Stress and Effects on Brain

Stress and Effects on Brain

Stress and Its Effect on the Brain

Neuropsychological research into human stress response is extensive, although progress in understanding the chemical changes in the brain due to stress has only happened in the last 30 years (Wallenstein, 2003). Stress is an important field of scientific research since it spans from distress in everyday life to more extreme manifestations of stress in mental disorders such as depression (Modell & Holsboer, 2005) and schizophrenia (Lewine, 2005). Stress touches most every child and adult's life in various ways. Traumatic stress rises in the events of war, abuse, assault, rape, childhood loss, or car accidents, among other events. Often such events lead to posttraumatic stress disorder (PTSD), which is a pervasive form of chronic illness (Mueser, Rosenberg & Rosenberg 2009). Other factors such as poverty, illness, work pressure, and difficult life conditions also create stressors for the human brain and body (McEwan, 2002). These are sometimes felt as chronic and persistent. This paper will use contemporary sources of research and scientific models to discuss the neuropsychological basis for stress and the effects of the brain's stress response on a person's thoughts and emotions. While its focus will be on chronic stress, PTSD is considered as well since it is an important original source for the development of chronic stress.

The widespread use of the term stress in psychology gained currency with Selye (1956). Selye formulated a biologically-based understanding of stress. He focused on the body's general adaptation to a challenging stimulus through a syndrome of bodily changes. This was the start of psychological thinking about stressors that both directly harm the person physically and put the body out of harmony because of any perceived psychological fear of harm. Later research shifted the emphasis away from pure biological reflex toward how environmental stimuli are perceived cognitively and reacted to emotionally (Bremner, 2002). In other words, stressfulness came to be viewed not just as the brain's static chemical or metabolic response to an event, but as a dynamic and alterable part of the interaction between a person's mental functioning, past social experience, and the environmental conditions of the challenging stimulus itself (Bremner, 2002). This led to the contemporary research models that investigate not just the effects of stress but the environments that cause stress.

The physical effects of stress on the brain are evident. The brain's stress response originates in the hypothalamus, which is located at the top part of the brain stem and is responsible for a number of regulatory functions like body temperature and the dispersal of hormones into the blood stream (Wallenstein, 2003). The hypothalamus has a dynamic relationship with the pituitary gland that controls the human endocrine system and the adrenal glands which secrete adrenaline (Wallenstein, 2003). Both of these are extremely important in maintaining the body's hormonal balance and preventing bodily deterioration or disease (Wallenstein, 2003). They are vital to the body's fight-or-flight mechanism of self-preservation. Stress reactions arise from the hypothalamus as natural physiological responses to stressful physical, psychological, or social situations (Wallenstein, 2003). The physical stressors such as those that enact a fight-or-flight mechanism are temporary and involve sudden increases in glucose and adrenalin for energy (Wallenstein, 2003).

It has been determined, however, that more long lasting physical effects occur with psychological stress as a result of prolonged or excessive exposure to stress hormones. The release of hormones like cortisol, norepinephrine, and adrenaline, if excessive due to excessive lengths of stressful situations, can have negative consequences on bodily organs (Bremner, 2002). Chronic stress can increase the stomach's proneness to ulcers, increase risk of heart disease, diabetes and asthma, impair the immune system, and accelerate artherosclerosis, among other harmful physical effects that have been studied and documented (Bremner, 2002, pp. 6-9). Research continues to show that stress has effects correlated with a decline in physical health and with a heightened susceptibility to negative symptoms.

Chronic or traumatic psychological stress can also cause physiological changes in the body as an adaptation mechanism. For example, researchers at Emory University discovered that childhood abuse created lasting alterations in physiological response to subsequent stress (Heim et al., 2000). This means that in traumatized people, stress reactions are heightened or exaggerated afterwards. Over time, these changes can create an exaggerated response to other stressors, can decrease the functioning of the immune system, and may lead to a higher proneness toward mood and anxiety disorders (Wallenstein, 2003, p. 55). In other words, stress can create a life-long physiological change in and impairment of brain and body functioning. Such recent findings suggest that victims of stress may in fact suffer from a neurological disorder rather than just from a character flaw, mental weakness, or bad luck.

Chronic stress can impact individual perception and thinking in significant ways. Research in cognitive neuropsychology has been particularly helpful in identifying some of these patterns. Psychiatrists at the Dartmouth Medical School have identified certain common styles of thinking present in those who as a result of traumatic stress suffer from chronic life stress (Mueser, Rosenberg, & Rosenberg, 2009, pp. 99-120). These thought patterns, or schemas, shape the individual's perception of the world and have a degree of negative control over their emotions (Mueser, Rosenberg, & Rosenberg, 2009). The problem is that they are inaccurate and destructive thoughts and beliefs. They exacerbate distress rather than alleviate it. For example, such stress-influenced minds have a tendency to catastrophize (worst case scenario), overgeneralize the negative by jumping to conclusions, and think in terms of extremes and absolutes ("the world is all bad" or "I'm a failure since I'm not perfect") (Mueser, Rosenberg & Rosenberg, 2009). They also overestimate the risk of bad things happening, attribute truth to their feelings ("I feel sad, so my life must be hopeless"), inaccurately blame themselves when they are not responsible for something, and ignore the positive by focusing strictly on the negative (Mueser, Rosenberg & Rosenberg, 2009). The person suffering from this kind of stress, therefore, is in the grip of false perceptions and their resulting negative emotions. Their ability to manage life experience in an unstressful way is impaired unless they are able to find ways to change their beliefs and interpretations of the world and of themselves.

Stress has been linked to more serious impairments such as PTSD, depression, somatic disorders, anxiety disorders, and substance abuse. Bremner (2002) argued that these disorders may be considered in relationship to a "common stress-induced neurological deficit" (p. 34). That is to say, stress actually changes the way the brain operates. In even more extreme cases, studies have shown clear connections between stress and the mental disorder of schizophrenia (Lewine, 2005). While most researchers understand that there are genetic predispositions in those who develop schizophrenia, they generally realize that environmental factors combine with this inherited vulnerability to produce the disorder (Lewine, 2005). In other words, stress contributes to the formation and perpetuation of schizophrenia. It effects the person's cognitive appraisal of the environment, which when fused with biological predispositions give rise to serious mental distress and distortions.