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

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).

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.

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

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…

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

Prediction Studies: Typical Design

K 1st 2nd2nd 3rdGRADE: PreK

Initial Skill Assessment(before formal readinginstruction begins)

Outcome Reading Assessment(after 1, 2, or 3 years of

formal reading instruction)

r = ?

QUESTION: How strongly is reading predicted?

Jyväskylä Longitudinal study of Dyslexia (JLD)

Results of 12 year follow-up of children with familial risk for dyslexia from birth

1994-

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

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

N=

108

N=

107

N=

107

N=

107

N=

107

N=

107

N=

95

N=

96

N=

94

N=

95

N=

93

N=

93

18 month

2 years

2½ years

3½ years

4½ years

5years

5½ years

N=

107

N=

93

Collection of the data continues

N=

108

N=

107

N=

112

Neo-natal

6 month

14 month

N=

96

N=

94

N=

94

6½ years

N=

107

N=

93

Igrade

IIgrade

N=

107

N=

92

IIIgrade

N=

107

N=

92

Class- mates

N =

1515

N=

107

N=

92

I Screening II Screening III Screening

Short questionnaire administered

at the maternity

clinics

N=8427 parents

Compre-hensive

questionnaire

N=3146 parents

Assessment of parents’

reading and spelling skills

N=410 parents

AT -RISK GROUP

N=117 infants

CONTROL GROUP

N=105 infants

Born at the hospitals of

Central Finland during

01.04.93-31.07.96

N= 9368 infants

Current number of children who have attended the last finished assessment phase at the 2nd grade

AT -RISK GROUP

N=107 infants

CONTROL GROUP

N=92infants

AT-RISK GROUP

N=117

CONTROL GROUP

N=105

Riskgroup

N=107

Controlgroup

N=93

Readingstatus ofparents

Readingstatus ofchildren

Familial transmission

ACQUISITION OF COMPENSATORY SKILLS

DEVELOPMENTAL PATHWAY

SKILLSReading related development Language Speech perception, phonology Cognition Comprehension Motor development Neuropsychological development E.g. auditory discrimination, temporal

processing, automaticity

Environmental correlates Parent-child interaction Exposure to reading

Associated characteristics Co-morbidity / Attention deficit disorders

/ P

such as inaccuraciesin speech perception

such as phonologicalskills

Languagedeficit

Languagedevelopment

Biological / psychophysiological correlates

Interven

tions

PRECURSOR(S) PREDICTORS

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

ACHIEVEMENT• Alphabetic skills• Reading & Spelling• Math skills

CHILD’S CHARACTERISTICS• Attention• Psychophysiological• Temperament

COGNITION• IQ, Memory• Associative learning

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

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

INTERVENTION• Phonological• Naming• Family School

ASSESSMENT DOMAINS

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?

-1.5

-1.0

-0.5

0

0.5

1.0

Development of language skills among late talkers of the risk and control groups

2 3 1/2

Z-score composite of language skills

2 5

Not late talkers

Late talkers

Not late talkers

Late talkersAge (years)

3 1/25

At-risk Controls

Lyytinen P. et al., J. of Speech, Language & Hearing Res;2001

Speech processing deficit?

• 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)

• Focus: Categorical perception of phonemic quantity

Assessing infant categorical perception: head turn conditioning

Infants were conditioned to turn their heads towards a visual reinforcer whenever they perceived a change within the /ata/ – /atta/ sequence.

Head turns to /atta/ (atta8) were visually reinforced using an animated toy during conditioning phase.

During the testing phase the original word /ata/ (stimulus ata1) was repeated with all variants of the “second stimuli” which had longer t-sounds in the change trials.

The mean percentage of atta-categorizations in 6-month-old infants with high familial risk for

dyslexia and control infants

1 2 3 4 5 6 7 8 0

10

20

30

40

50

60

70

Mean

% of Head Turns

Stimuli continuum /ata/1 - /ata/ 8

At-risk infants

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 .

