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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