Approaches to early detection of learning disabilities in children

1
Approaches to early detection of learning
disabilities in children

• Kenneth R. Pugh, PhD
• President and Director of Research,
• Haskins Laboratories, and
• Associate Professor, Yale University School of
  Medicine

2
Reading development

• The development of fluent reading skill is
  essential for success in the modern world.
• Significant numbers of children in all countries
  fail to acquire adequate literacy skills.
• For many this is due largely to lack of good
  learning opportunities but for some will reflect
  difficulties that are at least in part
  brain-based (Reading Disability).

3
Definitions How to classify RD

• Much controversy on appropriate definitions and
  criteria
• 1) Discrepancy Intuitive but misleading
  criterion.
• 2) Achievement Less confounded but overly
  inclusive.
• 3) Response to Intervention (RTI) Promising but
  needs more research basis.

4
Early identification of risk for RD

• General agreement that phonological processing is
  a core problem in RD.
• Phonological deficits are universal, but what is
  the underlying cause and how early can we detect
  risk for RD?
• Research on pre-school development addresses
  these questions

5
Known Risk Factors for Reading Problems

• Familial (genetic) risk
• Low socioeconomic status
• Less access to print, less stimulating language
  environment, experiential differences
• Developmental speech-language problems
• Specific Language Impairment (SLI) and Speech
  Sound Disorders (SSD)
• Attention and cognitive problems
• Other congenital anomalies
• Hearing impairment, low IQ, many syndromes

6
Types of measures that can serve as early
predictors of risk for RD Behavioral

• 1) key receptive and expressive language measures
• 2) general cognitive, memory, attention, and
  learning measures
• 3) socio-emotional measures

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Prediction Studies Typical Design
Initial Skill Assessment (before formal
reading instruction begins)
K
1st
2nd
3rd
GRADE
PreK
2nd
Outcome Reading Assessment (after 1, 2, or 3
years of formal reading instruction)
r ?
QUESTION How strongly is reading predicted?

8

Jyväskylä Longitudinal study of Dyslexia
(JLD)Results of 12 year follow-up of children
with familial risk for dyslexia from birth
1994-

9
The goals of the JLD

• to identify
• precursors of dyslexia
• predictors of dyslexia
• developmental paths leading to dyslexia
• The next step the development of
  preventive measures

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DEFINING FAMILIAL RISK IN THE JYVÄSKYLÄ
LONGITUDINAL STUDY OF DYSLEXIA (JLD)

• SELECTION CRITERIA FOR THE AT-RISK FAMILIES
  parents
• At least one parent with diagnosed dyslexia from
  multiple criteria
• Reported dyslexia among at least one of the first
  degree relatives
• IQ at least 85 (Raven matrices)
• No reported language problems in childhood or
  later
• No neurological or psychiatric symptoms
• No hearing problems

For detals, see Leinonen et al. Reading and
Writing, 2001
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Current number of children who have attended the
last finished assessment phase at the 2nd grade
Born at the hospitals of Central Finland
during 01.04.93-31.07.96 N 9368 infants
I Screening
II Screening
III Screening
Short questionnaire administered at the
maternity clinics N8427 parents
Compre-hensive questionnaire N3146 parents
AT -RISK GROUP N117 infants
Assessment of parents reading and spelling
skills N410 parents
CONTROL GROUP N105 infants
14 month
II grade
III grade
18 month
2 years
2½ years
3½ years
4½ years
5 years
5½ years
Neo- natal
6 month
6½ years
I grade
Class-
mates N
1515
AT-RISK GROUP N117
N 107
N 107
N 107
N 107
N 107
N 107
N 107
N 107
N 107
N 108
N 107
N 108
N 107
N 112
N 92
N 96
N 94
N 95
N 93
N 93
N 93
N 93
N 92
N 95
N 96
N 94
N 94
N 92
CONTROL GROUP N105
Collection of the data continues
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Familial transmission
Reading
Reading
status of
status of
parents
children
PRECURSOR(S)
PREDICTORS
/ P
such as inaccuracies
such as phonological
in speech perception
skills
Language
Language
development
deficit
Risk
D
EVELOPMENTAL PATHWAY
group
SKILLS
Reading related development


