psyc 365: Lec 3

Psychoneuroimmunology (PNI)

The study of the relationship between psychological states and the functioning of the immune system

Immunocompetence

The extent to which one's immune system is functioning properly to ward off disease.

What does Psychoneuroimmunology (PNI) link?

Psychology and health.

What systems does PNI examine the interaction among?

The nervous system, the endocrine system, and the immune system.

What factors does PNI consider in immune function?

Biological, psychological, and social factors.

How does psychology affect health according to PNI?

Our psychology (psycho) affects nervous system functioning (neuro), which in turn affects our immunity to disease (immunology).

What is the role of PNI in health care?

It bridges communication between social scientists and health care practitioners.

Measuring Immune System Function in PNI research

Measuring the psychological state in immune functioning is complex.

• The immune system cells are located in many places throughout the body like the spleen, bone marrow, tonsils and small intestine which makes it hard to measure activity.

• Another reason is there are a variety of forms this cellular activity takes places and operates independently of each other.

What are the variables in PNI research?

Independent variable-Some psychological state, Naturally occurring or experimentally induced

Dependent variable-Usually a measure of immunocompetence, Can measure immunocompetence by counting cells or measuring cells in action

What are 2 ways to Measuring Immunocompetence?

1. Enumerative assay - a lab test to count cells for:

1) Minimum number of cells for adequate immune function

2) Balance among types various cell types, such as different types of T cells. The higher the count the better the immune system functions.

2. Functional tests of immunity looks at cells in action. To assess the immune system at work. can be:

1) In vitro - mitogen stimulates activity ex. blood

2) In vivo - measure antibody (AB) production

what are 2 Vivo Tests of Immunocompetence test ?

1. Herpesvirus: Suppression of the immune system increases the herpesviruses and the more antibodies.

• Higher A B counts for herpesvirus-specific antibodies indicate poorer immune-system function.

2. Introduction of an antigen into the body either by injection or nasal spray.

• Count antigen specific antibodies in response to the injection.

• More A B indicate better immunocompetence.

What is Mitogen?

a relatively harmless substance that stimulates immune cell activity as though the immune cell were acting against an invading cell or antigen.

How is Natural Killer (NK) Cell Activity measured?

By in vitro techniques

What is NK cell cytotoxic activity assay?

a test in which the proliferation and effectiveness of NK cells is measured after they have been exposed to diseased cells.

What is NK cell lysis?

Destroying tumour cells by exposing them to NK cells

What are some Methodological Issues in Measurement?

There are many challenges in PNI research:

• Short-term versus. long-term effects. Effects may be different.

• Many forms of immune-system function Statistical significance versus.

• clinical significance Is statistical significance clinically important?

Define Stress

condition in which the demands of a situation are perceived to be greater than our ability to cope with them

How does stress effect immune functioning?

Lab research shows:

• Acute stressors immediately inhibit an effective immune system response

• Personality affects stress response -Stress has long-term effects on immunity

Linking Childhood Adversity with Poor Adult Health

• Growing evidence that early childhood experiences affect health across the entire lifespan

• Process by which experience has permanent effects on the expression of the genetic coding is biological imbedding

What is the Biological Embedding of Childhood Adversity Model?

It is the process by which experience has permanent effects on the expression of our genetic coding and, subsequently, on a range of biological processes this coding affects.

What perspective does the Biological Embedding of Childhood Adversity Model adopt?

It adopts a biopsychosocial perspective.

How do adverse experiences in early childhood affect DNA?

They impinge upon DNA and alter the immune system by permanently changing cells responsible for the regulation of inflammation.

What predisposition do children who have experienced adversity have?

They become predisposed to behaviors that further increase their risk for ill health.

How does Stress relate to Upper Respiratory Tract Infection (UTRI)?

Common illnesses (e.g., cold, flu, coughs, bronchitis) are affected (worsened or started) by stress and it particular types.

What factors interact to predict one's response to stress ? (UTRI)

• Generalized Anxiety Disorder

• Social support

• Positive life events

What is the stress-intrusion score?

A measure of the impact a stressful event has on a person's life.

What does major life change suggest in relation to immunosuppression?

Major life change suggests immunosuppression.

What is the relationship between immunosuppression and exposure to upper respiratory tract infections (URTI)?

