Psychoneuroimmunology PNI

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Psychoneuroimmunology(PNI)

• By Fabiola Tatone
• EPI 6181, December 4, 2006

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Psychoneuroimmunology (PNI) What is it?

• The field that studies the interactions between
  the central nervous system, the endocrine system
  and the immune system the impact of
  behavior/stress on these interactions and the
  implications for health of these interactions -
  Ronald Glaser
• From 1919, stress was noted to influence the
  progression of pulmonary tuberculosis.
• In 1974, Robert Ader conducted the first
  experiments showing that the brain directly
  influences the immune system by using classical
  conditioning in rats. Ader paired an inert
  substance such as saccharine (the Conditioned
  Stimulus) with an immunosuppressive substance
  that decreases T-lymphocytes, cyclophosphamide
  (the Unconditioned Stimulus) and demonstrated
  that the harmless substance caused
  immunosuppression and rats died.

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How psychological factors affect our immune
system vice-versa

• The nervous system affects the endocrine system
  via the pituitary gland, controlling hormone
  secretion.
• The endocrine system modulates the immune system
  through the hormones secreted by the pituitary
  and adrenal glands. This hypothalamus-pituitary-ad
  renal axis (HPA) plays a central role, as immune
  cells are equipped with receptors for HPA
  molecules, and are altered in number, function,
  and distribution as a result of the hormones
  secreted.
• Through the autonomic nervous system, the nervous
  system also has direct effects on the immune
  system via the thymus gland, the spleen, and bone
  marrow.
• Cytokines (communication molecules of the immune
  system), are secreted by immune system cells and
  are one of the components that fight foreign
  invaders, regulate the production of immune cells
  and also impact the central nervous system and
  the HPA axis.
• Cytokines also drive our physiological illness
  response, affecting our mood, fever, eating, and
  sleeping patterns, along with other associated
  behaviours. This response to illness is evident
  at the neuronal level, demonstrating changes in
  neuronal firing rates and neurotransmitter
  turnover when presented with an immune challenge
  this provides evidence for a bi-directional
  circuit.
• Thus, yes, its complex!
• CNS
• Endocrine Immune
• System System

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Stress the Immune System

• In laboratory studies, short-term stressors such
  as making a speech, are shown to inhibit an
  effective immune system response in as little as
  5 minutes.
• Longitudinal studies show that individuals who
  experience significant stressors at one point or
  another have increased rates of illnesses and
  long-term immune suppression over time this
  association is present even after controlling for
  confounding factors such as smoking and substance
  abuse.
• The effect of stress has been investigated for
  the most part as a main effect, however other
  studies also show that it may interact with other
  factors (e.g. personality) in its effect on
  illness.

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Stress Immune function Taken from J.L.Jarrys
(2002) Health Psychology slides at U.of T.
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Mood the Immune System

• Negative emotions induced by stress also impact
  the immune system.
• Studies show that negative emotions such as
  sadness, grief, and helplessness, suppress immune
  function, such that individuals who are ill are 3
  times more likely to die as a result of their
  illness if they are depressed, in comparison to
  those who are ill and not depressed.
• Studies on the effects of mood on cancer have
  shown that cancer patients who are depressed have
  lower natural killer cell activity (NKCA) in
  comparison to their non-depressed counterparts.
  These findings come from 2 types of longitudinal
  studies 1) studies following cancer-free people
  over time, measuring their mood and possible
  cancer onset 2) studies following individuals
  already diagnosed with cancer and monitoring how
  their mood is associated with cancer progression.

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Social Support the Immune System

• Emotional and instrumental support have also been
  shown to relate to proper immune function.
• Theorell et al. (1995) found that HIV-positive
  men with low levels of social support had a more
  rapid decline in T-helper cell counts over a
  period of 5 years than did HIV-positive men with
  high levels of social support.

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Effects on Immune Function

• Other factors including, anxiety, sleep
  deprivation, abortion, divorce, family illness,
  unemployment, personality, coping style,
  psychiatric illness, and war have also been shown
  to impact immune function. (summarized by Reilly
  McCabe, 1997).
• Conversely, the immune system and disease can be
  positively influenced by relaxation, humour,
  hypnosis, meditation, and positive attitudes.
  These techniques induce a physiological
  relaxation response (as opposed to the stress
  fight-or-flight response), reducing blood
  pressure, respiratory rate, heart rate, etc.

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What does this mean for health practice?