Language Speech perception, phonology
N107


Cognition Comprehension



Motor development


Neuropsychological development

E.g. auditory discrimination, temporal
Interventions
processing, automaticity
Environmental correlates


Parent-child interaction
Control


Exposure to reading
group
Associated characteristics


N93
Co-morbidity / Attention deficit disorders
A
CQUISITION OF COMPENSATORY SKILLS

psychophysiological correlates
Biological /
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• SPEECH PERCEPTION, COMPREHENSION,PRODUCTION
• Auditory discrimination
• Phonological processing
• Vocalization, vocabulary, morphology etc.
• Expressive and receptive language skills

• CHILDS CHARACTERISTICS
• Attention
• Psychophysiological
• Temperament

• INTERVENTION
• Phonological
• Naming
• Family School

• NEUROPSYCHOL. FUNCTIONS
• Visuo-spatial skills
• Articulation, Motor Skills

• COGNITION
• IQ, Memory
• Associative learning

ASSESSMENT DOMAINS

• HOME ENVIRONMENT
• Parent-child interaction
• Print exposure
• Parenting, Stress

• ACHIEVEMENT
• Alphabetic skills
• Reading Spelling
• Math skills

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Is reading acquisition associated with early
language delays?

• Late talking delay in the development of
  expressive language skills (assessed here at 2
  years of age)
• Similar numbers of children in both groups could
  be defined as late talkers
• Do these two groups differ in their later
  language development?
• If so how?
• Is late talking connected to reading acquisition
• If so how?

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Development of language skills among late talkers
of the risk and control groups
1.0
At-risk
Controls
0.5
0
Z-score composite of language skills
-0.5
-1.0
-1.5
2
3 1/2
2
5
3 1/2
5

Lyytinen P. et al., J. of
Speech, Language Hearing Res2001
16
Speech processing deficit?

• Focus Categorical perception of phonemic
  quantity

• Responses to and categorical perception of speech
  sounds at the age of 6 months
• head turn conditioning to syllabic (/ata/
  ../atta/) stimuli
• - categorical perception assessment
• brain event-related potentials (ERP)
• to syllabic /ata/ vs. /atta/ stimuli
  oddball presentation
• and
• to assess sensitivity to quantity (perception of
  duration)

17
Assessing infant categorical perception head
turn conditioning
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The mean percentage of atta-categorizations in
6-month-old infants with high familial risk for
dyslexia and control infants
The groups differ in their responses to /ata/4
(x2 23.32, p .0000) At-risk infants require
longer /t/ (silent gap) duration to categorize
the stimulus as /atta/
Richardson et. al., 2003 Developmental
Neuropsychology .
19
Observing developmental routes to dyslexia

• Predictive domains ages 1-6.5 years
  Alpha
• Receptive language 12, 14, 18 mo, 2.5, 3.5, 5
  y .78
• Expressive language 12, 14,18 mo, 2.0, 2.5,
  3.5, 5.5 y .93
• Morphology
  2.5, 3.5, 5.0 y .76
• Verbal short term memory 3.5,
  5.0, 5.5, 6,5 y .75
• Rapid serial naming
  3.5, 5.5, 6.5 y .89
• Letter knowledge
  3.5, 4.5, 5.0, 6.5 y .72
• Phonological skills 3.5, 4.5, 5.5, 6.5 y
  .82
• IQ
  5.0
• Outcome measures used as a composite
• Reading accuracy (Aug., Jan., May), Fluency
  (Aug., Dec., April, May/1 gr, Nov/2.gr), Spelling
  (Dec., Apr,/1.gr Nov/2.gr)
• Comprehension (Apr./1gr. And Nov/2.gr)
  

Lyytinen et al., Merrill-Palmer Quarterly, 2006
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IDENTIFYING PREDICTING RISK a summary of
significant measures
P Predictors D Differences between groups
Age Variable
7 - yrs Reading accuracy speed D 5
- yrs Naming speed P D 4 - 6 yrs
Phonological manipulation P D 5 - 6 yrs Letter
knowledge P D 5 - yrs Verbal memory P
D 3 - 6 yrs Phonological sensitivity P D 3 -
5 yrs Inflectional skills P D 2 - 3 yrs
Articulation accuracy P 2 yrs Maximum
sentence length P D 6 mth Speech
perception P D Birth ERP to speech sound
P D
Lyytinen et al., Annals of Dyslexia, 2004
Dyslexia, 2004 Sage Handbook of Dyslexia, 2008
21
Precursors/predictors interim conclusions fro JLD

