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

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