneys, stomach, intestines) to shut everything down for a freeze response (i.e., heart rate drops and the gut literally empties; van der Kolk, 2014). Repeated and sustained traumas can impair polyvagal function in clients. Some people may have relied so heavily on the freeze response during their chronic trauma exposures that they jump right to the freeze response in reaction to any arousing stimulus (e.g., a loud noise). Clinicians can go beyond talk therapy when treating trauma and help clients recalibrate their polyvagal function with mind–body work and breathing techniques. world. There are conflicting theories as to the specificity of brain regions associated with memory in general and trauma memories in particular. However, there is strong evidence to suggest that trauma memories, particularly for those who experience PTSD, are more strongly associated with implicit memory systems (Thome et al., 2019). This holds important implications for treatment, in that there may be limitations to simply talking about a traumatic memory, as it may only address explicit memory that can be accessed through language. Additional benefits may be found through efforts to engage aspects that are stored as implicit memory and contain elements of sensations, emotion, images, feelings, and dream states (van der Kolk, 2014). very active and sets off the alarm system by stimulating the hypothalamus into communicating with all the parts of the body that need to respond to the threat, including the adrenal glands, which produce large amounts of the stress hormones cortisol and adrenaline (as explained in the earlier section on HPA-axis dysregulation). In this way, the activity of the amygdala initiates the autonomic nervous system’s response that readies a person to respond with fight, flight, or freeze. It is important to understand, with regard to PTSD, that although the amygdala sets the trauma response into motion, the activity of the hippocampus is often suppressed during trauma and the usual abilities to process and store an event are not available.
Allostatic Load and the Consequences of Stress Dysregulation Chronic trauma can overwork an individual’s physiology to a point at which it contributes to long-term health consequences, including obesity, cardiovascular disease, diabetes, fibromyalgia, and chronic fatigue (Gordon, 2021). The bodily “wear and tear” of chronic trauma is called allostatic load (McEwen, 2020). When the human body detects changes in the environment (e.g., a temperature change), it relies on physiological adaptations that help regulate balanced functioning (e.g., shivering in response to temperature drops). This homeostatic adaptation that often
Polyvagal Theory Polyvagal theory (Porges, 2018) is another important concept that brings to light the underlying biology of trauma, illuminating problems that might not be immediately apparent but that can be treated in a therapist’s office. The term polyvagal refers to the branches of the vagus nerve, which helps connect various organs in the body for communicative purposes, including connecting the brain to the heart, lungs, throat, stomach, and intestines. This interconnection facilitates the full-body response to trauma. A person who experiences danger or stress responds in any or all of three ways: They call out for help and express their distress to others (social engagement); they fight back or decide to take flight (fight–flight); and they shut down (freeze; van der Kolk, 2014). The vagus nerve helps engage all of the various bodily systems in each of these three reactions. When an individual evokes social engagement, the vagus nerve enlists the help of Explicit and Implicit Memory Explicit memory (i.e., conscious memory), involves recollections of personal events related to time and space as well as our general knowledge and is largely a function of the prefrontal cortex (Thome et al., 2019). This area is where the general fund of everyday memory is stored and processed, usually in the form of language, words, and visual states and is related to the development of a sense of self (Thome et al., 2019). Implicit memory (i.e., unconscious memory) is found primarily in the limbic system. Another name for this type of memory is somatosensory (from the Latin soma, meaning physical, and sensory, of the sense organs) memory, and it involves the part of the brain that does not require conscious processing during encoding or retrieval. Such memories include behaviors, emotions, and images and form our reactions to our external Memory Storage during Stress Continual cortisol exposure associated with traumatic exposure and reminders can lead to abnormal cell growth in the amygdala and damage to the hippocampus and prefrontal cortex (Lupien et al., 2018). As the processing abilities of the hippocampus and the prefrontal cortex become inhibited, they may block encoding of explicit memory. They are rendered inactive, and the individual’s response is automatic, driven by the alarm bells of the amygdala. This is useful when a person inadvertently steps in front of a speeding train; however, it has serious implications when the person has endured chronic trauma and the alarm bells continue to ring, even when there is no longer an objective need for them. When a person is traumatized, the amygdala, which governs the emotional responses, becomes
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