• Familial background increases the risk of
  dyslexia substantially relatively the more so,
  the more severe reading difficulties are attended
• Speech perception is predictive from 6 months and
  does so at school age still after controlling
  for other known predictors
• Very early language delays can be informative,
  both in the expressive and receptive language
  domains but receptive language may be more
  important
• Poor letter name learning predicts without false
  negatives (false positives should be accepted)
• Dysfluent naming predicts the most persistent
  difficulties
• also when the phonological skills revealed
  by traditional assessment tools fail to predict

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John Locke, Lehman College, CUNY Paul Macaruso,
Haskins Laboratory, Rhode Island Community
College, MGH-IHP, Jim Hodgson, Middle Tennessee
State University Jenny Roberts, Hofstra
University Susan Lambrecht Smith, University of
Maine Allan Smith, University of Maine
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Longitudinal Exploration 24-36 Months
25

• Participants were selected from the original
  precursors group at age 30 months
• 9 children identified with RD
• 9 normally reading children at high familial risk
  for RD
• 10 normally reading children at low risk for RD

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• Phonetic phrase
• Speaking turns bounded by speech of others and
  with no pause more then 2.5 s
• Pauses
• Silent intervals of 250ms to 2.5 s
• Speaking rate
• 1. Syllables per second
• Sum of phonetic phrase durations/number of
  syllables
• 2. Proportion of pausing time
• Sum of pause duration/sum of phonetic phrase
  duration
• 3. Articulation rate
• Syllables per second - pauses

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p lt .05
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p lt .01
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• Phonological and lexical characteristics of
  30-month-old childrens spontaneous language
  samples were examined as indicators of later
  reading outcome.
• Participants were 27 children, 10 children with
  reading disability and 17 children without
  reading disability. Of the non-disabled readers,
  7 were at high familial risk for reading
  disability, and 10 came from families with no
  history of reading difficulties.

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• Lexical diversity
• percentage of different words in the first 250
  words (NDW) of each childs transcript,
• percentage of different polysyllabic words (NDPW)
  in that 250-word sample.
• Phonological complexity (also calculated using
  the first 250 words)
• percentage of word that were polysyllabic
• the mean number of consonant clusters per word
• Ingrams (2002) measure of phonological mean
  length of utterance (PMLU

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• Findings Children later identified as reading
  disabled at second grade and beyond as toddlers
  showed
• Poor speech motor control
• narrower lexical diversity and simpler
  phonological forms as compared to the normal
  reading participants.

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Meta-Analysis Predicting Future Reading from
Kindergarten Skills (Results from 61 studies
published 1976-1996)
r
Predictor
mdn M
.53 .52 .49 .46 .42 .46 .49 .45 .49 .45 .38
.41 .40 .38 .40 .37 .33 .33 .38 .33 .37
.32 .28 .31 .25 .26 .25 n.a. .23 .22 .19 .21
Letter Identification Concepts of
Print Phonological Awareness Expressive
Vocabulary Sentence/Story Recall Full-scale or
Verbal IQ Rapid Serial Naming Receptive
Language Word/Digit Memory Receptive
Vocabulary Expressive Language Visual
Memory Performance IQ Speech Production/Artic. Spe
ech Perception Visual Motor Skills
Many predictors have been studied.
AND About 89 of reading outcomes can be
correctly predicted by a small set of skills in
kindergarten.
Scarborough (1998)
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Meta-Analysis Predicting Future Reading from
Kindergarten Skills (Results from 61 studies
published 1976-1996)
r
Predictor
mdn M
.53 .52 .49 .46 .42 .46 .49 .45 .49 .45 .38
.41 .40 .38 .40 .37 .33 .33 .38 .33 .37
.32 .28 .31 .25 .26 .25 n.a. .23 .22 .19 .21
Letter Identification Concepts of Print Phonol.
Awareness Expressive Vocab. Sentence/Story
Recall Full-scale or Verbal IQ Rapid Serial
Naming Receptive Language Word/Digit
Memory Receptive Vocab, Expressive
Language Visual Memory Performance IQ Speech
Production Speech Perception Visual Motor Skills
PRINT SKILLS
ORAL LANGUAGE including phonological
skills (in pink)
SPEECH
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Foundational Skills for Early Literacy

