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ADHD and Executive Functions: Emerging Concepts

ADHD and Executive Functions: Emerging Concepts. Thomas E. Brown, PhD Associate Director, Yale Clinic for Attention and Related Disorders Department of Psychiatry Yale Medical School. Shifts in Conceptualizing ADHD. 1968 Hyperkinetic Disorder of childhood 1980 Attention Deficit Disorder

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ADHD and Executive Functions: Emerging Concepts

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  1. ADHD and Executive Functions: Emerging Concepts Thomas E. Brown, PhD Associate Director,Yale Clinic for Attention and Related DisordersDepartment of Psychiatry Yale Medical School

  2. Shifts in Conceptualizing ADHD • 1968 Hyperkinetic Disorder of childhood • 1980 Attention Deficit Disorder • 1987 ADHD (only combined symptoms) • 1994 AD/HD–3 types • 2000 AD/HD (impaired executive function) • With or without hyperactivity • Residual type recognized

  3. Prevalence and Genetics of ADHD • 9% of children; 4.4% of adults • Male-female: 6:1, 3:1, 1:1 • All levels of IQ • All levels of socioeconomic status • Family genetic transmission: 7.5 – 8.0 • Inheritance not specific to subtype CDC 2008; Kessler, 2006; Gaub M, Carlson CL. J Am Acad Child Adolesc Psychiatry. 1997;36(8):1036-1045.Levy F, et al. J Am Acad Child Adolesc Psychiatry. 1997;36(6):737-744.Smalley SL, et al. J Am Acad Child Adolesc Psychiatry. 2000;39(9):1135-1143.

  4. 0 0.2 0.4 0.6 0.8 1 ADHD Genetics: Heritability Coefficient Asthma Schizophrenia Height Breast cancer Hudziak, 2000 Nadder, 1998 Levy, 1997 Sherman, 1997 Silberg, 1996 Gjone, 1996 Thapar, 1995 Schmitz, 1995 Edelbrock, 1992 Gillis, 1992 Goodman, 1989 Willerman, 1973 Average genetic contribution of ADHD based on twin studies ADHD Mean Faraone. J Am Acad Child Adolesc Psychiatry. 2000;39:1455-1457. Hemminki. Mutat Res. 2001;25:11-21.Palmer. Eur Resp J. 2001;17:696-702.

  5. What is ADHD?(A Controversial Viewpoint) ADHD (all subtypes) = Developmental Impairment of Executive Functions Developmental Impairment = (Not emerging and unfolding as expected for age) Attention Deficit Disorder: The Unfocused Mind in Children and Adults (T.E. Brown, Yale University Press, Sept, 2005)

  6. Executive Functions • Wide range of central control processes of the brain • Connect, prioritize, and integrate cognitive functions–moment by moment • Like conductor of a symphony orchestra

  7. “Focus” and Executive FunctionImpairments of ADHD • In DSM-IV “inattention” symptoms of ADHD • Do not mean • Unable to focus as in holding the camera still to take a photo of an unmoving object • Do mean • Unable to focus as in focusing on the task of driving a car Brown TE. In press.

  8. Brown’s Model of Executive Functions Impaired in ADHDSymptom Characteristics • Dimensional, not “all-or-nothing” • Everyone sometimes has some impairments in these functions; in ADHD, it is a chronic, severe impairment • Situational variability: “If I’m interested” • Most persons with ADHD have a few activities where ADHD impairments are absent ADHD looks like a willpower problem, but it isn’t!

  9. Organizing, prioritizing, and activatingto work Focusing, sustaining focus, and shifting focus to tasks Regulating alertness, sustaining effort, and processing speed Managing frustration and modulating emotions Utilizing working memory and accessing recall Monitoring and self-regulating action 1. Activation 2. Focus 3. Effort 4. Emotion 5. Memory 6. Action Brown’s Model of Executive Functions Impaired in ADHD Executive Functions Brown TE. Manual for Attention Deficit Disorder Scales for Children and Adolescents; 2001.

  10. 1. Organize, Prioritize, and Activate • Difficulty organizing tasks, materials • Difficulty estimating time, prioritizing tasks • Trouble getting started on work Brown TE. Attention-Deficit Disorders and Comorbidities in Children, Adolescents, and Adults; 2000. Brown TE. Manual for Attention Deficit Disorder Scales for Children and Adolescents; 2001.