Immunosuppression combined with exposure to URTI increases the likelihood of sickness.

what is the main effects model ?

allow us to isolate a factor to determine its unique contribution to illness, they also oversimplify the realities of health and well-being.

• Stress rarely works in isolation. Instead, it interacts with other factors, such as social support, demographics, and personality.

what are Autoimmune diseases?

The development of antibodies that attack the body's own tissue. Ex. rheumatoid arthritis, insulin-dependent diabetes, multiple sclerosis

How can stress affect autoimmune diseases?

-Stress can increase risk of contracting

- Relaxation and meditation can lower pain in arthritis

What is the relation between stress and cancer?

Major life stress sometimes affects cancer like worsens it but not predispose someone to developing cancer.

how are NK cells and cancer related?

NK cells protect against cancer. There are psychological factors that affect NK cell activity under stress.

*Remember that NK cells are primarily responsible for seeking out and destroying abnormal cells. This function makes NK cells crucial in the body's ability to remain cancer free.

While compromised immune systems may put the body at greater risk for tumour growth, the presence of cancerous cells may also bring on immunosuppression.

How does depression effect immune functioning ?

Negative life events can elicit a negative mood that threatens immune function Ex. caregiving stress. Depression is associated with worse immune functioning and increased mortality risks of all patients.

Depression & cancer

Studies suggest:

- Depression predicts cancer mortality

-Pessimism = related to lower survival

-Negative mood states related to increased risk of contracting and dying of cancer

-Immunocompetence does not provide the whole explanation

In summary, it is safe to say that depression and other negative mood states are related to increased risk of contracting cancer and of dying from it once it is contracted. It is also likely that immunocompetence provides one explanation for these increased risks.

Depression & heart health

- Depression as possible risk factor for heart disease and related mortality

- Higher risk of first heart attack

-Higher risk with major depression

-Associated with reduced responsiveness of the immune system, reduced ability to deal with inflammation

What is the distinction between state and trait in psychology?

State refers to short-term conditions, while trait refers to enduring characteristics.

Why is the distinction between state and trait relevant in symptom reporting?

Increased symptom reporting could indicate chronic complaining rather than genuine symptom experience.

What did Cohen et al. (1995) find regarding state negative affect and immune systems?

High state negative affect is associated with compromised immune systems in a bi-directional manner.

How does PNI differentiate between acute and long-term stress effects on health?

Acute stress can enhance immune functioning, while long-term stress is usually detrimental.

What commonly occurs together with HIV infections?

Negative mood

How does depression affect T-helper cell activity in HIV+ individuals with high T-helper cell counts?

Depression is associated with lower T-helper cell activity.

What was the finding of the study involving 6000 HIV-positive individuals regarding depression?

The more years of depression, the higher the mortality rate.

What year was the study by Pence et al. that examined depression and mortality in HIV-positive individuals published?

2018

How does depression impact individuals with HIV?

Depression impacts all aspects of HIV.

what are the Proposed Biological Mechanisms?

There are Psychological states and traits which affect our health and illness via:

• Endocrine system - glucocorticoids

  • glucocorticoid resistance model: in response to chronic stress, glucocorticoid receptors become de-sensitized, fail to switch off, and chronic inflammation is the result.

  • the HPA axis continues to produce cortisol because the glucocorticoid receptors of immune cells no longer recognize a signal to switch off, leading to constant, mild inflammation.

• Sympathetic nervous system: reactivity hypothesis

• Immune system: affected by cortisol and activation of H P A axis

• Behaviour (e.g., depression affects sleep)

What are the 3 main Biological Mechanisms ?

1. Hypothalamic-Pituitary Adrenal axis: Chronic activation when stressor strong

2. Role of inflammation:

3. Effects of acute and long-term stress: Stress can lead to genomic changes that may either result in the up regulation or the down regulation of the immune system. That is why stress is linked to diseases that have increased immune system activity

explain the role of inflammation?

Cytocines: proteins that increase the body's capacity to produce inflammation; they help heal wounds and fight infection. Increase the body's capacity to produce inflammation

• Extreme stress can result in excessive inflammation

• Cortisol usually helps keep the inflammatory response in check so that it doesn't go overboard and cause problems. Unfortunately, stress reverses the effect of cortisol. Ultimately, severe stress results in excessive inflammation, which results in disease.