3.3: Stress and the Brain
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Stress has many definitions, but according to Richard Lazarus, stress is a state of anxiety produced when events and responsibilities exceed one’s coping abilities. In this way, stress relies not only on environmental factors, but on cognitive appraisals of these factors (Myers, 2004). The cerebral cortex perceives the stressor, the hypothalamus stimulates the pituitary gland to release epinephrine and norepinephrine. This in turn stimulates the adrenal glands to release the hormone cortisol (Myers, 2004). Stress affects many other areas of the body, such as the amygdala, which produces a fear response. It seems to hardwire the brain differently. Middle-aged rats that had undergone early life stress had abnormal brain-cell activity and memory loss (Brunson et. al., 2005).
The sources of stress are numerous: from catastrophes such as Hurricane Katrina, significant life changes, poverty and inequality, to daily hassles like traffic tie-ups and demanding jobs (Myer, 2004). Especially in urban and overcrowded environments, psychologist s see links between everyday stressors and hypertension, and unhealthy behaviors such as lack of sleep and alcoholism (Lazarus & Folkman, 1984). In fact, the leading causes of death today in America are linked to lifestyle and stress. According United Nations Security Council, about half of the world’s children grow up in extremely stressful environments (poverty, violence, war, abuse), which means that these children may have impaired cognitive abilities later on in life.
According to research by Janet Rodin, the less perceived control of a situation, the greater the stress. The elderly that lived in nursing homes, were lonely, and had to be fed, dressed, and changed, felt significantly more stress and had shorter lifespans than their independent, active counterparts. Females seem to be more susceptible to stress and depression. After experiencing traumatic events, females are twice as likely as men to develop Post Traumatic Stress Disorder, where humans develop maladaptive behaviors such as avoidance, reduced responsiveness and guilt (Myers, 2004).
However, mindful exercise, such as Tai Chi, meditation, and aerobic exercise decrease stress response and promote overall well-being (Sandlund and Norlander, 2000). In a University of Wisconsin study, participants who did meditative exercises showed more electrical activity in the left side of the frontal lobe, indicating that they had a lower anxiety and a more positive emotional state (Davidson, 2003). Meditation, yoga, and other relaxation exercises also assist in autonomic reflexes. This is called conscious control. Through these practices, it is possible to gain control over the sphincter muscles in the anus and bladder. Yoga has been shown to help control heart rate, blood pressure, and other autonomic functions. These are learned behaviors - they involve the formation of new pathways in the brain.
Researchers have also found the correlation between a social support network of close friends and family and less physiological stress effects (Brown and Harris, 1978). Stress Inoculation Training and Hardiness Training are cognitive behavioral techniques that work to improve stress resistance through analyzing stressors, teaching coping techniques, and changing behavior so that the patient feels more assertive and in control (Kobasa, 1986). Drugs, such as beta-blockers, which reduce stress arousal, anxiolytic drugs, such as minor tranquilizers, and anti-depressant drugs, which treat severe anxiety, can also be used to combat stress.