390 likes | 509 Views
Early Brain and Child Development: Effects of Early Childhood Adversity and Toxic Stress, Resultant Language and Reading Delays. Eileen C. Vautravers, M.D. www.ne-da.org 402-434-6434.
E N D
Early Brain and Child Development:Effects of Early Childhood Adversity and Toxic Stress, Resultant Language and Reading Delays Eileen C. Vautravers, M.D. www.ne-da.org 402-434-6434
From Neurons to Neighborhoods: The Science of Early Childhood Development, 2000 (Nat. Acad. Press)Editors, Jack Shonkoff and Deborah Phillips • The Center on the Developing Child, Harvard University (www.developingchild.harvard.edu) • National Scientific Council on the Developing Child, Working Papers #1 through #12
Core Concepts in Early Brain and Child Development • Child development is foundation for community and economic development. • Brains are built over time. • Brains and developing abilities are built “bottom-up”. • “Serve and return” interactions build healthy brains. • Genes, environment and experiences shape brain architecture.
Core Concepts in Early Brain and Child Development (cont) • Cognitive, emotional and social development rely on each other. • Early childhood adversity and toxic stress can damage brain architecture. • Positive parenting buffers toxic stress. • Creating right conditions for early child development is more effective and less costly.
Eco-Bio-DevelopmentalModel of Human Health and Disease Biology Physiologic Adaptations and Disruptions Epigenetics Neuroscience The Science of Development Development Learning, Behavior And Health Ecology The social and physical environment Life Course Science Ecologybecomes biology, and together they drive development across the lifespan (Ref 53)
Brains Are Built Over Time, “Bottom-up” • Early experiences are foundation of brain’s architecture. 1. Sturdy - sharp, stable, strong • Fragile - dull, disturbed, diseased • Proliferation 1. 700 new synapses per second • Pruning for efficiency • Sequential neural circuit development • Scaffolding
Serve and Return – Active Ingredient of Experiences • Builds and strengthens brain architecture • Associated with stronger cognitive skills, language development, fewer behavior problems • Quality home environment related to early cognitive & language development, IQ test results and school achievement (Ref 1-10) • Positive childcare relationships associated with better thinking and reasoning skills (Ref 1,6-7)
Serve and Return – Active Ingredient of Experiences • Unreliable, inappropriate, or absent interactions damage brain architecture. • Neglect causes more harm, such as cognitive delays, executive function impairments and disruption of body’s stress response, than physical abuse. (Ref 11-13)
Genes, Environment and Experiences Shape Brain Architecture • Genetics • Blueprint for brain development • Instructs properties of neurons and synapses • Environment 1. Influences quality of brain-building materials 2. Can alter brain’s genetic plan prenatally 3. Healthy – full genetic potential 4. Unhealthy – abnormal neuron properties and aberrant synapses (Ref 14-16)
Genes, Environment and Experiences Shape Brain Architecture • Experiences are child’s interactions with environment. • Low-level, simpler circuits affected prenatally (Ref 15) • Most potent effects postnatally when neural circuits maturing (Ref 17-20) • Can alter genetic plan after neural circuit maturation (Ref 18,21,22) • “Sensitive periods”, as in vision (Ref 23-24), hearing (Ref 25), language (Ref 26)
Disparities in Early Vocabulary Growth Professional Families 1,116 words Working Class Families 749 words Welfare Families 525 words Source: Hart, B. and Risley, T. R. (2003). “The Early Catastrophe: The 30 Million Word Gap by Age 3.”
Early Experiences Alter Gene Expression, Shape Brain • Experience changes brain chemistry. (Ref 33) • Genes altered in “sensitive periods” or throughout life (Ref 34-39) • Epigenetic changes can be inherited. (Ref 40-42) • Positive mastery experience causes epigenetic changes essential for learning. (Ref 43-45)
Early Experiences Alter Gene Expression, Shape Brain • Emotional development biologically wired into brain (Ref 46-50) • Adverse Childhood Experiences (ACE) prime stress system to make hyper-responsive to adversity. (Ref 51) • ACE acts as “signature” releasing genetic predisposition for fear.
Adverse Childhood Experiences • Emotional, physical, sexual abuse • Emotional, physical neglect • Mother treated violently • Household substance abuse • Household mental illness • Parental separation or divorce • Incarcerated household member
Types of Stress Responses • Positive – brief increase in heart rate, mild elevation in stress hormones (shots) • Tolerable – serious, temporary stress response buffered by supportive relationships (death and divorce) • Toxic – prolonged activation of stress response in absence of protective relationships (abuse, chronic neglect, poverty, exposure to violence, parental substance abuse or mental illness)
ACE and Toxic Stress • Brain vulnerability in early “sensitive periods” (Ref 54-55) • Very young can develop debilitating anxiety. (Ref 56) • Mechanisms for ACE changes in brain • Epigenetic “adaptations” • “Wear and tear” releases adrenaline and cortisol • Amygdala detects whether stimulus, person, event is threatening. (Ref 69-70)
ACE and Toxic Stress • Hippocampus links fear response to context of event. (Ref 71) • Pre-Frontal Cortex (PFC) development with Executive Function Skills • Impaired by high stress in animals (Ref 72) • Smaller volume in severe neglect in humans (Ref 73-74) • Neuroplasticity to stress • Early toxic stress results in overly reactive and slow to shut down stress response. (Ref 57-58)
Cortisol Effects • Chronic elevation regulates gene expression in neural circuits for stress response, emotion and memory. (Ref 59) • Chronic elevation alters neural function and brain structure in areas of learning and memory. (Ref 60-61) • Elevated cortisol in economically deprived children & exacerbated when mother depressed (Ref 62-64)
Cortisol Effects • Abnormal cortisol production persists in neglected children after moved to safe, loving home. (Ref 65-66) • In animals, chronic elevation damages hippocampus, affecting learning, memory and stress response regulation. (Ref 67) • Chronic elevation also affects the amygdala.
