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Chapter 14

Chapter 14 Notes.doc

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PSYC 328
Blaine Ditto

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PSYC328 Chapter 14 Notes What Is Psychoneuroimmunology? • Psychoneuroimmunology: interactions among behavioural, neuroendocrine, and immunological processes of adaptation • Immune system is the surveillance system of the body. Its primary function is to distinguish between what is “self” and to rid of what is foreign. • Natural immunity is involved in defense against a variety of pathogens. Granulocytes (neurtrophils and macrophages) are involved in natural immunity. They release toxic substances at the site of injury. Macrophages release cytokines that lead to inflammation and fever and promote wound healing. Natural killer cells recognize non-self material and break them by releasing toxic substances • Specific immunity is slower and more specific. Lymphocytes are involved that have receptor sites on their cell surfaces that fit with only one antigen and thus respond to only one invader. • Humoral immunity is mediated by B lymphocytes which protect against bacteria and prevent viral reinfection. • Cell-mediated immunity involves t lymphocytes from the thymus gland operates at the cellular level. Cytotoxic (Tc) cells destroy virally infected cells. Helper T(h) cells enhance the functioning of Tc cells, B cells, and macrophages by producing lymphokines (counter-regulatory function that suppresses immune activity). • Assessing immunocompetence: indicators of immune functioning: • Measuring number of different kinds of cells in the immune system by looking at blood samples → counting the numbers of T, B, and NK cells and assess the amount of circulating lymphokines or antibody levels in the blood → • Assessing the functioning of immune cells → activation, proliferation, transformation, and cytotoxicity of cells. • Ability of lymphocytes to • Kill invading cells • Reproduce when artificially stimulated by a chemical • And → White blood cells to ingest foreign particles • Mitogenic stimulation technique: more proliferation in response to mitogen the better cells are functioning Another measure: the degree to which an individual produces antibodies to a latent (not active) virus. If our • bodies begin to produce antibodies to these latent viruses, it is a sign that the immune system is not working well enough to control them. Levels of antibodies to these latent viruses are another measure of how well the immune system is • functioning. • Producing antibodies to a vaccine is another measure of immune functioning. • Those with higher stress exposure were more likely to show an inadequate antibody titre (also compromised by substance use). Those who coped through emotional-focused copying were more likely to have an adequate antibody titre • If these indicators suggest that the immune system is working effectively, a state of immunocompetence is said to exist • If these suggest that immune functioning is disrupted a state of immunocompromise is said to exist • Wound healing: They heal faster when the immune system is functioning more vigorously. Psychological distress impairs the inflammatory response that initiates wound repair. This is a critical because if demonstrates a relation to health outcomes (stress impairs wound repair due to surgery and may prolong recovery) • Stress and Immune functioning: stressors can adversely affect the immune system. This research began with animal studies showing that experimentally manipulated stressors altered immunologic functioning and increased susceptibility to disorders under immunologic regulation. • Stress and immunity in humans: human beings likely evolved so that in response to sudden stress, changes in the immune system could take place quickly, leading to wound repair and infection prevention. • Short term stressors produce a fight-or-flight response and elicit immune responses that anticipate risk of injury and possible entry of infectious agents into the blood stream. • Now rarely do short term stressors involve wounds, but the system leads to marked increases in both natural killer cells and large granular lymphocytes. Thus an acutely stressful event causes immune cells to redistribute themselves to fight off infection. • Specific immunity though, decreases in response to acute short-term stressors. Immediate short-term stressors produce a pattern of immune responses involving upregulation of • natural immunity accompanied by downregulation of specific immunity • Brief naturalistic stressors of several days’ duration change cytokine production, indication a shift away from cellular immunity toward humoral immunity. • Chronically stressful events (living with chronic illness, being unemployed, etc..) are tied to all functional measure of the immune system: cellular and humoral downregulation. • Stronger among those with pre-existing vulnerabilities. • Chronic inflammation → wide range of disorders (heart disease and decline in cognitive performance) • The body’s stress systems appear to partially regulate these effects: • Stress engages in sympathetic nervous system → immediate effects of increasing immune activity especially natural • killer cells • HPA axis (hypothalamic adrenocortical functioning) • → immunosuppressive effects • →release of glucorticoids such as cortisol which reduces the number of white blood cells, affects the functioning of lymphocytes and reduces the release of cytokines which limits communication with the immune system • Cortisol can also trigger apoptosis (cell death) of white blood cells • Downward modulation of the immune system by the cerebral cortex via release of neuropeptides • Examples of stress studies: • investigation of the impact of space flight on astronauts’ immune functioning (11 astronauts, flights ranging from 4-16 days studied before and after landing) • Space flight associated with an increase in the number of circulating white blood cells and natural killer cells decreased. • At landing, catecholamines (epinephrine and norepinephrine) and white blood cells increased significantly. Suggests that the stress of space flight and landing produces a sympathetic nervous system response • that mediates redistribution of circulating leukocytes • Closer to home examples: Hurricane Andrew →Changes due to sleep problems • Older adults → lower antibody response to influenza vaccine, but for those with strong social support systems antibody titers were stronger • A study showing that those who blamed themselves after an incident showed elevations in proinflammatory cytokine activity → self-related emotions can also change inflammatory processes • Anticipatory stress associated with a decrease in T(h) cells • Health risks: immune modulation produced by psychological stressors can be sufficient to lead to actual effects on health • Autoimmune disorders: the immune system attacks the body’s own tissues, falsely identifying them as invaders (ex: