The Effects of Optimism on Immune Functioning (Literature Review Paper)
This is my literature review (APA) paper for my Health Psychology class. [I slightly modified the format for HubPages). I found the topic very interesting so I would like to share it with HubPages. I hope you find it as interesting as I did.
The Effects of Optimism on Immune Functioning
The Effects of Optimism on Immune Functioning
Optimism: “an inclination to put the most favorable construction upon actions and events or to anticipate the best possible outcome” (Optimism). It has been shown in various studies that optimism can affect the immune system – the body’s defense system. The immune system protects the body from infections (e.g. bacterial and viral) and is influenced by many factors, one factor being positivity or optimism (Linnemeyer, 2008). According to Straub (2007), positive mental states, including unrealistic positive illusions, is linked to healthier physiological functioning. Individuals with positive views about their medical conditions tend to perceive a sense of control. These individuals also have an ability to promote health and longevity, to feel good about themselves, to develop and sustain relationships and to survive in changing and even threatening environments. These features are defined by Straub (2007) as “self-enhancing” cognitions, which can lead to lower physiological and neuroendocrine responses to stress.
Straub (2007) reviewed a study by Shelley Taylor and colleagues (2003). In that study, 92 college students were asked to complete a How I see Myself Questionnaire and a personality scale questionnaire. The personality scales analyzed optimism, extraversion and happiness. One week later, the participants provided saliva samples and performed mental arithmetic (MA) tasks meant to provoke stress. During the MA tasks, heart rates and blood pressure were monitored. The participants who showed self-enhancing features had lower baseline cortisol levels at the start of the MA test, indicating less stress. Once the MA test was underway, the self-enhancers showed lower heart rate and blood pressure responses, compared to the individuals who scored lower on the self-enhancing scale (Straub, 2007). This study implicated that self-enhancers may experience less physiological stress-related deterioration. The study also showed that there is a relationship between self-enhancement features (e.g. optimism, high self-esteem) and neuroendocrine responses (Straub, 2007).
Straub (2007) also showed the effects of social engagement and support on the body’s immune and neuroendocrine responses. Past studies have shown that social support can lead to an increase in lymphocyte count, natural killer cells and cell-mediated immunity. As a result, people with great social support are more likely to live longer and healthier. Straub (2007) also discussed wakeful relaxation (e.g. meditation and breathing exercises). This type of relaxation promotes a decrease in leukocyte counts and an increase in natural killer cell activity. It also improves the functioning of the immune system during stressful events.
One important psychological aspect that can improve neuroendocrine and immune functioning is perceived control (Straub, 2007). Individuals who believe that they have more control over their life’s circumstances are more likely to behave in a way that promotes health. On the other hand, those who feel helpless and lacking control are at risk for illnesses as they do not take action to promote health. In fact, these individuals often engage in health-compromising behaviors because, for example, they believe that if they have cancer, they may as well drink as much alcohol as possible because they will probably die from the cancer anyway. These individuals who lack a sense of control have higher cortisol levels and weaker immune systems (Straub, 2007).
Emotional and Immune Parameters
Optimists are happier individuals because they generally think more positively than their pessimistic counterparts. Happiness is marked by joy and satisfaction, cheerfulness and willingness (Barak, 2006). All mammals have brains that are capable of experiencing happiness and pleasure but happiness can be explained through life events. Biological and personality differences must be considered when studying happiness and optimism. Each individual has a different nervous system, which yields different preferences that lead to different circumstances and thus, different outlooks on life (Barak, 2006). Because everyone has a different outlook on life, each person has different emotional responses. According to Barak (2006), emotional responses are components of physiological interactions. For example, emotional responses can affect the body’s ability to resist disease. Therefore, a positive mood can be beneficial to physiology.
Emotional states can influence the progression of disease and determine the level of resistance or vulnerability to disease (Barak, 2006). An emotional state such as stress causes increases in blood pressure, heart rate and sympathetic arousal. These changes, if chronic, can contribute to the development of heart disease and other related illnesses. Barak (2006) reviewed a study by Watanuki and Kim, who studied the physiological responses of the central and autonomic nervous systems and immune and endocrine systems when pleasant stimuli were presented to subjects. The results of the research showed an increase in secretary immunoglobulin-A (IgA) and a decrease in salivary cortisol. The lower the IgA, the higher the frequency of infection (Barak, 2006).
According to Segerstrom, Castaneda & Spencer (2003), optimism is related to higher immune parameters (i.e. T cells, natural killer cell cytoxicity and cellular immunity), better mental and physical health and greater decrease in natural killer cell cytoxicity. With regard to better mental health, optimism lowers the risk of depression and anxiety. It also positively affects cognitive and behavioral coping pathways (Segerstrom et al., 2003). According to the negative relationship model of optimism, as described by Segerstrom and colleagues (2003), optimism can lead to disappointment and distress when the effort of the optimist is unsuccessful. This model implies that the positivity displayed by optimists is only beneficial when things work out in the end.
