Developmental Delays in Children

Global Developmental Delay (GDD)

• GDD is often considered a "placeholder" diagnosis for children too young to be diagnosed with Intellectual Disability (ID)
• Not all children with GDD have concurrent deficits in intellectual functioning; many earn scores within the average range
• Identification:
  • 1-3% of infants and toddlers have GDD
  • Physical exams and blood tests can help identify genetic disorders
  • Chromosomal microarray (CMA) identifies copy number variants in major regions of the genome
  • Most common genetic disorders causing GDD are Down syndrome, Fragile X syndrome, Rett syndrome, and subtle translocations or deletions of portions of the genome
  • About 4% of children with GDD have an identifiable genetic disorder that explains their delays

Challenging Behaviors in Children with Developmental Disabilities

• About 25% of youths with ID engage in challenging behaviors
• Challenging behaviors can be physically harmful, strain relationships, limit access to normal childhood experiences, interfere with learning and cognitive development, and place a financial burden on the family and the public
• Types of challenging behaviors:
  • Stereotypies: repetitive behaviors with no immediate practical significance
    • Examples: repeated movements of hands, arms, or upper body; facial grimacing, face and head tapping, self-biting, and licking
    • Especially common in youths with ID and autism
  • Self-Injurious Behaviors (SIBs): repetitive movements that cause physical harm or damage
    • Examples: head banging, self-biting/scratching
    • 10-12% of children with IDs engage in SIBs, prevalence is directly related to intellectual and adaptive impairments
  • Physical Aggression: behavior that causes property destruction or harm to another person
    • Examples: throwing objects, breaking toys, hitting, kicking, and biting others
    • 20-25% of youths with ID show chronic problems with aggression, most common among boys, children with comorbid autism, and youths with poor communication skills

Prenatal and Perinatal Problems Associated with Intellectual Disability

• Maternal infections during pregnancy:
  • Cytomegalovirus (CMV): can cause damage to the fetus's CNS, hearing loss, ID, and death
  • Herpes 2 (HSV-2): can cause damage to the CNS, blindness, seizures, and ID
  • Zika virus: can cause severe damage to the developing CNS, microcephaly, cognitive impairment, and death
• Lead exposure:
  • Lead is a neurotoxin that can cause developmental disabilities in children
  • Fetuses are at risk if mother is exposed to lead during gestation
  • Lead exposure can cause kidney damage, heart problems, and other metabolic issues
• Alcohol and other drugs:
  • Fetal Alcohol Spectrum Disorder (FASD): associated with low intellectual functioning, learning disabilities, hyperactivity, slow physical growth, craniofacial anomalies, and cardiac problems
  • Prevalence of FASD: approximately 1-3 per 1,000 live births
  • Can occur from only 2-3 oz of alcohol per day of gestation

Perinatal and Postnatal Problems Associated with Intellectual Disability

• Complications with pregnancy and delivery:
  • Maternal hypertension or uncontrolled diabetes
  • Delivery complications that cause anoxia leading to CNS damage
• Premature birth and/or low birth weight:
  • One of the greatest predictors of cognitive problems in children

Quiz on developmental delays in children, including GDD, ID, cerebral palsy, and impact of social deprivation and economic hardship.