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47 Cards in this Set
- Front
- Back
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What are the three subtypes of ADHD?
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1. Inattentive
2. Hyperactive/impulsive 3. Combined |
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What are 2 controversies surrounding ADHD?
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1. Difficulty defining core symptoms
2. Concerns about overdiagnosis |
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What is the most common referral for ADHD?
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Pediatric physicians (50%)
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What is the estimated prevalence for ADHD?
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3-16%
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What percentage of ADHD referrals are made by teachers?
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46.4%
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What percentage of ADHD referrals are made by parents?
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30.2%
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What percentage of ADHD referrals are made by primary care physicians?
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11.3%
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What is Criterion A of the Categorical Approach?
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Frequency (6 of 9) and severity of symptoms
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What is Criterion B of the Categorical Approach?
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Onset (<7 yr old) and duration (>6mo) of symptoms
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What is Criterion C of the Categorical Approach?
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Symptoms must be present in two or more settings
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What are three criticisms of Criterion A?
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1. Symptoms present in continuum rather than categorical dichotomy
2. Some behaviours not necessarily symptoms (behavioural trajectory) 3. Criteria too conservative for adolescents and adults |
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What are two criticisms of Criterion B?
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1. Difficulty collecting accurate info (ie inattentive type symptoms more covert in early years)
2. 6 month period too short |
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What are three criticisms of Criterion C?
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1. Setting variability makes it difficult to reliably examine this criterion
2. Behaviour can become worse under certain circumstances 3. Omnipresence of comorbidities |
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When is ADHD behaviour worse?
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1. Later in day
2. Under greater task complexity 3. If restraint demanded 4. Under low levels of stimulation 5. Variable schedules of immediate consequences 6. Longer delay periods prior to reinforcement 7. In the absence of adult supervision |
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What are some identified biases of ADHD?
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1. Gender (From 4:1 to 2:1 Boys:Girls)
2. False positive 3. Developmental |
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How are the volumes of white and grey matter affected in ADHD? Specifically what area of the brain?
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They are smaller, especially in the PFC
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Where is grey matter suspected to be increased in ADHD?
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Posterial parietal areas
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How is cerebral volume affected in ADHD?
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It is smaller
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Which brain structures are smaller in ADHD?
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Corpus callosum, left caudate and head of caudate nucleus, ACC, cerebellum
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What is noted for cortical maturation in ADHD?
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It is delayed; 50% of peak thickness at age 10.5 (ADHD) vs 7.5 (controls)
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What are three neurophysiological correlates of ADHD?
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1. Disfunction of fronto-striatal circuits
2. Cathecolamines (DA & NE) 3. Sensitivity to saliency of reward demonstrated by dopaminergic burst in fronto-striatal circuit (impulsivity) |
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Definition
Ecological validity |
Results should inform us about intervention needs
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Why is dimensional better than disorder?
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1. Dimensional considers quantitative variation through distribution instead of qualitative diagnosis
2. Considers continuous traits ND instead of extreme differences 3. Studies based on larger unselected samples |
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Definition
Endophenotypes |
Heritable, quantitative traits that index an individuals liability to develop or manifest a given disease
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What are some potential candidtates for endophenotypes of ADHD?
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Verbal and visual spatial WM, response variability, brain imaging, multidimensional behavioural data
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Definition
Lissencephaly |
Failure to develop gyri and sulci
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Definition
Polymicrogyria |
Excessive folding
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When does synaptogenesis occur?
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From second trimester to adulthood
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How does myelination occur throughout the brain?
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From posterior to anterior regions; from primary to tertiary cortex
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Definition
Pruning |
Strengthening of synaptic connections and loss of large number of neurons
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How many neurons are lost through pruning during childhood?
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~40%
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What are the phases of synaptic formation?
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1. Phases 1&2: low density synaptogenesis
2. Phase 3: increased synaptogenesis (experience expectant and dependent mechanisms 3. Phase 4: initial plateau followed by pruning 4. Second plateau followed by slow steady decrease in density |
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At what ages does neurulation occur?
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Within the first trimester
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At what ages does cell proliferation and migration occur?
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Primarily over the second trimester
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At what ages does peak myelination of the sensorimotor cortex occur?
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Birth to 2 months
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At what ages does peak myelination of the parietal and temporal association cortices occur?
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Around 8 months
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At what ages does peak myelination of the prefrontal cortex occur?
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Around 1-6 years
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Is there a gender bias for frontal lobe grey matter development? If so, which?
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Yes, females develop more
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Definition
Teratogen |
An agent that may disrupt the development of the embryo or fetus
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What are some teratogens?
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Drugs, diseases, STDs, toxins, radiation
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Definition
Agenesis |
Failure of an organ to develop during embryonic growth and development.
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Definition
Dysgenesis |
Abnormal organ development during embryonic growth and development.
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Definition
Micrencephaly |
Abnormal smallness of the brain.
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Definition
Megalencephaly |
Abnormal largeness of the brain.
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Definition
Agenesis of the corpus callosum |
Complete or partial absence of the corpus callosum.
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Definition
Agyria |
No gyri
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Definition
Focal dysplasia |
A congenital abnormality where the neurons in an area of the brain failed to migrate in the proper formation in utero; source of seizures, especially intractable epilepsy.
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