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  • electromyogram (EMG)
  • Transcript

    • 1. Stress Disorders, Sleep Disorders
    • 2. Stress Disorders
      • Stress (response) : physiological and behavioural reaction caused by the perception of aversive or threatening stimuli (Cannon, 1921).
      • Stressors : Environmental triggers of stress
      • PTSD requires an identifiable stressor for diagnosis
      • Often the association between the stressor and the stress response is not clear
    • 3. Stress Response
      • Fight or flight response: mobilization of resources to prepare us to face stressors
        • Effects of the Hypothalamic-Pituitary-Adrenal axis
      • Mobilization of energy in face of the stressors includes:
      • Activation of sympathetic nervous system
        • increased heart rate, increased muscular contractions, increased blood pressure, decreased digestion/metabolism
      • Adrenal hormones are released
        • Epinephrine
        • Norepinephrine (activation of NE receptors in brain)
        • Steroid stress hormones (cortisol)
    • 4. Stress Response
      • 1. Norepinephrine
        • Stressful situations (e.g. social isolation in rats) will increase release of NE
        • hypothalamus, frontal cortex, and lateral basal forebrain including portions of amygdala (Yokoo et al., 1990, Cenci et al., 1992; van Bockstaele et al., 2001)
        • Downregulation of the alpha-2 receptor in response to hight NE levels
      • 2. Serotonin
        • 5HT is decreased
        • Raphe nucleus, frontal areas involved in extinction
    • 5. Stress Response
      • 3. Glucocorticoids and corticotropin releasing hormone (CRH)
      • Receptors throughout the brain (and rest of body)
      • Controlled by the hypothalamus, CRH serves as a neuromodulator in the limbic system, periaqueductal gray matter, locus coeruleus, and amygdala
      • Injection of CRH into rats’ brains induces fear reactions (Britton et al., 1982)
      • Antagonists of CRH reduce anxiety caused by stressors (Heinrichs et al., 1994)
      • Heightened activation of sympathetic nervous system
    • 6. 1. Sufficient sensory information is present for assessment. Vermetten & Bremmer, 2002
    • 7. 2. Assessment based on access to prior experience. Vermetten & Bremmer, 2002
    • 8. 3. Encode memory of (potential) threat. Vermetten & Bremmer, 2002
    • 9. 4. Access to neuroendocrine, autonomic, motor responses. Vermetten & Bremmer, 2002
    • 10. PTSD: Prevalence, Info
      • Prevalence: 5-10% (U.S), higher in war-torn areas
      • Three themes of PTSD:
      • Re-experiencing of stressful event
      • Avoidance of stimuli
      • Persistent, increased arousal
    • 11. PTSD: Prevalence, Info
      • In adults, traumatic events occur more often to men, but PTSD is 4 times more common in women (Fullerton et al., 2001)
      • In children:
      • Loss of acquired language skills
      • Regression of toilet training
      • Somatic complaints (stomachaches or headaches)
      • Delayed onset of PTSD often occurs for chronic abuse
    • 12. PTSD: DSM-IV Criteria
      • The person has been exposed to a traumatic event in which both of the following have been present:
      • (1) the person experienced, witnessed, or was confronted with an event or events that involved actual or threatened death or serious injury, or a threat to the physical integrity of self or others
      • (2) the person's response involved intense fear, helplessness, or horror.
      • Note: In children, this may be expressed instead by disorganized or agitated behavior.
    • 13. PTSD: DSM-IV Criteria
      • B. The traumatic event is persistently re-experienced in one (or more) of the following ways:
      • recurrent and intrusive distressing recollections of the event, including images, thoughts, or perceptions.
      • Note: In young children, repetitive play may occur in which themes or aspects of the trauma are expressed.
      • (2) recurrent distressing dreams of the event.
      • Note: In children, there may be frightening dreams without recognizable content.
    • 14. PTSD: DSM-IV Criteria
      • (3) acting or feeling as if the traumatic event were recurring
      • sense of reliving the experience
      • illusions, hallucinations, and dissociative flashback episodes
      • young children: trauma-specific reenactment may occur.
      • (4) intense psychological distress at exposure to internal or external cues that symbolize or resemble an aspect of the traumatic event.
      • (5) physiological reactivity on exposure to internal or external cues that symbolize or resemble an aspect of the traumatic event.
    • 15. PTSD: DSM-IV Criteria
      • C. Persistent avoidance of stimuli associated with the trauma and numbing of general responsiveness (three or more of the following):
      • (1) efforts to avoid thoughts, feelings, or conversations associated with the trauma
      • (2) efforts to avoid activities, places, or people that arouse recollections of the trauma
      • (3) inability to recall an important aspect of the trauma
      • (4) markedly diminished interest or participation in significant activities
    • 16. PTSD: DSM-IV Criteria
      • (5) feeling of detachment or estrangement from others
      • (6) restricted range of affect
      • unable to have loving feelings
      • (7) sense of a foreshortened future
      • does not expect to have a career, marriage, children, or a normal life span
    • 17. PTSD: DSM-IV Criteria
      • D. Persistent symptoms of increased arousal (not present before the trauma), as indicated by two (or more) of the following:
      • (1) difficulty falling or staying asleep
      • (2) irritability or outbursts of anger
      • (3) difficulty concentrating
      • (4) hypervigilance
      • (5) exaggerated startle response
    • 18. PTSD: DSM-IV Criteria
      • E. Duration of the disturbance is more than one month.
      • F. The disturbance causes clinically significant distress or impairment in social, occupational, or other important areas of functioning.
