review session thursday december 15 th at 3:00pm th 173
DESCRIPTION
Review Session Thursday December 15 th at 3:00pm TH 173. Attention Deficit Hyperactivity Disorder (ADHD). Background. Attention Deficit Hyperactivity Disorder (ADHD) -developmental disorder -3-7% of childhood population -2-5% of adult population -heritability 80%. Hallmark Symptoms - PowerPoint PPT PresentationTRANSCRIPT
Review Session Thursday December 15th at 3:00pm
TH 173
Attention Deficit Hyperactivity Disorder (ADHD)
Background
Hallmark Symptoms- inattention, impulsivity & hyperactivity
Attention Deficit Hyperactivity Disorder (ADHD)-developmental disorder -3-7% of childhood population-2-5% of adult population-heritability 80%
ADHD previously known as:- Hyperactive Child Syndrome- Hyperkinetic Reaction of Childhood- Minimal Brain Dysfunction- Attention Deficit Disorder (with or without hyperactivity)
SymptomsInattention Hyperactivity/ImpulsivityFails to give close attention to details Fidgets with hands or feet or squirms
Has difficulty sustaining attention Can’t remain seated when required
Does not seem to listen Runs about when inappropriate
Does not follow through Has difficulty keeping quiet
Has difficulty organizing tasks Is always on the go or “driven by a motor”
Avoids tasks requiring sustained effort Talks excessively
Loses things Blurts out answers
Is distracted by extraneous stimuli Has difficulty waiting turn
Is forgetful Interrupts or intrudes
Symptoms need to be persistent for over 6 months and be maladaptive orinconsistent for developmental age
Quality of Life
ADHD associated with:
Low academic achievementSchool suspensionsPoor peer-family relationsAnxiety and depressionAggressionConduct problemsSubstance experimentation and abuseAccidents (especially driving)Difficulties in adult social relationshipsProblems in marriageDifficulty keeping employment
SubtypesPredominantly Inattentive
Predominantly Hyperactive-Impulsive
Combined Hyperactive-Impulsive and Inattentive
The majority of symptoms are inattentive although hyperactivity-impulsivity may still be present to some degree.
The majority of symptoms are hyperactive-impulsive althoughinattention may still be present to some degree.
Symptoms of inattention and hyperactivity-impulsivityMost prevalent subtype
TimeMullins et al. 2005 Time reproduction task-judge/replicate time intervals-Controls, ADHD Inattentive, ADHD Combined (Children)
Controls preformed significantly better thanboth ADHD groups at long intervals
No sub-type differencesin time reproduction
Time reproduction thought to be a measure of sustained attention
Motivation
Stop Signal Task under conditions of low or high incentiveNormal Control Group, ADHD group, Clinical Control Group (Children)
Slusarek et al. 2001
Low incentive: ADHD group less likely to inhibit reaction and longer SSRT
High Incentive: ADHD group preformed the task just as well as the other groups
Inhibition deficits in ADHDshould be regarded in a way that separates performancefrom ability.
Motivational and reinforcement deficits in ADHD
Interference
Anterior Cingulate Cortex (ACC)-stimulus selection when faced with competing information-response selection (facilitate correct; inhibit incorrect)
Bush et al. 1999Counting Stroop TaskUn-medicated ADHD adults and Controls
Hypothesis: ACC dysfunction might lead to inattention/impulsivity symptomsobserved in ADHD
ADHD: deficits in interference inhibition
InterferenceResults:
-the ADHD group, unlike controls, failed to activate the ACC during interference trials-ADHD group using alternate networks
Conclusion:Possible dysfunction of the ACC in ADHD
Prefrontal Cortex (PFC)Functions:
-sustaining attention, inhibiting distraction, dividing attention, behavioural inhibition
Lesions:- cause distractibility, forgetfulness, impulsivity and hyperactivity
PFC is highly sensitive to its neurochemical environment
Genetic alterations to NE and DApathways may contribute ADHDpathophysiology
DA dysfunction particularly inthe striatum and PFC in ADHD
Pharmacological Treatments
Medications for ADHD enhance catecholamine (NE &/or/both DA) transmissionby enhancing the release or inhibiting the reuptake of NE and/or DA
Why NE & DA?-NE enhances signals-DA decreases “noise”
Examples:Methylphenidate (Ritalin)Amphetamine (Adderall)Dextroamphetamine (Dexedrine)
Medications are an effective treatment for mostbut their neural effects not fully characterized
MedicationSustained Attention to Response Task (SART)
-presented a sequence of numbers and were not to respond to the number 3-Tested before and after 6 weeks of treatment with MPH-ADHD children and Controls
Administration of MPH resulted in significantly less errors of commission but not of omission
Commission Error: made an incorrect responseOmission Error: failed to make a correct response
(Johnson et al. 2008)
MedicationRubia et al. 2011
Simon Task-measures interference inhibition and selective attention -wanted to investigate the effects of a single does of MPH-ADHD boys and controls on MPH or placebo-Compared incongruent to congruent trials
Congruent Trial Incongruent Trial
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Press Left Press Left
MedicationResults:
Significantly reduced activation in ADHD vs Controls in the placebo condition
In MPH condition, difference between groups no longer observed in frontal-striatal network
Conclusion: MPH significantly normalizes frontal-striatal underfunctioning in ADHD
The End
Happy Last Class Day!