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