  11. 2. Focus, Shift, and Sustain Attention • Loses focus when trying to listenor plan • Easily distracted–internal/external • Forgets what was read, needsto re-read Brown TE. Attention-Deficit Disorders and Comorbidities in Children, Adolescents, and Adults; 2000. Brown TE. Manual for Attention Deficit Disorder Scales for Children and Adolescents; 2001.

  12. 3. Regulating Alertness, Effort,and Processing Speed • Difficulty regulating sleep and alertness • Quickly loses interest in task, especially longer projects; doesn’t sustain effort • Difficult to complete task on time, especially in writing–“slow modem” Brown TE. Attention-Deficit Disorders and Comorbidities in Children, Adolescents, and Adults; 2000. Brown TE. Manual for Attention Deficit Disorder Scales for Children and Adolescents; 2001.

  13. 4. Manage Frustration,Modulate Emotion (Not included in DSM-IV criteria) • Emotions impact thoughts, actions too much • Frustration, irritations, hurts, desires, worries, etc., experienced “like computer virus” • “Can’t put it to the back of my mind” Brown TE. Attention-Deficit Disorders and Comorbidities in Children, Adolescents, and Adults; 2000. Brown TE. Manual for Attention Deficit Disorder Scales for Children and Adolescents; 2001.

  14. 5. Utilize Working Memory,Access Recall • Difficulty holding one or several things “on line” while attendingto other tasks • Difficulty “remembering to remember” • Inadequate “search engine” for activating stored memories, integrating these with current info to guide current thoughts and actions Brown TE. Attention-Deficit Disorders and Comorbidities in Children, Adolescents, and Adults; 2000. Brown TE. Manual for Attention Deficit Disorder Scales for Children and Adolescents; 2001.

  15. 6. Monitor and Self-Regulate Action (Not just hyperactive/impulsive behavior) • Difficulty controlling actions, slowing self and/or speeding up as neededfor tasks • Doesn’t size up ongoing situations carefully • Hard to monitor and modify own actions to fit situation/aims Brown TE. Attention-Deficit Disorders and Comorbidities in Children, Adolescents, and Adults; 2000. Brown TE. Manual for Attention Deficit Disorder Scales for Children and Adolescents; 2001.

  16. What Requires Executive Functions? • Tasks that involve managing oneself • To prioritize, start, sustain, shift, stop, and integrate cognitive functions • Using memory without moment-by-moment guidance from others Brown TE. In press.

  17. Executive Functions:Development and Demands • EF capacity develops through childhood, into adolescence, and beyond; it is not fully present in early childhood • Environmental demands for EF increase with age, from preschool through adulthood • EF impairments often are not noticeableby age 7! Brown TE. Emerging understandings of attention deficit disorders and comorbidities. In: Brown TE, ed. Attention-Deficit Disorders and Comorbidities in Children, Adolescents, and Adults; 2000:3-55.

  18. Executive Functions and Scaffolding • In early childhood, others perform all executive functions for the child (parents, teachers, sibs and other caretakers) • Scaffolding is provided by showing, directing, helping, reminding, coaching, critiquing (Examples: walking, getting dressed, crossing street, riding bike, driving car) • Scaffolding is gradually withdrawn, as child becomes able to (or is forced to) perform these functions for self • In adolescence & adulthood scaffolding may be provided by: friends, teachers, coaches, spouses, supervisors

  19. How Can Executive FunctionsBecome Impaired? • Developmentally, eg, ADHD • Trauma, eg, traumatic brain injury • Disease, eg, Alzheimer’s disease • In trauma and disease, the patient usually has had adequate EF, then loses it • In ADHD, EF has not developed adequately

  20. When Are ADHDImpairments Noticeable? • Some are obvious very early andare noticeable in preschool years • Some are not noticeable untilmiddle elementary or junior high • Some are not apparent until child leaves home to go to college or later

  21. Challenges May Reveal Weaknesses Cardiac weaknesses may not be noticeable in EKG taken while lying quiet on a table, but may be very noticeable while playing basketball, shoveling snow EF weaknesses may not be noticeable until one’s self-management is challenged by increased demands of adult life

  22. Development of Brain Structures that Support Executive Functions • Structures and functions that support EF are not fully developed at birth • Neural networks underlying effortful control begin development at 2-4 years old, but don’t fully develop until one’s 20s • Development of EF capacities continues into early adulthood Rothbart MK, Posner MI. Mechanism and variation in the development of attentional networks.In: Nelson CA, Luciana M, eds. Handbook of Developmental Cognitive Neuroscience; 2001.