Effects of Toxic Stress on Learning • Positive stress response strengthens memory formation of emotional events and contexts, blocks unlearning of fear memory. (Ref 81-84) • Toxic stress can impair memory and learning in non-threatening contexts. (Ref 85) • Toxic stress can form emotional memories easily relived and more difficult to forget. (Ref 86-87)
Effects of Toxic Stress on Learning • Toxic stress causes generalization of threat to safe contexts. (Ref 88-89) • Toxic stress builds brain architecture that responds to lower levels of stress with excessive anxiety & fear, causing lifelong effects on mental health. (Ref 90). These mental health effects can impair learning and relating. (Ref 91)
Effects of Toxic Stress on Learning • Toxic stress causes elevated brain noradrenaline which alters activity of neurons in PFC, causing cognitive control and learning problems. (Ref 92-93) • Toxic stress affects Executive Function Skill (EFS) system, the foundation for school readiness and academic success. (Ref 94-95) • Preschoolers with stronger EFS perform better on early math, language and literacy development tests. (Ref 96-103)
Effects of Toxic Stress on Learning • Toxic stress affects EFS (cont) • EFS in economically-deprived preschoolers predicts kindergarten math and reading achievement better than their earlier scores. (Ref 104) – Same for behavior (Ref 105) • EFS connected with deep brain areas that control stress response (Ref 106-108) • EFS system influences and is affected by experiences & management of stress. (Ref 109-110)
Effects of Toxic Stress on Learning • Toxic stress affects EFS (cont) • Toxic stress affects chemistry of brain circuits and alters neurons in EFS system. (Ref 111-114) • Toxic stress causes poor performance on tasks involving working memory and shifting attention. (Ref 115) • Early exposure to stressful environment associated with deficits in working memory, attention and inhibitory control (Ref 116-118)
Effects of Toxic Stress on Learning • Toxic stress affects EFS (cont) • Toxic stress causes difficulty engaging EFS even in safe environs. (Ref 119-120) • Lower socio-economic children have poorer performance on working memory, cognitive flexibility and inhibition, and altered pre-frontal function between ages 7-12 years. (Ref 121-125)
Types and Causes of Dyslexia • Primary dyslexia – absence of brain wiring to left hemisphere posterior reading systems • Genetically programmed error in wiring • 40% chance a sibling, parent, child of affected person will have dyslexia • 5%-6% chance child will have dyslexia if parent/siblings don’t
Types and Causes (Cont) • Secondary dyslexia – lack of activation of normal brain wiring for reading • Environmental deprivation • Economically disadvantaged • ESL students • Struggling readers • Poor school reading instruction
Brain Rewired by Evidence-Based Phonologic Instruction • Functional MRI’s on young struggling readers – left Broca’s area • One year of sequential, explicit, multisensory reading instruction (Orton-Gillingham based) • Repeat fMRI’s - emergence of left posterior, right frontal and right posterior reading systems
Brain Rewired by Evidence-Based Phonologic Instruction (Cont) 4. Repeat fMRI’s one year after instruction ceased – right frontal and right posterior systems much less prominent, increased left posterior systems; fMRI’s essentially same as a non-impaired reader • Children had improved reading accuracy and speed Source: Sally Shaywitz, Overcoming Dyslexia, Alfred A. Knopf, New York, 2003 • Multiple studies have confirmed results
Brain Rewired by Evidence-Based Phonologic Instruction (Cont) 7. Both primary and secondary dyslexics improve with accuracy and speed of reading with appropriate instruction 8. Without appropriate instruction, primary dyslexics can improve accuracy, but remain slow. Secondary dyslexics remain slow and inaccurate
Window of Opportunity • When evidence-based phonologic remedial intervention begun in first grade, expected reading disability of 12% to 18% is reduced to 1.6% to 6% Source: Torgesen, J.K., “Avoiding the Devastating Downward Spiral. The Evidence that Early Intervention Prevents Reading Failure”, 2004 • When this intervention is delayed until third grade, 74% of students continue with reading difficulties through high school Source: American Academy of Pediatrics Technical Report, “Learning Disabilities, Dyslexia and Vision”, March, 2011