The Effects of Stress And The Brain


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  • Individual differences in stress response are genetically influenced
  • statistical correlation between violence and the levels of MAO assayed in blood platelets. Lower MAO activity is found in violent criminals, both male and female. The gene for monoamine oxidase A (MAO-A) is located on the X chromosome and individuals with deletions and point mutations are known. Thus MAO-A defects are sex-linked. Alterations in the MAO-A gene result in marked changes in monoamine metabolism and are associated with variable cognitive deficits and behavioral changes in both humans and transgenic mice. The incidence of severe MAO-A defects is extremely low, and unlikely to account for more than a tiny proportion of criminal behavior. On the other hand, it is conceivable that the wider correlation between MAO levels and violent crime is due to genetic alterations that result in moderate reduction of monoamine oxidase activity.
  • Individual differences in stress responses also appear to be related to maternal care and early attachment
  • An important factor in all healthy coping skills is the idea of control
  • Researchers have studied the “belief hormonal response” triggered even with placebos and discovered that “belief” turns on endorphins
  • The Effects of Stress And The Brain

    1. 1. Understanding the Impact of Stress on Brain Development and Learning
    2. 2.  Merriam-Webster define stress as: A physical, chemical or emotional factor that causes bodily or mental tension
    3. 3.  Acute stress is general short-term with a clearly defined beginning and end  Chronic stress is long-term and prolonged stress with no clear ending  Both acute and chronic stress trigger the physiological stress response
    4. 4.  Triggering of the sympathetic nervous system which prepares the body to deal with perceived threat by: ◦ Increase of heart rate and blood pressure ◦ Increase of cortisol – “stress” hormone which has anti-inflammatory and immunosuppressive properties ◦ Decline of parasympathetic activity which regulates “automatic” bodily functions and maintains homestasis
    5. 5. ◦ Shorter form of the serotonin transporter is associated with vulnerability to increased response to stress by developing depressive illness and alcoholism
    6. 6. ◦ An allele of the monoamine oxidase A gene result in more vulnerability to abuse in childhood, increased risk of becoming an abuser & show antisocial behaviors.
    7. 7.  Early abuse can result in life long emotional reactivity and stress hormone reactivity – both associated with cognitive decline and shorter lifespan in animal studies
    8. 8.  Stress reduction in infants can be influenced by maternal bonding through a variety of factors ◦ Physical proximity ◦ Modeling  Early patterns “hard-wire” the stress response –critical period during 1st nine months
    9. 9.  Males most typically mirror the fight or flight response  Females engage fight or flight AND befriend
    10. 10.  There is an inverted relationship between learning and levels of cortisol  During acute stress, higher levels of cortisol result in: ◦ Enhanced immunity ◦ Enhanced memory During chronic or prolonged stress, the increased levels of cortisol result in: ◦ lower immune response ◦ Impaired cognitive functioning
    11. 11.  The Hippocampus is the brain structure primarily responsible for learning and memory  The Hippocampus is highly sensitive and malleable  Cortisol decreases and retracts the dendritic growth in the hippocampal area
    12. 12.  Within the Hippocampus, is the dentate gyrus, a structure which seems to play a role in the memory of sequences of events  It has high plasticity and is constantly producing new neurons, even throughout adult life.  Certain types of stress suppress neurogenesis and cell survival in the dentate gyrus
    13. 13.  Cortisol inhibits long- term potentiation – cell sensitivity in communication  Adolescent brain is more receptive to long-term potentiation without interference
    14. 14.  Repeated or chronic stress causes dendritic shortening in the medial prefrontal cortex  The results in impairment in attention set shifting
    15. 15.  Both acute and chronic stress produce dendritic growth in neurons in the amygdala.  The results of include: ◦ Increases anxiety ◦ Increased aggression
    16. 16.  In animal research, chronic stress causes atrophy of neurons in the hippocampus and prefrontal cortex  and  Hypertrophy of neurons in the amygdala  Results: ◦ Decreased learning and memory ◦ Increased anxiety and aggression
    17. 17.  The results from animal studies are mirrored in humans through a loss of hippocampal volume and an increase in amygdala volume in MRI studies  PET scans also demonstrate altered patterns of activity in the related brain areas during stress
    18. 18.  Learn stress management – variety of techniques  Problem-focused – changing the stressor  Emotion focused – changes our response to the stressor
    19. 19.  Physical  Cognitive  Emotional  Behavioral
    20. 20.  Physical Techniques: Exercise Meditation Relaxation
    21. 21.  Cognitive Techniques: Social Comparisons Re-Evaluation Distraction
    22. 22.  Emotional Techniques: Social Support Release Laughter
    23. 23.  Behavioral Techniques: Helping Others
    24. 24.  Optimism is associated with lower cortisol production and higher heart rate variability (showing higher parasympathetic activity)  Optimistic people are, on average, healthier and live longer than pessimistic people  Optimistic people have higher levels of life satisfaction
    25. 25.  Poor self-esteem has debilitating effects: ◦ Increased levels of cortisol ◦ Inability to regulate cortisol levels under stress ◦ 12-13% loss of hippocampal volume
    26. 26.  Improve sleep quality and quantity  Have a good social support system  Maintain a positive outlook on life  Maintain a healthy diet  Avoid smoking  Regularly exercise – moderate activity  Build positive self-esteem  Learn successful stress management
    27. 27.  McEwen, B.S. Protective and damaging effects of stress mediators: central role of the brain. New England Journal of Medicine. 1998, 338: 171-179
    28. 28. Q&A Robin Donaldson,