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ADHD (Neurobiology (remitters vs. persisters (higher level functions:…
ADHD
Neurobiology
increased slow wave electroencephalograms
reduced total brain volume on MRI: dlPFC, striatum, cerebellum
possibly a delay in posterior to anterior cortical maturation
fronto-striatal dysfunction
increased dopamine transporter density in striatum
smaller volumes of caudate, corpus callosum, cerebellum, right frontal areas
increased cortical thinning
PET: abnormal cerebral glucose metabolism in frontal lobe
remitters vs. persisters
higher level functions: remitters show normalization
lower level functions: no difference between persisters and remitters
weaker functional connectivity --> top down impairment of control
Dopamine & Norepinephrine shortage
brain develops slower but no abnormal pattern
Go/NoGo task: less activation in ACC, PFC, striatum (normal if use medication)
Diagnostic Criteria DSM V
Inattention
eg. easily distracted by extraneous stimuli (for adults: unrelated thoughts)
Hyperactivity/Impulsivity
eg. leaves seat in situations where it is inappropriate (for adults: feeling restless)
6 or more of the symptoms in inattention and hyperactivity/impulsivity that have persisted for at least 6 months
symptoms directly negatively impact social, academic, occupational activities
for older adolescents and adults (17 years and older) at least 5 symptoms are required
several symptoms were present prior to age 12 years
several symptoms are present in two or more settings: home, school, work etc.
symptoms don't occur exclusively during the course of schizophrenia or another psychotic disorder
3 Types:
Combined
Predominantly inattentive (females exhibit it more often)
Prdominantly hyperactive/impulsive
specify if in partial remission: full criteria where previously met, fewer than full criteria have been met for the past 6 months, symptoms still result in impairment of functioning
specify current severity: mild to severe
Associated Features supporting diagnosis
mild delays in language, motor, social development
low frustration tolerance, irritability
increased risk of suicide attempt by early adolescence
Adult ADHD
symptoms of motor hyperactivity less obvious: rather restlessness, inattention, poor planning, impulsivity
often misdiagnosed and prevented from receiving effective treatments
Childhood predictors: combined subtype, symptom severity, presence of comorbid depression, high rates of other comorbidities, social adversity, parental psychopathology
ca. 20% of parents of children with ADHD will have ADHD themselves
stigma
fear about treating a "non-existent disease" or causing drug addiction with stimulant medication
stereotyped as lazy, bad, aggressive, underachievers
mistaking ADHD for mood or personality disorders
unhealthy lifestyle: smoking, alcohol, drug abuse, risky sexual behavior, inappropriate healthcare etc.
Criminality: more often arrested, convicted
Comorbidity is the rule: 75% has at least one other disorder
Proper diagnosis?
self-reported symptoms but be aware of underreporting & recall bias
diagnostic interview: questioning about childhood & current behavioral symptoms
comparison with parent & partner reports
increasing role of inattention and executive function difficulties
symptoms should be judged with reference to developmentally appropriate norms
use a broader onset criterion
diagnosis based on a systematic assessment of lifetime history of symptoms & impairment, not only based on first impression of th eclinician
use full medical history of psychiatric & somatic treatments & family history of similar issues
Neuropsychological Tests add complementary info about cognitive functions
1/3 will outgrow ADHD
1:1 ratio males: females
Functional Consequences
reduced school performance, academic attainment
social rejection
higher probability of unemployment
elevated interpersonal conflict, also family interactions
more likely to develop conduct disorder in adolescence & antisocial personality disorder in adulthood
likelihood of obesity
more likely to be injured eg. traffic accidents, violations in drivers
teenage pregnancy
quality of life impaired (based on self-reports)
Development & Course
difficult to talk about normative behaviors before age 4 (don't diagnose before age 6)
some parents first observe excessive motor activity during toddlerhood
most often identified during elementary school
Preschool
behavioral disturbances
Hyperactivity/ Impulsivity high, Inattention low, low recognized comorbidity
School Age
Inattention high, Hyperactivity/Impulsivity less prominent, low comorbidity
Adolescence
difficulty with social interactions, legal issues eg. smoking, injury, academic problems
Inattention high, Hyperactivity lower than Impulsivity, rising comorbidity
College Age
academic failure, occupational difficulties, self-esteem issues, substance abuse, injury/accidents
same levels of inattention, hyperactivity, impulsivity as in adolescence, but rising comorbidity
Adulthood
occupational failure, self-esteem issues, relationship problems, injury/accidents, substance abuse
Inattention highest, impulsivity high, hyperactivity in the low sub threshold range
Treatment
Psychoeducation: What is ADHD, what to expect, how to help, specialized parenting classes
Medication
1st choice: stimulant (stimulates release of dopamine)
Methylphenidate (Ritalin)
side effects: eating behavior, sleep, growth, lack of studies on long-term effects
effectiveness: just control of symptoms, not a cure
70% experiences positive improvements
focus on behavioral symptoms but less is known about social wellbeing
improvement of reading performance because ADHD is often comorbid with dyslexia
CBT
if parents don't want medication
more often for adults because of more secondary issues
smaller effects than for Ritalin
effects don't hold over longterm
Combination of therapy and medication : depends on comorbidity and subtype
Other: Dietary interventions (restrictive elimination, even no fruits), Cognitive trainings (computer programs)
unclear effects, methodological limitations
Models
Simple Deficit Models
Cognitive
Attentional Network Model
Tests: TEA-CH for sustained attention, Attentional network test, Continuous performance test
orienting/selective attention: focus attention on 1 stimulus in presence of distracting stimuli
executive control attention: control mental processes, flexibility, dividing attention, shifting
alerting/sustaining attention: continuous performance for a long period of time
Inhibition Model (Barkley)
Working memory impaired eg. manipulating or acting on events, initiation of complex behavior sequences
internalization of speech impaired
Luria Language Assessment for Complex Language
self-regulation of affect/motivation/arousal
core deficit: response inhibition
issue: How specific are those deficits for ADHD?
mediating role of inhibitory-based executive deficits
Motivational
Delay Aversion Model
trouble waiting, unable to stop reactions
Brain level: Meso limbic
Marshmallow Experiment
disrupted signaling of delayed reward
Multiple Developmental Pathways
Dual Pathways
Triple Pathways
Heterogeneity of ADHD
Cognitive & Motivational with different neural substrates
measures from different domains are best
traditonally: simple causal models of single, core dysfunctions
Risk & Prognostic Factors
Temperamental: reduced behavioral inhibition, effortful control, negative emotionality, elevated novelty seeking --> may predispose to ADHD but not specific to the disorder
Environmental: low birth weight, smoking during pregnancy, history of child abuse, neurotoxin exposure eg. lead, infections, alcohol exposure in utero --> correlation but not causation
Genetic & Physiological: high heritability of 76%, specific genes are neither necessary nor sufficient causal factors, visual & hearing issues, metabolic abnormalities, sleep disorders, nutritional deficiencies, epilepsy, motor delays
Course modifiers: family interaction patterns in early childhood (unlikely to cause ADHD but can influence its course and lead to conduct problems)
Comorbidity
Oppositional Defiant Disorder in ca. half of the children with combined type
Conduct disorder in 1/4 of children with combined type
specific learning disorder
Anxiety, Major Depression, OCD, Autism
Differential Diagnosis
Oppositional Defiant Behavior
resist conforming to others' demands, hostility, negativity
Intermittent Explosive Disorder
high impulsivity, serious aggression towards others, no attention issues
Stereotypic Movement Disorder
Prevalence: 5% in children and 2.5% in adults
more frequent in males (2:1)