ADHD

Question 1

Diagnostic criteria

Answer 1

• 6+ symptoms of inattention (distractable)
• 6+ symptoms of hyperactivity - impulsivity (restless, fidgety, interrupts)
• to a degree that is inconsistent with developmental level
• negatively impacts social/academic/occupational activities
  *

Question 2

Genetics

Answer 2

• fairly high heritability (similar to schizophrenia, 2nd to autism)
• implicated genes are **receptors or transporters **involved in dopamine and norepi pathways (possible role for serotonin)

Question 3

Affected neurotransmitter pathways

Answer 3

• recycling of dopamine may be defective
• receptors may be less efficient or under-expressed at binding dopamine
• norepi pathways defective (norepi needed to maintain attention, along w/ dopamine)

Question 4

Genes and smoking + other risk factors

Answer 4

• certain alleles involved in dopamine transport and receptor were more associated with developing ADHD when the mother smoked during pregnancy
• Other risk factors:
  
  • neglect/deprivation, family adversity, toxin exposure (etoh, Pb), encephalopathy

Question 5

Neuroanatomy of ADHD: regions and changes in the brain

Answer 5

• Orbital prefrontal cortex (PFC)– working memory, exec functions
  
  • ** PFC helps with top-down regulation, ADHD brain is not good at this
• Basal ganglia (motor coordination, procedural knowledge) & Cerebellum – movement control
• 3-10% reduction in regional volumes in ADHD pts
  
  • reach typical brain volumes by teens (delayed development & cortical maturation)
• connectivity b/t PFC and basal ganglia/cerebellum = disregulated
• underactivity in anterior cingulate

Question 6

Functional circuits of ADHD pathophys

Answer 6

• front-cerebellar (timing/efficiency)
• reward (decreased normal reward response)
• fronto-striatal (guiding behavior)
• executive function
• attentional

Question 7

Treatment

Answer 7

• Methylphenidate:
  
  • activates anterior cingulate, slows dopamine re-uptake, increases norepi and dopamine activity in prefrontal cortex
• Amphetamines:
  
  • increase production/release of dopamine
  • blocks uptake into vesicles, diffuses into vesicles causing DA to be released into the cytoplasm, blocks MAO,
  • sub-types act on either DA or NE neurons
• Strattera:
  
  • decreases norepi re-uptake
• multi-modal/combined therapies –> therapy, meds, education, accomodations, training
• meds can include SSRI’s, mood stabilizers as adjuncts