Anxiety Disorders, Autistic Disorder, ADHD, and Stress Disorders

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Chapter 17

• Anxiety Disorders, Autistic Disorder, ADHD, and
  Stress Disorders

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Anxiety Disorders

• A psychological disorder characterized by
  tension, overactivity of the ANS, expectation of
  an impending disaster, and continuous vigilance
  for danger
• Two types of anxiety disorders that appear to
  have biological causes
• Panic disorder
• Obsessive-compulsive disorder (OCD)

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Anxiety Disorders

• Panic disorder
• Characterized by episodic periods of symptoms
  such as shortness of breath, irregularities in
  heartbeat, and other autonomic symptoms,
  accompanied by intense fear
• Onset in young adulthood
• Victim often feels that he or she is going to die
• Between panic attacks, people with panic disorder
  suffer from anticipatory anxiety, the fear that
  another panic attack will strike
• Anticipatory anxiety often leads to agoraphobia,
  fear of being away from home or other protected
  places
• Disorder appears to be hereditary
• Strange genetic association between loose
  joints and panic disorder
• Patients with joint hypermobility syndrome are
  more likely to also have panic disorder than
  control subjects

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Anxiety Disorders

• Panic disorder
• Previously treated with a combo of behavior
  therapy and a benzodiazepine (which have strong
  anxiolytic, or anxiety reducing, effects)
• Benzodiazepine receptors are located on the GABAA
  receptor complex
• When benzo binds with receptor, it increases the
  sensitivity of the GABA binding site and produces
  an anxiolytic effect
• Anxiety disorders may be caused by decreased
  number of benzo receptors
• SSRIs used to treat panic disorder and OCD
• Cingulate, prefrontal, and anterior temporal
  cortices are involved (esp. decrease in activity
  during panic attacks)

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Anxiety Disorders

• Obsessive compulsive disorder (OCD)
• Suffer from obsessions (an unwanted thought or
  idea with which a person is preoccupied) and
  compulsions (the feeling that one is obliged to
  perform a behavior, even if one prefers not to do
  so)
• Incidence is 1-2 of population females gt males
  most commonly begins in young adulthood
• Compulsions fall into 4 categories counting,
  checking, cleaning, avoidance
• Some investigators believe that the compulsive
  behaviors are forms of species-typical behaviors
  (e.g. grooming, cleaning, and attention to
  sources of potential danger) that are released
  from normal control mechanisms by a brain
  dysfunction
• Could also be pathological examples of social
  rituals

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Anxiety Disorders

• OCD (cont)
• May have genetic origin
• OCD is associated with Tourettes syndrome (a
  neurological disorder characterized by tics and
  involuntary vocalizations and sometimes by
  compulsive uttering of obscenities and
  repetitions of the utterances of others) that
  appears in childhood
• Treatment for Tourettes includes
  antischizophrenic meds that block DA D2 receptors
• Many patients that have OCD have tics, and many
  patients with Tourettes have obsessions and
  compulsions
• Both disorders may be produced by the same
  genotype
• However, some brain damage (esp. to basal
  ganglia, cingulate gyrus, and prefrontal cortex)
  may lead to development of OCD

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Anxiety Disorders

• OCD (cont)
• Tic disorders ca be caused by a streptococcal
  infection, that can damage brain tissue
• Esp. by damage to basal ganglia
• Increased activity in frontal lobes and caudate
  nucleus in patients with OCD
• Some patients with severe OCD have been treated
  with cingulotomy (surgical destruction of the
  cingulum bundle, which connects the prefrontal
  cortex with the limbic system)
• Helps reduce intense anxiety and the symptoms of
  OCD
• Direct pathway (excitatory) in basal ganglia
  symptoms of OCD may be a result of overactivity
  in this pathway
• Most effective therapy for OCD is drug therapy
• All 5-HT reuptake blockers

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Autistic disorder

• 4 in every 10,000 infants born with this disorder
• A chronic disorder whose symptoms include failure
  to develop normal social relations with other
  people, impaired development of communicative
  ability, lack of imaginative ability, and
  repetitive, stereotyped movements
• Afflicts boys 3x more than girls
• Most autistic people are mentally retarded, but
  not all are
• Autistic disorder is one of several pervasive
  developmental disorders that have similar
  symptoms
• Aspergers syndrome less severe, do not include
  language impairment or cognitive deficits
• Retts disorder genetic disorder seen in
  girls accompanies and arrest of normal brain
  development during infancy
• Childhood disintegrative disorder show normal
  social and intellectual develop. until begin to
  regress sometime b/t ages 2-10 yrs.

