2 brain function
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The document discusses brain structure and function in ADHD. It notes differences in maturation and abnormalities in the prefrontal cortex, basal ganglia, and cerebellum which are associated with executive functions like attention, memory, and inhibition. Executive functions allow planning, organization, problem solving, and self-monitoring. Deficits in these areas impact behavior. ADHD is characterized as a disability of executive function that affects attention, effort, impulse control, organization, and more. Genetics play a major role in ADHD development along with environment.
2 brain function
- 1. IEC 4020: ADHD Section Two Brain Function
- 2. Brain Structure & Function in ADHD • Differences in brain maturation, structure, function are seen in ADHD (particularly abnormalities in frontostriatal circuitry): • Prefrontal cortex • Basal ganglia • Cerebellum • These areas of the brain are associated with executive function abilities: • Attention, spatial working memory, and short-term memory • Response inhibition and set shifting
- 3. What Are Executive Functions? An executive function is: “A neuropsychological concept referring to the cognitive processes required to plan and direct activities, including task initiation and follow through, working memory, sustained attention, performance monitoring, inhibition of impulses, and goal-directed persistence.” (Dawson & Guare, 2004, p. vii)
- 4. Executive Function (EF) Normal functioning EF governs goal directed, flexible & intentional behaviours. These include: Goal setting (aiming for a particular cognitive or behavoural outcome) Planning & Organization of behaviours and thoughts Problem solving Holding information in mind (working memory) Shifting set (redirecting attention between tasks) Self-monitoring/checking
- 5. Why Are Executive Functions Important? These skills allow us to “organize our behavior over time and override immediate demands in favour of longer- term goals” (Dawson & Guare, 2004, p. 1). For example, we study hard now so that we can get a good paying job later. They also allow for the management of emotions and effective thought monitoring. For example, inhibit outburst when feeling angry or sad. Children with problems in a particular executive function area have a deficit in that skill area.
- 6. ADHD Brain Imaging: Frontal-Striatal dysfunction Normal Adult ADHD Adult normal activation reduce activation * ADHD adults fail to utilize the most efficient pathway to process information in an attention-based task. MGH-NIMR Center & Harvard – MIT CITP, Bush G, et al. Biol Psychiatry 1999.
- 7. Executive Function Developmental Perspective In typically developing child, EF develop as a function of brain growth/development. At least 20% of children with ADHD lag behind their peers in brain development, hence in EF development.
- 8. ADHD is a Disability of Executive Function ADHD impairs the ability to separate action and reward ADHD is a disability of the “To-Do” mechanism of the brain. • Not a disability of interest-based function • It is a disability of importance-based function Affects every action, every second Disrupts every life path
- 9. ADHD Affects All Executive Functions Impaired EF Observed Behavior Attention inattention, distractibility Sustained effort “not trying”, poor follow-through Modulation of impulse poor self-control, risk-taking Organization disorganized locker/backpack, schedule Social skills may not play well with others, loses friends Self-observation unaware of behavior, emotions, effectiveness, others Emotional self-control poor frustration tolerance, lack of empathy
- 10. Risks Increase for adults with ADHD Barkley, R. A., Murphy, K. R., & Fischer, M. (2008). ADHD in Adults: What the Science Says. New York: Guilford.
- 11. ADHD: Etiological Factors ADHD has a high genetic loading with heritability of .80 - .85. This means that genes play a major play in the development of ADHD. Environmental factors are not the cause, but may contribute to the expression, severity, course, and comorbid conditions (that is, having another condition) Dysfunction in prefrontal lobes resulting in problems with inhibition, and executive functions Kieling, Gondaves. Tannock. & Castellanos. 2008; Mick &. Faraone, 2008
- 12. Comparing genetic loadings of ADHD and other disorders/traits Height ADHD Schizophrenia IQ Depression 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Heritability Index Faraone SV. J Am Acad Child Adolesc Psychiatry 2000;39:1455-7.
- 13. ADHD: Etiological Factors Genes involved in dopamine regulation have been implicated in ADHD Dopamine transporter (DAT1) gene implicated 7 repeat of dopamine receptor gene (DRD4) implicated However, Gene x Environment interaction is deem to be the deciding factor in the development of ADHD Differences in size of brain structures seen in ADHD: Prefrontal cortex, Corpus callosum, caudate nucleus Kieling, Gondaves. Tannock. & Castellanos. 2008; Mick &. Faraone, 2008
- 14. Adults with ADHD ADHD is persistent across lifespan in most cases Methodological issues impact estimates of persistence, ADHD severity, psychiatric comorbidity. Parental psychopathology predict persistence (Biederman et al., 2011) Inattention remains stable; hyperactivity declines with age But DSM criteria may not capture adolescent/adult manifestations of impulsivity Adult outcomes including psychiatric comorbidity When ADHD co-occurs with conduct disorder, chronic criminality and serious substance use can result When ADHD co-occurs with depression, risk of suicide increased
- 15. ADHD: Issues across Lifetime 1) Peer problems Inattentive symptoms resulted in being ignored by others Hyperactive/impulsive symptoms resulted in being actively rejected by others These children are not deficient in social reasoning/ understanding, but rather they have difficulty in the execution of appropriate social behavior 2) Family dysfunction/parental issues No clear causal relationship between family problems and development of ADHD 3) Self-esteem Low self esteem associated with comorbid depression
- 16. Success decreases for adults with ADHD Barkley, R. A., Murphy, K. R., & Fischer, M. (2008). ADHD in Adults: What the Science Says. New York: Guilford.
- 17. Risks of ADHD Calculated effect of ADHD on life expectancy: 7 year decrease in adults with AD/HD* 3 year decrease in adults with heart disease. *Calculation (by R. Barkley) taking into account increased smoking, obesity, decreased medical compliance, exercise in adults with AD/HD.
- 18. “ADHD is not a problem with knowing what to do; it is a problem of doing what you know.” -Barkley, 2006 It is a performance deficit rather than a knowledge deficit
- 19. End of section two Your Task: Please complete the quiz before moving on to section three of the lecture.