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

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

IDENTIFYING & PREDICTING RISKa summary of significant measures

P = Predictors D = Differences between groups

Lyytinen et al., Annals of Dyslexia, 2004; Dyslexia, 2004; Sage Handbook of Dyslexia, 2008

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

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

Longitudinal Exploration 24-36 Months

• 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

• 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

p < .05

Proportion of Pause Time

0

0.02

0.04

0.06

0.08

0.1

0.12

RD

HR-NRNR

p < .01

Articulation Rate

2.2

2.3

2.4

2.5

2.6

2.7

2.8

Syllables Per Second

RD

HR-NRNR

• Phonological and lexical characteristics of 30-month-old children’s 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.

• Lexical diversity– percentage of different words in the first 250 words (NDW) of

each child’s 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– Ingram’s (2002) measure of phonological mean length of

utterance (PMLU

Phonological Complexity

0

2

4

6

8

10

12

14

16

18

Percent Polysyllable words CC per word

RD

NR-RNR

*

Findings: Children later identified as reading disabled at second grade and beyond as toddlers showed:

1) Poor speech motor control

2) narrower lexical diversity and simpler phonological forms as compared to the normal reading participants.

r

.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

.00 .05 .10 .15 .20 .25 .30r =2

mdn M Predictor

Scarborough (1998)

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.

Speech Perception

Visual & Motor Skills

Meta-Analysis: Predicting Future Reading from Kindergarten Skills(Results from 61 studies published 1976-1996)

Many p

redict

ors

have b

een

studie

d. AND:About 89% of reading outcomescan be correctly predicted by a small set of skills in kindergarten.

r

.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

.00 .05 .10 .15 .20 .25 .30r =2

mdn M Predictor

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

ORAL LANGUAGE including phonological skills (in pink)

PRINT SKILLS

Meta-Analysis: Predicting Future Reading from Kindergarten Skills(Results from 61 studies published 1976-1996)

SPEECH

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)

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.

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.

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

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

1) Genetics2) Structural and functional brain imaging

* Potential advantages of neurobiological measures: increased sensitivity and early detection of risk

Jyväskylä Longitudinal study of Dyslexia (JLD); EEG findings

From: F3, F4, C3, C4, P3, P4 (Ag/AgCl-electrodes), referred to ipsilateral mastoid

Bandpass: 0.5-35 Hz, sampling rate 200 Hz

METHODS – ERP recording

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).

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

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).

Timeline Time 1 (7.5 yrs of

age) Time 2 (8.5 yrs of

age) Time 3 (9.5 yrs of

age) Cohort 1 (N= 54) Year 1-3

DNA, MRS, fMRI, Behavior

Behavior fMRI, Behavior

Cohort 2 (N= 54) Year 2-4

DNA, MRS, fMRI, Behavior

Behavior fMRI, Behavior

Cohort 3 (N= 54) Year 3-5

DNA, MRS, fMRI, Behavior

Behavior fMRI, Behavior

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 child’s development– Asked to report on when child began to “Speak 2-3

word sentences.” – Parent rated child as Early, On Time or Late

Talker Group Comparisons on Reading Measures:

Woodcock-Johnson Tests of Achievement

Talker Group Comparisons on Reading Measures:

Woodcock-Johnson Tests of Achievement

Talker Group Comparisons on Reading Measures:

Gray Oral Reading Test (GORT)

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?

EARLY > LATELATE > EARLY

p < .025, FDR corrected

Late versus early talkers Brain activation in reading and speech at at 7.5

THALAMUS

PUTAMEN

SUPERIOR TEMPORAL GYRUS

SPEECH PRINT

Key finding

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

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?

Modality Effects

p < .001

>Print>Speech Overlap

PA x Modality

p < .01

p < .01

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

-2.5 -1.5 -0.5 0.5 1.5

Phonological Awareness

Activation

Speech

Print

PA x Modality

r = 0.44

Correlation of PA with BOLD Modality Effect

STG

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

Low PA High PA

B-weight

Auditory

Visual

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

Next steps: Better understanding of the brain

1) 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.

Beyond identification of risk for RD

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

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)

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)

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 child’s answers with questions, repeating and expanding on what child says, offering praise, encouragement and feedback for participation, following child’s 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

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