ADHD Etiology and Development

ADHD Overview

Course: PSYC 337 - Child Psychological Disorders

Developmental Course

• Symptom Presentation:
  • Hyperactivity/Impulsivity:
  • Typically decreases with age
  • Inattention:
  • Tends to persist into adulthood
• Stability:
  • ADHD symptoms show stability in ~80% of cases
  • Majority (65%) of individuals do not meet diagnostic criteria as adults

Etiology of ADHD

• Factors Ruled Out:
  • Diet
  • Family environment
• Causal Agents:
  • Multiple agents have been identified, but none have been confirmed as completely definitive or exclusive

Genetic Basis

• Twin Studies:
  • Monozygotic (MZ) twins: ~80% concordance
  • Dizygotic (DZ) twins: ~33% concordance
• Family Studies:
  • Show genetic link through top-down, bottom-up, and lateral approaches
• Specific Genes:
  • Yet to be clearly identified; possibly related to the DAT1 gene

Neurobiology

• Dopamine Receptors:
  • Critical brain regions affected include:
  • Prefrontal Cortex:
    • Responsible for attention
  • Basal Ganglia:
    • Responsible for inhibiting behavior
  • Limbic System:
    • Responsible for regulating emotions
• Developmental Lag:
  • Children with ADHD may lag behind non-ADHD peers by approximately 3 years in development

Early Environmental Factors

• Prenatal Influences:
  • Exposure to cigarette smoke
• Perinatal Influences:
  • Factors such as premature birth, low birth weight (LBW), and anoxia during delivery
• Postnatal Influences:
  • Conditions like sleep apnea
• Impact on Brain Development:
  • Anoxia is particularly detrimental to the developing prefrontal cortex