Graves’ disease, chronic active hepatitis, lupus, multiple sclerosis, …) • women develop in their twenties- they may be vulnerable because of • hormonal changes relating to estrogen testosterone may help protect against autoimmune disorders – short supply in women • • during pregnancy, mother and fetus exchange bodily cells which can remain in the mother's body for years • the likelihood of suffering from one and then contracting another is relatively high • genetic factors are also implicated in autoimmune disorders • negative affect and immune functioning: stress may compromise immune functioning because it increases negative emotions • depression associated with alterations in cellular immunity- lowered proliferative response of lymphocytes to mitogens, lowered NK cell activity and alterations in numbers of white blood cells • relationship between depression and immunity - the more depressed the more compromise of cellular immunity is likely to be found. Also linked with prolonged inflammatory responses • Stress, immune functioning and interpersonal relationships: • study- bereaved group showed less responsiveness to mitogenic challenge • loneliness- poorer health and show more immuncompromise • people with insecure attachments to others show lower NK cell cytotoxicity marital disruption and conflict: poorer functioning on some immune parameters • • also partner violence, short-term marital conflict (adverse effects fall more heavily on women) • Caregiving: caregivers for friends or family members with a long-term illness had higher EBV antibody titres (poor immune control of latent virus reactivation) and lower percentages of T cells and T(h) cells. • Adverse effects on wound repair, NK cell function defects • → caregivers are vulnerable to a range of health-related problems that may persist well after caregiving activities have ceased protective effects of social support: important role in buffering people against adverse immune change in response • to stress. • Individuals with higher levels of social support had greater NK cell activity vs. poor social support with poor antibody response • coping and coping resources as moderators of stress-immune functioning relationship: • optimism and active coping strategies→ enhanced immune functioning • self-efficacy/personal control → less immunocompromise under stress • 1. reduce the experience of stress itself • 2. reduce tendency to develop depression in response to stressful events • 3. expectancy-based central nervous system modulation of immunologic activity • perceived self control under stressful events influences immune parameters • prioritizing goals and emphasizing relationships, personal growth, and meaning in life may have beneficial biological effects on immune functioning • interventions to enhance immunocompetence: • beneficial effects of disclosure on immunocompetence • relaxation may mute the effects of stress on the immune system • What is Aids: Acquired immune deficiency syndrome • Unknown when, but may have begun in Central Africa in the early 70s. High rate of extramarital sex, little condom use and a high rate of gonorrhea facilitated the spread of AIDS • • medical clinics maybe have promoted in attempting to vaccinate as many people as possible against the common diseases, using needles over and over again • 33 million living with HIV/AIDS worldwide, with a disproportionate number of these individuals being women, children and youth. • Over 60,000 canadians are diagnosed as HIV positive since 1982. • AIDS epidemic is still in its early stages and is now being transmitted to every part of the world. It is the 6 th leading cause of death worldwide (estimated 120 million deaths by year 2030). • AIDS in Canada: (first in 1982) • viral agent is Human immunodeficiency virus (HIV), which attacks the helper T cells and macrophages of the immune system. It is transmitted exclusively by the exchange of cell-containing bodily fluids (semen, blood). • How is HIV transmitted? • Drug users – needle sharing • homosexual men – anal-receptive sex • heterosexual population – vaginal intercourse is associated with the transmission of AIDS, with women more at risk than men. The number of developing AIDS increases with the number of sexual partners (and anonymous sexual partners) • How HIV infection progresses: after transmission, the virus grow very rapdily within the first few weeks of infection and spreads throughout the entire body. • Early symptoms are mild – swollen glands and flulike symptoms. • Later- gradually and eventually severely compromising the immune system by killing the helper T cells and producing a vulnerability to opportunistic infections that leads to the diagnosis of AIDS • HIV infected- abnormalities in neuroendocrine and cardiovascular responses to stress (chronic diarrhea, wasting skeletal pain and blindness). • AIDS eventually leads to neurological involvement. • CNS impairment (variable: develops early or late in some)– forgetfulness, inability to concentrate, psychomotor retardation, decreased alertness, apathy, withdrawal, diminished interest in work, loss of sexual desire. Advanced stages – confusion, dementia, coma • • Antiretroviral therapy: highly active antiretroviral therapy (HAART) is a combination of antiretroviral medications that has dramatically improved the health of HIV individuals. • But since adherence to drug is variable, it poses a major problem for stemming the progress of the virus • A study conducted to test the intervention program (HAART) in conjunction with psychological readiness (health belief model, theory of planned behaviour, and the transtheoretical model) – self-efficacy and motivation were also enhanced. Their readiness for change and coping strategies were explored to maximize adherence success. ← this trial group scored significantly higher on medication readiness compared to the non-treatment group. Intervention also lowered depression • socioeconomic factors may also affect adherence to treatment (ex: housing status that was affordable and stable was associated with better antiretroviral treatment adherence, use of health and social services, health status, and fewer HIV risk behaviours). • Who gets AIDS? • Early on in the Canadian AIDS: Homosexual men and intravenous drug users • aboriginal peoples and other minority populations are increasingly at risk. • Adolescents and young adults are the most at risk because they are the most sexually active group • individuals who have multiple risk factors are at increased risk for AIDS (for example homosexual and a drug user) – study found that it is due to a synergistic combination of different AIDS risk behaviours. • Study: Injection drug users(IDU) more likely to test HIV positive -Aboriginal, economically disadvantaged, more casual sexual partners, unprotected anal intercourse, engage in sex trade, engaging in sex for money or drugs • numbers growing faster among minority women (heterosexual contact and drug use) • pr
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