AA

Chapter 10: Childhood Disorders

In This Chapter…

  • Autism
  • Attention Deficit Hyperactivity Disorder
  • Down Syndrome
  • Dyslexia

Autism

  • ASD (Autism Spectrum Disorders) are characterized by
    • impaired social skills
    • verbal & nonverbal communication difficulties
    • narrow obsessive interests or repetitive behaviors
  • Symptoms of ASD include:
    • intellectual disabilities
    • seizures
    • gastrointestinal problems
    • Increase due to the detection of subtler autism and an actual increase
  • ASD is thought to be highly genetic
    • 100+ genes are linked to an increased risk for autism
    • There is no single genetic or biochemical marker for autism
  • ASD is typically diagnosed based on behavior in children around 3 years old
  • ASD-affected children at 1-2 years old show abnormal growth of the brain
    • This indicates that brain development has gone awry
    • Also a potential marker for early evaluation
    • These brain alterations are subtle
  • Speculation: abnormal development in regions of the brain involved with language, cognition, and social communication leads to abnormal connections with other parts of the brain
  • No cure or drugs for the major symptoms of ASD
  • Good response to specialized behavioral therapies based on learning theory
    • Therapy is guided by an increased understanding of how the brain normally reacts to learning, bonding, and social challenge as it develops

Attention Deficit Hyperactivity Disorder

  • Attention deficit hyperactivity disorder (ADHD): Characterized by excessively inattentive, hyperactive, or impulsive behaviors
    • described 100+ years ago
  • Children with ADHD are more likely to have problems in
    • school
    • graduating high school
    • maintaining a job
    • abusing drugs
    • having healthy relationships
  • Symptoms appear by mid-childhood and last for 6+ months
  • ADHD impairs normal function to a significant degree in different settings:
    • Children: among friends, at school and home
    • Adults: at work and home
  • Diagnosis needs a comprehensive evaluation:
    • Clinical interview, parent & teacher ratings in children
    • self ratings in adults
  • Problems with attention may also be triggered by other conditions
  • ADHD has a strong genetic influence
    • Genes for dopamine and norepinephrine transmission may be affected
  • Altered activity is present in
    • Cerebral cortex
    • Delay in cortical development
    • Striatum- a part of the midbrain
    • Cerebellum (especially the right hemisphere)
  • Symptoms often change as growing older
    • Less hyperactivity
  • There is reduced catecholamine transmission in some individuals with ADHD
    • Prefrontal circuits need an optimal level of catecholamine stimulation
    • Reduced transmission could lead to weakened prefrontal cortex regulation of attention and behavior (symptoms of ADHD)
  • Treated with parent education, school-based intervention
    • Medications: stimulants (methylphenidate) and non-stimulant drugs
    • Meds all act by enhancing catecholamine stimulation
  • There is no cure to ADHD

Down Syndrome (DS)

  • Occurs at the time of conception (when egg is fertilized)
  • Down syndrome: caused by an extra copy of chromosome 21
    • Usually present in the egg but can also sometimes be in the sperm
  • Not linked to environmental or behavioral factors before or during pregnancy
    • The risk for down syndrome increases as the mother gets older
    • If the mother is 25 years of age, the risk is 1 in 1250
    • If the mother is 40 years of age, the risk is 1 in 100
  • Down syndrome can be diagnosed by prenatal screening tests
    • They accurately detect DS in around 70% of babies
    • Prenatal diagnoses can be obtained with either chorionic villus sampling or amniocentesis
    • Chorionic villus sampling (CVS): obtaining a sample of the chorionic villi in the placenta to get the fetus’s DNA
      • CVS can be done in 2 forms:
      • transcervical- through the cervix
        • miscarriage rates slightly higher if done this way
        • performed by inserting a thin plastic tube through the vagina and cervix to reach the placenta
      • transabdominal- through the belly
    • Amniocentesis: a prenatal test in which a small amount of amniotic fluid is removed from the sac surrounding the fetus for testing
      • The sample of amniotic fluid is removed through a fine needle inserted into the uterus through the abdomen, under ultrasound guidance.
      • Less than 1 ounce is collected
  • DS is associated with around 50 physical/developmental characteristics
  • Individuals with DS are likely to possess:
    • Mild to moderate intellectual disabilities
    • Low muscle tone
    • Upward slant of the eyes
    • Flat facial profile
    • Enlarged tongue
    • Increased risk of congenital heart defects
    • Respiratory problems
    • Digestive tract obstruction
  • Individuals with down syndrome show neurological changes similar to Alzheimer’s by 40 years of age
    • Experience cognitive decline by 60 years of age
  • DS babies develop as much as typical children but at a slower rate
  • There is currently no cure for DS

Dyslexia

  • Around 8-10 % of children in the US have a form of learning disability involving difficulties in the acquisition and use of listening, speaking, reading, writing reasoning, and mathematical abilities
  • Dyslexia: unexpected difficulty in speaking & reading in children & adults who otherwise possess the intelligence, motivation, and schooling necessary for accurate fluent reading
    • Dyslexia affected 80% of learning disabled
    • 15-20% of Americans
    • It is a persistent, chronic condition though improvements can occur
    • Most forms reflect a deficit in the language system
    • specifically in a component called phonology
    • Dyslexia results in difficulty in oral language and reading
    • Mispronunciations of words
    • lack of fluency in speech
    • hesitations before responding
    • word retrieval difficulties
  • One manifestation of dyslexia is a slow reading rate
    • An individual may learn to read words accurately but their reading is not fluent or automatic
    • This may be the only manifestation of dyslexia in languages that are consistent in the relationship between letters and sounds
  • Sometimes dyslexic adolescents or young adults are assumed to have “outgrown” dyslexia
    • This is due to their accurate albeit slow reading of words
  • The differences between dyslexic and non-dyslexic readers involve 3 important left hemisphere neural systems:
    • Parieto-temporal system
    • Occipito-temporal system
    • Broca’s area (left inferior frontal region)
  • Dyslexic readers have functional inefficiency in an extensive neural system in the posterior portion of the brain
    • This was determined from brain images from studies called “neural signature of dyslexia”
  • Dyslexia tends to run in families
    • GWAS (Genome wide association studies) in dyslexia have identified genetic variants that only account for <1% of risk
  • Dyslexia is conceptualized within a model that is dependent on many factors (genetic and environmental)
  • Treatments are focused on teaching the child that words can be broken up into smaller units of sound and that the sounds are linked with specific letter patterns
    • Requires practice in reading stories