The Engagement Model
The engagement model supports the negative relationship model of optimism (Barak, 2006). This model shows that optimists experience higher short-term stress because they are more likely to remain engaged with both conflicting goals. On the other hand, pessimists are more likely to give up on the goals, therefore avoiding further exposure to the stressors. In that model, optimists are hypothesized to fare worse than pessimists on an immunological level when facing goal conflict (Barak, 2006). In a study of community-dwelling women by Segerstrom (2005), optimism had different relationships to T cell percentages and natural killer cell cytoxicity (NKCC). When stressors lasted less than one week, pessimists showed a decrease in T cell percentages while optimists were unaffected. However, when the stressors lasted more than one week, the optimistic women showed lower T cell percentages and NKCC levels. Yet, the pessimistic women showed an increase in T cell percentages and their NKCC levels were unaffected (Segerstrom, 2005).
The engagement model also indicates that when circumstances are easy or straight forward, optimists show a well-functioning immune system. This is due to the principle that engagement leads to solving the problem, therefore getting rid of the stressor (Segerstrom, 2005). Yet, when the circumstances are difficult, there is ongoing engagement and prolonged exposure to stressors in the optimist (Segerstrom, 2005). Similar to the engagement model, the persistence model states that optimists may pay a short term cost of engagement but coping persistence is beneficial in the long run (Segerstrom et al., 2003). As a result, optimistic individuals may enjoy better outcomes and better adaption and coping in the long run. According to Segerstrom (2005), optimism predicts lower ambulatory blood pressure and lower mortality in some cancer patients. However, some studies show that optimists may actually be more vulnerable to dire circumstances than pessimists. This pessimistic view of optimism implies that optimists set themselves up for distress, which has a negative impact on the immune system (Segerstrom, 2005).
Optimistic Cancer Patients
The disappointment hypothesis also relates to the engagement model. This hypothesis makes the assumption that when optimists are “let down” they experience harsher levels of distress which compromises the immune system (Segerstrom, 2005). The model assumes that difficult situations are less distressing for pessimists because they lack the positive expectations that optimists have. However, this hypothesis cannot be indefinitely proven because optimists are not generally “let down.” In fact, optimists are less likely to face disappointment because of their positive mentality (Segerstrom, 2005).
In various observations and studies in the past, optimism has shown a profound positive effect on cancer patients (Carver et al., 2005). A well-studied group of cancer patients is women diagnosed with breast cancer. In past studies of these women, coping reactions, optimism, social support, sexual self-schemas and medical factors have been examined. It has never been entirely understood why some cancer patients cope so much better than other cancer patients in the long run. However, after several studies, it was determined that psychosocial factors play a significant role in patients’ short-term and long-term survival (Carver et al., 2005). In earlier studies, optimism was measured by patients’ confidence about remaining cancer free. Patients answered questions based on the Life Orientation Test—Revised (LOT-R), a standardized test. In each study, emotional distress was measured as well as depression symptoms, social disruption and the patients’ self-rated quality of life (Carver et al., 2005).
In the results reviewed by Carver et al (2005), cancer patients who were in a partnered relationship reported less depression, social disruption and emotional distress and had higher ratings on the quality of life assessment. These patients were also the ones with the highest levels of optimism, based on the various assessment scores. This presumes that having better social resources predicts better psychological well being over time, which leads to greater optimism and less stress or emotional distress (Carver et al., 2005).
Overall, optimism has beneficial effects on the immune system. Optimists are generally happier because they think positively. Positive thinking has been linked to many psychological and physiological benefits. Emotional states have been proven to influence the way illnesses progress (Barak, 2006). Emotional states such as stress are detrimental to the body but optimism in the long run leads to lowered blood pressure, heart rate and sympathetic arousal. This decreases the risk of developing heart disease and other related illnesses. Optimism is linked to higher immune parameters and better mental and physical well being. Optimism also lowers the risk of depression and anxiety. Despite the negative findings in optimism, in the long run, optimism has almost always proven more beneficial than detrimental. Therefore, generally speaking, optimism has shown to have a positive effect on immune functioning.
Barak, Y. (2006). The immune system and happiness. Autoimmune Reviews, 5, 523 – 527.
Carver, C.S., Smith, R.G., Antoni, M.H., Petronis, V.M., Weiss, S., & Derhagopian, R.P. (2005). Optimistic personality and psychosocial well-being during treatment predict psychosocial well-being among long-term survivors of breast cancer. Health Psychology, 24(5), 508 – 516.
Linnemeyer, P.A. (2008, October). The immune system – an overview. Retrieved from http://www.thebody.com/content/art1788.html
Optimism. (n.d.). In Merriam-Webster Dictionary online. Retrieved from http://www.merriam-webster.com/dictionary/optimism
Segerstrom, S.C. (2005). Optimism and immunity: do positive thoughts always lead to positive effects? Brain Behavioral Immunity, 19(3), 195-200.
Segerstrom, S.C., Castaneda, J.O., & Spencer, T.E. (2003). Optimism effects of cellular immunity: testing the affective and persistence models. Personality and Individual Differences, 35, 1615 – 1624.
Straub, R.O. (2007). Health psychology: a biopsychosocial approach (2nd ed.). New York, NY: Worth Publishers.
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