ADHD Flashcards
What is the clinical phenotype of ADHD?
Inattention, hyperactivity, and impulsivity
What are ADHD types?
Predominantly inattentive
Predominantly hyperactive/impulsive
Combined
What are diagnostic criteria?
For children: 6 or more symptoms in one domain
For adolescents/adults >17: 5 or more symptoms
Impairment in academic/social/occupational functioning
What is boys to girls ratio?
2:1
Girls more likely to have ADHD-I
Does incidence vary as a function of age?
Yes,incidence rate in 10-17 y.o is almost twice as high compared to 5-9 y.o.
Which subtype has the highest prevalence rate?
ADHD-I
What cognitive construct is ADHD-I associated with?
Sluggish cognitive tempo
Which subtype has questionable validity?
ADHD-H
Which brain structures/pathways have been associated with ADHD?
Frontal regions
Reduced total brain volume, delayed cortical maturation in frontal/temporal regions, abnormalities in CC, prefrontal, temporal, and parietal cortex, and BG (most consistent)
What are functional imaging findings in ADHD?
Underactivation in frontocortical nad frontosubcortical networks
Decreased activation in dosrolateral prefrontal and dorsal anterior cingulate cortex
Deficits in network including frontal cortex and striatal-thalamic-cerebellar connections
What is heritability of ADHD?
30-35% first degree relatives
Relative risk 6-8 times that of general population
Genetic influences account for up to 75% of variance
What are candidate genes?
Multiple genes, cumulative effect accounts for a small %
Dopamine transporter DAT1
Genes affective dopamine and serotonin pathways
What are risk factors of ADHD?
Prematurity Birth complications Maternal smoking Lead exposure/toxicity Moderate to severe TBI
ADHD Comorbidities
ADHD w/o comorbid disorder is exception rather than rule
OCD, Tourette, dyslexia, ODD, CD, depression, anxiety
ADHD symptoms common in thyroid dysfunction, bipolar disorder, ADS, Klinefelter syndrome, neurofibromatosis, epilepsy, sleep disorder, and lead toxicity
Inattentive symptoms - internalizing disorders (depression)
H/I - externalizing (ODD, CD)
What are some shared etiological influences?
Chromosome 6p
Processing speed deficits - overlap between ADHD and dyslexia
How is ADHD diagnosed?
Clinical/behavioral diagnosis, rating scales
Utility of NP debated, insufficient Sn, SP, PPP, and NPP
What are NP findings in ADHD?
IQ - 1/2 SD below mean
Attention - higher rates of omission, commission errors, slower response time, and increased RT variability on CPT
Language - basic skills preserved, weaker performance on task requiring working memory (sentence repetition, processing lengthy instructions, writing organization)
VS - average, some weaknesses in the context of organisation demands
Memory - deficits in reliable encoding due to attention demands
EF - variable, small to moderate effect sized on set-shifting and interference control task
Sensorimotor - deficient fine motor skills in a subgroup
Engagement - important to consider possible incentives
What are findings of MTA study?
Medication treatment most effective
Addition of behavioral therapy no added benefit
Combined treatment larger effect than behavioral alone
What are non-stimulant ADHD meds?
Strattera (atomoxetine) - NE reuptake inhibitor
Improves tics, effective for comorbid anxiety
Guanfacine and clonidine - alpha adrenergic receptor agonists
What is assortative mating?
Nonrandom mating pattern in which individuals with similar genotypes and phenotypes mare more frequently than expected under random mating, potential explanation for increased comorbidity between two disorders
Pleiotropy
Situation in which one gene influences multple phenotypic traits
Gene locus on chromosome 6p affects both inattentive symptoms and dyslexia
What is comorbidity rate between ADHD and dyslexia?
25-40%
What are side effects of stimulants?
Insomnia, weight loss/anorexia