• Alphabet Knowledge
• Phonological Awareness
• Rapid Automatic Naming of letters, digits,
  objects, colors
• Writing letters, name
• Phonological memory
• Moderate correlations Concepts about Print
  (left-right, book cover, etc.), print knowledge,
  reading readiness, oral language, visual
  processing
• (based on National Early Literacy Panel)

37
Birth to five summary (behavioral) Risk for
Reading Disability

• Language milestones early on are critical for
  adequate reading development later on
• 1) Early receptive and expressive language
  development predicts reading acquisition.
• Phonological Awareness is critical in
  preschoolers.
• Key Enriched pre-school exposure to
  phonological (spoken language) and simple
  orthographic experience is very important in
  potentially preventing later reading difficulties.

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Complex relation between risk factors and
environment

• Pre- and post natal environment is crucial to
  later language and reading development.
• Major environmental factors that can compound
  congenital risk factors include
• 1) Mother/infant nutrition.
• 2) Pre-natal drug, nicotine, and alcohol
  exposure.
• 3) Neglect and lack of early stimulation of
  language and learning.

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Implications environment by risk interactions

• So, we must pay attention to the ways in which
  the environment we create makes things better or
  much worse for children at risk for RD.
• Stimulation of expressive and receptive language
  is crucial

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Classes of measures that can serve as early
predictors of risk for RD Neurobiology

• Genetics
• Structural and functional brain imaging
• Potential advantages of neurobiological
  measures increased sensitivity and early
  detection of risk

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Jyväskylä Longitudinal study of Dyslexia (JLD)
EEG findings

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METHODS ERP recording
From F3, F4, C3, C4, P3, P4 (Ag/AgCl-electrodes),
referred to ipsilateral mastoid Bandpass
0.5-35 Hz, sampling rate 200 Hz
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ERP difference waves between responses to
repeated standard and infrequently presented
deviant /ata/s (i.e. deviant-standard response).
Note that the deflection of negative polarity
called mismatch negativity (MMN) is present in
both groups in the right hemisphere but is
clearly smaller in the left hemisphere among at-
risk children (from Leppänen Lyytinen, 1997
Leppänen et al. 2002).
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JLD EEG findings

• Speech processing from birth
• ERPs to speech sound differ between children
  with and
• without familial risk for dyslexia at 3-5 days
  of age and
• predict language development and reading
  acquisition
• Categorical perception from very early age
• ERPs and behavioral responses to phonemic
  duration
• differ from age 6 months
• Key outcome in school aged kids Speech
  perception is predictive from 6 months and does
  so at school age still after controlling for
  other known predictors

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Haskins/Yale Longitudinal Study (Pugh et al.,
2009)

• We need to examine development longitudinally
  with integrated brain/behavior designs.
• We have two ongoing NIH funded longitudinal
  studies asking What are the behavioral and
  neurobiological preconditions for successful
  literacy acquisition?
• Study 1) from 7-9 years examines at risk children
  with multiple levels of analysis (genetics,
  neuroanatomy, neurochemistry, neurocircuitry,
  behavior).

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Effects of Early Language Development

• Several studies of late talkers have suggested
  residual deficits in reading in young school-age
  children (Rescorla 2002, 2005, 2009 Scarborough
  Dobrich, 1990 JLD project 2005)
• Parents complete questionnaire on child/family
  background and childs development
• Asked to report on when child began to Speak 2-3
  word sentences.
• Parent rated child as Early, On Time or Late

48
Talker Group Comparisons on Reading
MeasuresWoodcock-Johnson Tests of Achievement
49
Talker Group Comparisons on Reading
MeasuresWoodcock-Johnson Tests of Achievement
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Talker Group Comparisons on Reading
MeasuresGray Oral Reading Test (GORT)
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Late talking and brain organization for literacy
acquisition

• How do children with higher reading readiness
  differ in initial brain organization for print
  and speech at age 7?