      • Specify if:
      • Acute: if duration of symptoms is less than 3 months
      • Chronic: if duration of symptoms is 3 months or more
      • Specify if:
      • With Delayed Onset: if onset of symptoms is at least 6 month
    • 19. Health effects of long term stress
      • Chronic stress is thought to be most problematic for long-term health
      • Acute traumatic stress , in a few cases, may be equally as devastating
      • (e.g. war, natural disasters, rape, witnessing murder)
        • Exacerbation of initial traumatic event
    • 20. Health effects of long term stress
      • Selye (1976) – long-term effects of stress are caused by chronic release of glucocorticoids
        • Increased blood pressure
        • Damage to muscle tissue
        • Steroid diabetes
        • Infertility
        • Inhibition of growth
        • Inhibition of inflammatory responses
        • Suppression of immune system
      • Loss of brain tissue
        • Elevated levels of CRH in women and men with PTSD (Yehuda, 2001)
    • 21. Neuropathology
      • volume loss of hippocampus in veterans with combat-induced PTSD (Bremner et al., 1995)
      • brain degeneration occurred in people who had been subjected to torture (Jensen et al., 1982) – note: not by experimenters
      • Loss is proportional to amount of combat exposure (Gurvits et al. 1996)
      • Similar effects in those exposed to severe childhood abuse (Bremner et al, 1999)
    • 22. Sleep Disorders
    • 23. Sleep Disorders
      • 1 in 8 Canadians suffer from a Sleep Disorder
      • May or may not be related to stress
      • May be related to undersleeping or oversleeping
      • Often comorbid with anxiety or depression
      • No age limits for definition
      • Often undiagnosed or untreated for years
      • Can have profound impact on physical and mental health
    • 24. What is normal sleep?
      • Waking
      • Beta waves: 13-40 Hz, low amplitude, asynchronous
      • Alpha waves: 8-13 Hz, higher amplitude (when meditative or relaxed).
      • 2. Stages 1 and 2 (Light sleep)
      • Theta waves: 4-7 Hz
      • May not be aware that you fell asleep
      • 3. Stages 3 and 4 (Heavy sleep)
      • Delta waves: < 4Hz
      • Sleep walking and talking
    • 25. What is normal sleep?
      • 4. Rapid eye movement (REM) sleep
      • Return of alpha and beta activity, like waking states
      • Darting eye movements
      • Dramatic loss of muscle tone--effectively paralyzed
      • Dreaming
      • Stage 1 to REM = 90 minutes
      • As night progresses, amount of REM sleep increases and stage 3-4 sleep decreases
    • 26. What is normal sleep?
    • 27. Disorders of sleep
      • Insomnia
      • Narcolepsy
      • REM Sleep Behaviour Disorder
      • Problems associated with slow wave sleep
      • Inability to sleep at night produces many of the same symptoms as the stress response--sleep is critical for neural “recovery”
      • Hallmark of all sleep disorders is an inability to maintain normal wakefulness during the day: Excessive daytime sleepiness (EDS)
    • 28. Insomnia
      • Feeling that you are not getting enough sleep, often associated with anxiety
      • May be difficulty falling asleep or early waking, often associated with depression
      • Hard to define as people differ in sleep needs
      • Often treated with drugs although majority of patients do not undergo a sleep study
      • Most drugs are barbiturates which affect GABA receptors (perhaps in reticular activating formation)
    • 29. Narcolepsy
      • Neurological disorder characterized by sleep at inappropriate times (sleep attack)
        • Overwhelming urge to sleep particularly in monotonous conditions
        • Sleep appears normal and lasts 2-5 minutes
        • Person (temporarily) feels refreshed
      • Cataplexy : muscular paralysis while fully awake (similar to paralysis during REM)
        • Usually triggered by strong emotion or sudden physical effort
      • Hypnagogic hallucinations: seeing and hearing things as one is falling asleep.
      • Often skip slow wave sleep at night and move directly to REM from waking
      • Caused by low levels or absence of a peptide hypocretin in lateral hypothalamus (Saper et al., 2001)
    • 30. REM Sleep Behaviour Disorder
      • Typically we are paralyzed during REM sleep
      • In some people, this paralysis does not occur, and they act out their dreams without awareness
      • Not necessarily the same as sleepwalking, although this may be a component
      • Associated with neurodegenerative disorders (such as Parkinson’s)
      • Can be associated with brain damage to pons, reticular activating formation (Culebras and Moore, 1989)
      • Symptoms are opposite to those of cataplexy
    • 31. Slow-wave sleep
      • Usually occur during stage 4, when a person is difficult to rouse but not dreaming
      • Include:
        • Bedwetting (nocturnal enuresis)
        • Sleepwalking (somnambulism)
        • Night terrors (pavor nocturnis)
      • All of these tend to occur more frequently in children – they usually grow out of these
      • No association with other mental health disorders
      • Not sure of neurobiology as it is difficult to do sleep studies with children
    • 32. Neuropathology
      • Wake-sleep cycles are regulated by brainstem structures
      • Thalamic nuclei (which receive direct visual input from the LGN)
      • Suprachiasmatic nucleus: circadian clock
      • Ventrolateral preoptic nucleus: wakefulness and vigilance
      • 2. Other areas
      • Raphe nucleus (pons): general arousal
      • Locus coeruleus: vigilance, arousal
    • 33. Neuropathology
      • A host of different medications are used to increase vigilance and altertness
      • Epinephrine and its agonists
      • Other monoaminergic agonists: Methylphenidate
      • Acetylcholine antagonists: Caffeine
      • Most medications with sedative effects focus on increasing GABA concentrations (benzodiazepines, barbiturates)

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