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Autistic disorder

• Autism includes affective, cognitive and
  behavioral abnormalities
• Some investigators suggest that this may stem
  from brain abnormalities that prevent the person
  from forming a Theory of mind (i.e. unable to
  predict and explain the behavior of other humans
  in terms of their mental states)
• Imaging studies show great decrease in activity
  of fusiform face area (region of brain
  responsible for face recognition) in autistic
  individuals while looking at pictures of faces

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Autistic disorder

• Possible causes
• Heritability
• Some forms appear to be heritable
• 2-3 of siblings of autistic people also have
  autism
• Concordance rate for monozygotic twins is 70
• May be associated with specific genetic
  disorders Phenylketonuria (PKU) caused by
  inherited lack of an enzyme that converts
  phenylalanine (amino acid in diet) into tyrosine
  buildup of phenylalanine can cause disruption in
  brain development, and sometimes autism
• Brain pathology
• 20 of all cases of autism have definable
  biological causes, such as rubella, prenatal
  thalidomide, encephalitis, etc.
• Can result from a wide variety of factors that
  damage the brain or impair its development
• Thalidomide (a drug given to pregnant women in
  1960s to treat morning sickness) caused serious
  birth defects

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Attention-Deficit/Hyperactivity Disorder (ADHD)

• A disorder characterized by uninhibited
  responses, lack of sustained attention, and
  hyperactivity
• First shows itself in childhood
• Usually discovered at school
• DSMIV requires the presence of 6 or more of 9
  symptoms to diagnose
• e.g. difficulty in sustaining attention in tasks
  of play activities easily distracted by
  extraneous stimuli
• Diagnosis is often difficult
• Most common treatment is methylphenidate
  (Ritalin), which inhibits reuptake of DA

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Attention-Deficit/Hyperactivity Disorder (ADHD)

• Possible causes
• Strong evidence for hereditary factors in a
  persons likelihood of developing ADHD
• Symptoms may be a result of a delay of
  reinforcement gradient (i.e. the longer the
  delay of some type of reinforcement for a
  behavior, the less effective that reinforcement
  is)
• May be caused by underactivity of DA transmission
• Results from human and animal studies contradict
  each other not clear whether ADHD is caused by
  excessive number of DA transporters
• Imaging studies showed decreased blood volume in
  basal ganglia and cerebellar vermis of boys with
  ADHD

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Stress Disorders

• Stress a general, imprecise term that can refer
  either to a stress response or to a stressor
• Stressor a stimulus (or situation) that
  produces a stress response
• Stress response a physiological reaction caused
  by the perception of aversive or threatening
  situations
• The physiological responses that accompany the
  neg. emotions prepare us to threaten rivals or
  fight them or to run away
• Fight-or-flight response a species-typical
  response preparatory to fighting or fleeing
  thought to be responsible for sme of the
  deleterious effects of stressful situations on
  health

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Stress Disorders

• Physiology of the stress response
• Autonomic and endocrine responses to emotions
  sympathetic branch of ANS becomes active, and
  adrenal glands secrete epinephrine, NE and
  steroid stress hormones
• Epinephrine affects glucose metabolism, causing
  nutrients stored in muscles to become available
  to provide energy for strenuous exercise
• Some of the behavioral and physiological
  responses produced by aversive stimuli appear to
  be mediated by NE neurons
• The other stress-related hormone is cortisol, a
  glucocorticoid (a hormone that has effects on
  metabolism) secreted by the adrenal cortex
• Secretion of glucocorticoids is controlled by
  paraventricular nucleus of the hypothalamus (PVN)
• The neurons of the PVN secrete a peptide called
  corticotropin-releasing hormone (CRH) which
  stimulates the anterior pituitary to secrete
  adrenocorticotropic hormone (ACTH), which enters
  the bloodstream and stimulates the adrenal cortex
  to secrete glucocorticoids

