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  • electromyogram (EMG)

PPT PPT Presentation Transcript

  • Stress Disorders, Sleep Disorders
  • 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
  • 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)
  • 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
  • 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
  • 1. Sufficient sensory information is present for assessment. Vermetten & Bremmer, 2002
  • 2. Assessment based on access to prior experience. Vermetten & Bremmer, 2002
  • 3. Encode memory of (potential) threat. Vermetten & Bremmer, 2002
  • 4. Access to neuroendocrine, autonomic, motor responses. Vermetten & Bremmer, 2002
  • 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
  • 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
  • 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.
  • 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.
  • 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.
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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)
  • 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)
  • Sleep Disorders
  • 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
  • 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
  • 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
  • What is normal sleep?
  • 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)
  • 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)
  • 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)
  • 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
  • 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
  • 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
  • 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)