• Clinical Interventions
• Therapeutic interventions such as hypnosis,
  psychotherapy, and stress management techniques
  have demonstrated benefits in alleviating
  symptoms of chronic illnesses such as cancer, and
  latent viral infections such as herpes.
  Immunological changes are also documented as a
  result of these interventions.
• Women with breast cancer have seen extended
  survival rates as a result of participation in
  group therapy or self hypnosis.
• However, it is important to note that direct
  associations are difficult to observe as a result
  of confounding factors such as changes in diet,
  lifestyle, and medical treatments.
• Nonetheless, this does not discount the potential
  benefits obtained by considering psychological,
  behavioural, and emotional interventions in
  addition to traditional medical treatments when
  targeting an illness. As Roger Sturrock once
  mentioned
• If you settle the patient, the illness then
  often settles.
• However, this in no way implies that our
  illnesses are purely a result of our poor
  stress-management techniques. Stress management
  (as an example) is just an important part of the
  dynamic picture.

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The Placebo Effect

• Many argue that the therapeutic interventions
  described are simply a placebo effect a bodys
  ability to heal itself as a result of the
  confidence in an unknowingly inert intervention
  (e.g. a sugar pill).
• The placebo effect is also defined as a change
  in a patients illness attributable to the
  symbolic import of a treatment rather than a
  specific pharmacologic or physiologic property.
• Benefits obtained through placebos have
  implicated the autonomic nervous system (with
  improvements in hypertension, cardiac pain, and
  headaches), the endocrine system (diabetes and
  menstrual pain), and the immune system (colds,
  asthma, and cancer).

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The Placebo Effect (contd)

• The placebo effect is considered by many to
  represent that an illness was all in your mind.
  However, although the placebo may be chemically
  inactive, its effects are evident beyond the
  psyche.
• 1) Through patients confidence in a treatment,
  placebos have been shown to reduce stress,
  anxiety, and depression, all which have been
  reviewed to associate with illness.
• 2) Placebo treatments may also work as
  conditioned stimuli, similar to Aders
  experiments with saccharine in rats.
• 3) The placebo response may also act directly on
  the CNS with the release of the bodys natural
  pain killers and narcotics (e.g. endorphins and
  enkephalins).
• Thus, although the beliefs may be all in the
  mind, the effects of this belief alter an
  individuals biochemistry to mimic the effects of
  an active drug.
• However, it is difficult to study the exact
  physiological mechanisms of placebo effect as its
  effectiveness also depends on the patients faith
  in the treatment, reduction of anxiety, and
  conditioning no individual has the same response
  to a given placebo. Just the same, the
  therapeutic potential of placebos merit important
  consideration.

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Bi-directional Interactions between the Brain and
Nervous System

• Evidence suggesting the presence of
  bi-directional pathways between the brain and
  immune system cannot be ignored.
• The two pathways connecting these systems are
  primarily the autonomic nervous system and the
  HPA axis, and these communicate via chemical
  messengers from nerve cells, endocrine organs,
  and immune cells.
• Although most research has focused on how the
  sympathetic nervous system and HPA axis affect
  the immune system, there is evidence that the
  reverse also occurs. The immune system impacts
  the nervous system inducing sickness behaviour
  through fever, loss of appetite, an increase need
  for sleep, etc. This results from active immune
  cells releasing cytokines, sending back messages
  through the HPA and to the brain.
• The implication of this bi-directional pathway
  suggests the possibility for future chemical
  interventions to obstruct these chemical pathways
  so that, for example, stressful situations will
  be prevented from interfering with our immune
  function, and sickness behaviour can be better
  managed by interfering with its feed-back loop
  as well.
• Does this all mean that people of lower SES, who
  tend to be more likely to experience stressful
  life circumstances, will no longer show
  disparities in health once we find a way to block
  these psychoneuroimmunological communication
  routes? That will be left to us future
  researchers to discover!

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References

• Azar B. A new take on psychoneuroimmunology.
  Monitor on Psychology, 200132(11). URL
  http//www.apa.org/monitor/dec01/anewtake.html
• Jarry JL. Psychoneuroimmunology PPT-slides.
  Health Psychology (PSY333). Dept. of Psych.
  University of Toronto 2002.
• Kinser PA. Therapeutic placebo effect A
  mind/body connection. 1999. URL
  http//serendip.brynmawr.edu/bb/neuro/neuro99/web1
  /Kinser.html
• Kinser P. Psychoneuroimmunology and natural
  healing by the brain. 1999. URL
  http//serendip.brynmawr.edu/bb/neuro/neuro99/web2
  /Kinser.html
• Reilly D., McCabe D. Creative consulting
  Psychoneuroimmunlogy, the mindbody. URL
  http//www.studentbmj.com/back_issues/0402/educati
  on/97.html
• Wachterman M. Psychoneuroimmunology
  Bi-directional interactions between the brain and
  the nervous system. 2000. URL
  http//serendip.brynmawr.edu/bb/neuro/neuro00/web1
  /Wachterman.html