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Stress Disorders

• Health effects of long-term stress
• Many studies of humans who have been subjected to
  stressful situations have found evidence of ill
  health
• Hans Selye, a pioneer in the study of stress,
  suggested that most of these harmful effects from
  stress were produced by prolonged secretion of
  glucocorticoids
• Effects include increased blood pressure, damage
  to muscle tissue, steroid diabetes, etc.
• Research with animals shows that long-term
  exposure to glucocorticoids destroys neurons in
  field CA1 of hippocampus, affecting memory in the
  long-term
• Severe stress appears to cause brain damage in
  humans as well

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Stress Disorders

• Posttraumatic Stress Disorder (PTSD)
• A psychological disorder caused by exposure to a
  situation of extreme danger and stress
• Symptoms include recurrent dreams or
  recollections
• Can interfere with social activities and cause a
  feeling of hopelessness
• Genetic factors play a role in a persons
  susceptibility to develop PTSD and to be involved
  in an event that may cause PTSD
• Found hippocampal damage in patients with PTSD
• However, found lower levels of cortisol, instead
  of assumed higher levels (in order to cause brain
  damage)
• Exposure to stress increases the number and
  sensitivity of glucocorticoid receptors in the
  hypothalamus and anterior pituitary
• Instead, high levels of CRH may play a role in
  the development of PTSD

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Stress Disorders

• Stress and cardiovascular disease
• The degree to which people react to potential
  stressors may affect the likelihood that they
  will suffer from cardiovascular disease
• Individuals who had hyperreacted to a stress test
  earlier in life were more likely to have high
  blood pressure later in life
• Studies with monkeys demonstrate that individual
  differences in emotional reactivity are a risk
  factor for cardiovascular disease
• The animals that showed strongest negative
  reactions to a threat eventually developed higher
  rates of coronary artery disease
• Acute stress can also affect cardiovascular
  disease
• Can cause constriction of coronary arteries,
  arrhythmias in heartbeat, stimulation of platelet
  function (causes forming of clots), and increased
  viscosity of the blood

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Stress Disorders

• The coping response
• One of the most important variables that
  determines whether an aversive stimuli will cause
  a stress reaction is the degree to which the
  stimulus can be controlled
• Animals can learn coping responses in order to
  avoid aversive stimuli, and thus reduce their
  stress response
• The opportunity to make a coping response
  decreases the negative impact of stress on the
  hippocmpus

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Stress Disorders

• Psychoneuroimmunology
• Stress response can impair the function of the
  immune system
• Study of interactions b/t the immune system and
  behavior is called psychoneuroimmunology
• The immune system
• Function is to protect us from infection
• 2 types of reactions occur when the body is
  invaded by foreign organisms
• Chemically mediated involves antibodies
  (proteins produced to seek out and destroy
  antigens present on invading organisms)
• One type of antibody is released into circulation
  by B-lymphocytes, which develop in bone marrow
  the antibodies released are called
  immunoglobulins, which are chains of proteins
  that help destroy invading microorganisms
• Cell mediated produced by T-lymphocytes, white
  blood cells that originate in thymus gland
• Communication b/t cells is accomplished by
  cytokines

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Stress Disorders

• Psychoneuroimmunology
• Neural control of the immune system
• Stress increases the secretion of
  glucocorticoids, and these hormones directly
  suppress the activity of the immune system
• Individuals with severe stress showed lowered
  levels of antibodies
• This suppression is largely mediated by
  glucocorticoids, which are mediated by neural
  activity
• Stress and infectious disease
• Stress-producing events can increase a persons
  susceptibility to illness
• Since the immune system is suppressed, a person
  is more likely to develop an illness after times
  of stress