24 Psychoneuroimmunology Flashcards
What is the main organ of the immune system?
The white blood cells themselves
When an immune cell detects something is wrong it releases messenger molecules, generally called…
Cytokines - these include interleukins, prostoglandins yada yada
How can it be demonstrated that mental health affects immune response?
Higher rates of illness in patients with mental health issues.
Cancer death rates 39% in depressed patients
50% higher risk of cancer in SZ
What did Ader & Cohen (1975) demonstrate about immune suppression?
Immune response can be conditioned -> placebo effect. Brain can suppress immune function.
First paired saccharine CS with immune-suppressant drug cyclophosphamide
Then saccharine alone was able to suppress immune system.
How can conditioned immune suppression enable tissue transplant?
If immune suppression is conditioned –with anti-tissue-rejection drug cyclosporine A –it takes longer for body to reject tissue grafts.
What evidence is there that immune stimulation can also be conditioned?
Administration of allergenic substance (bovine serum albumin (BSA)) was paired with sprays of almond essence in guinea pigs. After repeated trials, almond essence alone was capable of inducing allergic response. Creation of psychogenic illness.
What is the immune effect of cortisol?
Massive immuno-suppressant effect, may be responsible for immune response in lab tests
How does stress cause immune response?
Under stress, brain increases production of glutocorticoids (such as cortisol), which has suppressant function on immune response
How does the sympathetic and parasympathetic nervous system affect immune response?
NTs released by the SNS and PNS are mainly catecholamines –adrenaline, noradrenaline –and immune cells have receptors for these NTs. Thus the autonomic nervous system can regulate immune response.
What is neurogenic inflammation?
Peripheral nerves can release substances from their tips - such as substance P from pain sensory nerves - that can cause inflammation
What are the 3 main ways the brain can tune the immune response?
- Release hormones through the pituitary and other glands
- Autonomic nervous system can suppress or increase the activity of immune cells in the periphery
- Pain sensory nerves themselves have neurogenic effect on inflammatory processes in tissue
What relation did Cohen et al. 1991 between stress levels and infectious illnesses in people?
Strong linear relationship
How does cortisol reactivity (how much cortisol you release when stressed) predict probability of getting a cold?
If few negative life events, little difference between low-and high-cortisol-reactive people;
If many negative life events, high-cortisol-reactive people have drastically higher likelihood of having a cold
What changes in physiology do cytokines bring about when you’re sick?
Change blood pressure - how much getting to tissues, quantity of iron in blood, more local inflammation… range of things to help body get rid ofbacteria or viruses
What relationship is there between stimulation of immune system and the central nervous system?
An immune response stimulates glutocorticoid response from the central nervous system. It also stimulates sympathetic activation resulting in fever.
What is characteristic cluster of symptoms for sick people?
Loss of appetite - anorexic effect Loss in body weight - anorexic effect Increase in body temperature Tendency to conserve heat Reduce amount of exploration Sleep more Cognitive impairment - can't think straight Affective changes - anhedonia, depressed, stressed
What is the cytokine theory of depression?
Given that immune response produces such similar symptoms to depression, there may be etiological link between the two
How does the CNS detect immune activity?
Detection of cytokines by peripheral nerves such as the vagal nerve
Diffusion of cytokines from immune cells into the CNS
Production of cytokines in the brain in response to non-immune danger signals
How can brain produce immune response without infection?
In response to danger signals - threat, stress - brain itself will start releasing cytokines which give rise to behavioural and endocrine responses - sleepiness, fever, depression, anorexia etc.
Why do we have immune responses?
Sickness behaviours are adaptive:
- Heat/energy conservation
- fevers help recuperation
- more resources for immune cells - Minimising harm - stay in bed
Why is sickness response like hunger and thirst?
The sickness response amounts to an adaptive motivational state - organises an individual to look after themselves
What did Dantzer et al. 2002 study of mother rats demonstrate about motivational state of sickness?
If low ambient temperature, mother will rebuild nest for pups when sick
If high ambient temperature, mother will not rebuild nest for pups
Sickness as motivational state organises behaviour differently according to context
How does behaviour contribute to health? 3 things
- Recuperation from acute injury or infection
- Prevention of future injury/infection:
- hygiene (personal and public)
- lifestyle and diet
- utilising health services - Many diseases require behavioural interventions as part of the cure - obesity, alcoholism etc.
In what way are many of society’s health problems psychological?
Metabolic diseases - obesity, diabetes - are actually psych problems - problems caused by behaviour. Best treatment is psychological intervention. GPs do this – “exercise more!” – but don’t follow up.
What are the effects of exercise on health?
Reduces: metabolic diseases chronic pain depression anxiety cognitive impairments due to aging (eg. Alzheimer's)
Improves recovery for cancer treatment - more likely to survive 5 years after cancer treatment
How does exercise affect stress reactivity?
Switches people from high-cortisol reactivity to low-cortisol reactivity. Has regulatory effects on endocrine system.
Does having a positive attitude speed recovery from disease?
No. People with positive attitude are less likely to seek help. Pop psych can undermine contemporary medicine.
What can a positive attitude to do help?
If you’re dying it improves quality of life. So useful in palliative context.