  23. Continuing Brain Development in Late Childhood and Adolescence • Between 6-15 years, extreme growth (to 80%) occurs at the collosal isthmus that supports associative relay, while considerable synaptic pruning occurs • Brain myelination increases 100% during the teenage years • Dopamine (DA), norepinephrine (NE), and serotonin (5-HT) transmitter systems in the brain continue to develop into one’s 20s Thompson PM, et al. Nature. 2000;404(6774):190-193. Benes FM, et al. Arch Gen Psychiatry. 1994;51(6):477-484.

  24. Cortex Maturation in ADHD vs NC • MRI studies of 40K cortex sites in 223 youths with ADHD vs matched controls • Brain maturation was delayed ~3yrs in specific regions in ADHD youths vs NC • Frontal areas of cortex slower in ADHD • Medial PFC developed lagged 5 yrs (Shaw, et al, PNAS, Nov, 2007)

  25. Emotion regulates EFs • “All information processing is emotional …emotion is the energy level that drives, organizes, amplifies & attenuates cognitive activity.” (K. Dodge, 1991) • Emotional value is automatically, uncsly assigned to stimuli (amygdala, medial PFC) [how threatening, important, interesting is this?] (Damasio, 1994, 1999; LeDpux, 1996, 2002,) • Brain imaging studies show reciprocal connections via medial PFC between emotion and cognition, anxiety/dysphoria & attention (Mayberg, et al, 1999; Simpson, et al, 2001)

  26. EFs regulate emotion Brain imaging of NC shows “gating” of emotion to reduce affective interference during more valued/complex cognitive tasks. (Pochon, Levy, et al, 2002) Many persons with ADHD self-report chronic impairment in their ability to modulate affective interference in daily life. This is consistent with their other EF impairments (Brown, 1996, 2001)

  27. How Can Executive FunctionImpairments of ADHD Be Assessed? • When ADHD was seen as just a disruptive behavior disorder in childhood, diagnosis was based on observing overt behavior • EF impairments of ADHD are largely cognitive, covert, and not easily observed • Performance of complex, everyday tasks may be a more sensitive diagnostic indicator of EF impairments

  28. Conflicting Modelsre: How to assess EF impairments • Neuropsych tests of EF: WCST, Stroop, Rey-Ost., Tower of Hanoi, etc. (Wilcutt, et al, 2005) 2. Clinical interviews re: past/present self-management of daily life (Barkley, 1997, Brown, 2005) (Brown, 2006)

  29. How Are EF Related to ADHD? 2 Conflicting Models • Partial overlap (~30%) EF impairments as characteristic of some individuals with ADHD, but not essential to the disorder (Willcutt, et al. 2005) • Full overlap (100%) -Combined subtype only (Barkley) - All subtypes(Brown) Brown TE. 2006.

  30. Some assume that Executive Functionsare defined by neuropsychological “tests of EF” • Single neuropsychological measures are not effective in identifying ADHD in children or adults • Multiple tests improved diagnosis efficiency (high positive predictive power, modest negative predictive power) • Multiple tests show about 30% of those with ADHD are impaired on EF Doyle AE, et al. J Consult Clin Psychol. 2000;68(3):477-488.

  31. Problems in Laboratory Measures of Executive Functions (“Streetlamp Problem”) • Most research tries to isolate, quantify, and measure effects of a single variable presumed to tax a single functional process • This strategy is inappropriate for EF “because an essential property of all “executive” behavior is that, by its nature, it involves simultaneous management of a variety of different functional processes”1 1. Rabbitt P. Methodologies and models in the study of executive functions and DSM-IV ADHD subtypes. In: Rabbitt P, ed. Methodology of Frontal and Executive Function; 1997.

  32. Elements of a New Paradigm for ADHD • ADD = developmental impairment of uncs self-management system of brain • Self-regulation of and by emotion is impaired in ADD • ADD sx may be noticeable in childhood, but often not apparent until challenges of adolescence/adulthood

  33. Elements of a New Paradigm for ADHD 4. ADD appears to be insufficient willpower, but is actually a problem of chemical dynamics in brain • Causes of ADD are primarily genetic, but environmental stressors & supports modify sx expression • ADD is a foundational disorder that increases lifetime risk of other disorders.

  34. My Website • To see more info • To download articles • To sign up for free email newsletter www.DrThomasEBrown.com ******************************************

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