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Developmental language disorder and auditory processing disorder: 
Same or different?


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Presentation at course on Auditory Processing, Language and Cognition. Ear Institute, UCL. March 2018

Published in: Education

Developmental language disorder and auditory processing disorder: 
Same or different?

  1. 1. 1 Developmental language disorder and auditory processing disorder: Same or different? Dorothy V. M. Bishop Department of Experimental Psychology, University of Oxford
  2. 2. Overview of talk Using my own research to illustrate some key points about overlaps between APD, DLD, dyslexia • Studies comparing those with different diagnoses – Children diagnosed with APD often have language problems – Children diagnosed with DLD/dyslexia often have auditory problems • Can we devise auditory processing measures that aren’t affected by language measures? – No! Even passive electrophysiological measures can be influenced by language • Can we confirm that auditory deficit has causal role? – Causal models suggest apparent APD can be consequence of language disorder – No good evidence that auditory interventions benefit language 2
  3. 3. Part 1 Evidence that the same child may have features of APD, DLD, dyslexia, ADHD or autism spectrum disorder Specific diagnosis may depend on who they see 3
  4. 4. Hypothetical 9-yr-old: George 4 • Late to start to talk • Episodes of otitis media with effusion as a toddler • Otherwise developed normally • Now struggling at school • Doesn’t always remember what his teacher says • Complains that people talk too fast for him to understand • Parents think he may have APD and seek referral to audiologist
  5. 5. Audiological evaluation 5 • Normal peripheral hearing • Low score on competing words dichotic listening (SCAN-3) • Low score on auditory figure- ground
  6. 6. Psychological/language assessment 6 • Nonverbal IQ of 103 • Vocabulary and comprehension levels are lower, with scaled score equivalents of 85 • Poor scores on tests of verbal memory • Reading ability is at a 7-year-old level
  7. 7. George’s diagnosis depends on who makes it 7 Same child diagnosed with: • Auditory Processing Disorder (APD) by audiologist • Developmental Language Disorder (DLD)* by speech/language therapist • Developmental dyslexia by educational psychologist * Previously referred to as Specific Language Impairment (SLI) Is this anecdote backed up by data?
  8. 8. Study comparing children diagnosed with APD vs those diagnosed with dyslexia 25 children with APD diagnosis • recruited from audiology clinics based at four hospitals in the UK. All of these children had been diagnosed on basis of – complaint of listening difficulties, – normal peripheral hearing – score below clinical cut-off on the SCAN-C or-A9 10 plus – failed on at least one non-speech test of auditory processing 19 children diagnosed with dyslexia by educational psychologist – reading or spelling test standard score > 1 SD below mean – non-verbal IQ greater or equal to 80 • Direct assessments of language and literacy, SCAN-C • Parent questionnaires: language, behaviour, listening, autistic features 8Dawes & Bishop (2010) Psychometric profile of children with auditory processing disorder and children with dyslexia. Archives of Disease in Childhood, 95, 432-436.
  9. 9. • Parent rating of communication on CCC-2 was also surprisingly low, suggesting autistic features; • Subset given Childhood Asperger Syndrome test; 6/18 APD and 0/12 dyslexic above threshold for ‘possible clinical case’ 9 Percentages meeting diagnostic criteria APD N = 25 Dyslexia N = 19 Developmental Language Disorder 52% 58% ADHD 37% 46% APD (borderline+ on SCAN) 40% 22%
  10. 10. Conclusions: APD vs dyslexia Surprisingly small number of APD cases did poorly on SCAN-C – we used own UK norms. Concern that current test batteries may over- diagnose APD Considerable overlap in symptoms – variable neurodevelopmental problems in both groups. Parent report of communication problems was high, even taking into account language/literacy test scores: Autistic-like communication problems related to APD APD more like a variable correlate of neurodevelopmental disorders (including DLD, dyslexia, ADHD, ASD) than a distinct syndrome 10
  11. 11. Does specific diagnosis matter? Yes. Has implications for intervention 11
  12. 12. 12 Auditory processing disorder Poor speech discrimination Broader language deficits Implicit in diagnosis of APD: Language/literacy problems as downstream consequence of low-level perceptual deficit Intervention
  13. 13. Auditory processing Phonetic feature extraction Phonological analysis Word recognition 13 Typical ’bottom-up’ model of auditory/phonological processing Bishop, D. V. M. (1997) Uncommon understanding: Development and disorders of language comprehension in children
  14. 14. Auditory processing Phonetic feature extraction Phonological analysis Word recognition 14 Phonological processing influenced by top-down knowledge Higher-level language knowledge
  15. 15. Fail auditory processing tests Poor language skills Alternative possibility
  16. 16. Fail auditory processing tests Poor language skills Suggests auditory intervention won’t be effective in improving language: Need direct language intervention Intervention
  17. 17. Part 2 Can we develop pure measures? 17
  18. 18. Can we devise auditory measures that are not contaminated by language level? Many APD tests hard to interpret • Use of verbal stimulus materials – Poor performance could be result of limited language skills • Verbal strategies with nonverbal tasks – Implicit or explicit verbal labelling of stimuli 18
  19. 19. - P1 N1 P2 N2+ FZ 100 ms 1 µV An alternative approach: Electrophysiological rather than behavioural measures • More direct measure of brain response • Passive paradigm: Less likely to be influenced by motivation, strategy, etc • But: Cannot assume ERPs won’t be affected by prior language experience (as I will show later!) Auditory ERP (event-related potential)
  20. 20. Other disadvantages of auditory ERPs Lack good psychometric properties: • