Review Session Thursday December 15 th 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)

Symptoms InattentionHyperactivity/Impulsivity Fails to give close attention to detailsFidgets with hands or feet or squirms Has difficulty sustaining attentionCan’t remain seated when required Does not seem to listenRuns about when inappropriate Does not follow throughHas difficulty keeping quiet Has difficulty organizing tasksIs always on the go or “driven by a motor” Avoids tasks requiring sustained effortTalks excessively Loses thingsBlurts out answers Is distracted by extraneous stimuliHas difficulty waiting turn Is forgetfulInterrupts or intrudes Symptoms need to be persistent for over 6 months and be maladaptive or inconsistent for developmental age

Quality of Life ADHD associated with: Low academic achievement School suspensions Poor peer-family relations Anxiety and depression Aggression Conduct problems Substance experimentation and abuse Accidents (especially driving) Difficulties in adult social relationships Problems in marriage Difficulty keeping employment

Subtypes Predominantly 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 although inattention may still be present to some degree. Symptoms of inattention and hyperactivity-impulsivity Most prevalent subtype

Time Mullins et al Time reproduction task -judge/replicate time intervals -Controls, ADHD Inattentive, ADHD Combined (Children) Controls preformed significantly better than both ADHD groups at long intervals No sub-type differences in time reproduction Time reproduction thought to be a measure of sustained attention

Motivation Stop Signal Task under conditions of low or high incentive Normal Control Group, ADHD group, Clinical Control Group (Children) Slusarek et al 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 ADHD should be regarded in a way that separates performance from 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 Counting Stroop Task Un-medicated ADHD adults and Controls Hypothesis: ACC dysfunction might lead to inattention/impulsivity symptoms observed in ADHD ADHD: deficits in interference inhibition

Interference Results: -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 DA pathways may contribute ADHD pathophysiology DA dysfunction particularly in the striatum and PFC in ADHD

Pharmacological Treatments Medications for ADHD enhance catecholamine (NE &/or/both DA) transmission by 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 most but their neural effects not fully characterized

Medication Sustained 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 response Omission Error: failed to make a correct response (Johnson et al. 2008)

Medication Rubia et al 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 TrialIncongruent Trial + + Press Left

Medication Results: 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!