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Late versus early talkers Brain activation in
reading and speech at at 7.5
p lt .025, FDR corrected
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Key finding

• Neurobiological problems in sub-cortical
  motor/perceptual learning circuits may be an
  important early risk marker for later reading
  disability.

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Phonemic awareness and speech/print integration
(Frost et al. 2009)

• Phonemic awareness scores reflect reading
  readiness low PA is a strong risk factor for RD.
  
• How do children with higher reading readiness
  differ in initial brain organization for print
  and speech at age 7?

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Modality Effects
gtPrint gtSpeech Overlap
p lt .001
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PA x Modality

p lt .01
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PA x Modality

r 0.44
p lt .01
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Correlation of PA with BOLD Modality Effect
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Key finding

• This finding suggests that children who are
  developing normally in reading modify brain
  systems for spoken language processing to become
  available for processing visual graphemes.
• Key Neuroimaging studies of these critical brain
  systems early on may help identify risk before
  reading fails

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Next steps Better understanding of the brain

• Neurobiological measures provide mediating levels
  of analysis between gene and behavioral
  phenotype.
• 2) Sensitivity A potentially deeper account of
  individual differences in either typical or
  atypical development and individual differences
  in optimal intervention strategies for at-risk
  children. What works for whom.
• 3) Early detection of biomarkers predictive of
  risk for atypical development.

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Beyond identification of risk for RD

• What can we do to give at-risk children a better
  reading and academic outcome?

64
Foundational Skills for Early Literacy

• Alphabet Knowledge
• Phonological Awareness
• Rapid Automatic Naming of letters, digits,
  objects, colors
• Writing letters, name
• Phonological memory
• Moderate correlations Concepts about Print
  (left-right, book cover, etc.), print knowledge,
  reading readiness, oral language, visual
  processing
• (based on National Early Literacy Panel)

65
Current Intervention Paradigms for (Pre-)Readers

• Basic Phonological Awareness Training
• Awareness of syllables, onsets, rhymes, phonemes
• Blending segmenting parts of words
• Matching words based on phonological
  characteristics
• Substantial research demonstrating effectiveness
  for preschoolers, especially for individual and
  small group instruction (e.g., Van Kleeck et al.,
  1998)
• Phonological Awareness Training Beyond the
  Basics
• Move quickly to phoneme-level awareness, rather
  than rhyme-level awareness (Nancolis et al.,
  2005)
• Focus on articulatory gestures associated with
  phonemes, rather than phonemes as isolated units
  (Castiglioni-Spalten, Ehri, 2003)
• PA training plus letter-sound correspondence is
  preferred (Ball Blachman, 1991)
• Incorporating PA training and letter knowledge
  into speech-language therapy reduces the risk of
  later literacy problems (Gillon 2000, 2005)

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Current Intervention Paradigms for (Pre-)Readers

• Language-Based Intervention in Preschool
• Dialogic reading to support vocabulary,
  comprehension, interest (Whitehurst et al., 1994,
  1998)
• Asking open-ended questions, following childs
  answers with questions, repeating and expanding
  on what child says, offering praise,
  encouragement and feedback for participation,
  following childs interest
• Print Referencing to support letter knowledge
  (Ezell Justice, 2000)
• Ask questions about print, pose questions about
  print, make comments about print, point to print

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Collaborators

• Haskins Laboratories Einar Mencl, Rebecca
  Sandak, Stephen Frost, Dina Moore, Nicole Landi,
  Leonard Katz, Jay Rueckl, Jim Magnuson, Donald
  Shankweiler, Jun Ren Lee, Carol Fowler, Alvin
  Liberman
• Yale Reading Center Ken Pugh (Director), Gina
  Della Porta, Eleanor Tejada, Kelley Delaney,
  Ashley Zennis, Priya Pugh,
• Yale Center for the Study of Learning and
  Attention Bennett Shaywitz, Sally Shaywitz,
  Karen Marchione, John, Holahan, Jack Fletcher
• Yale University/Diagnostic Radiology John Gore,
  Todd Constable, Robert Fulbright, Doug Rothman,
  Graeme Mason, Pawel Skudlarski, Cheryl Lacadie
• Yale University/Psychiatry Leslie Jacobsen
• Yale Child Study Center Elena Grigorenko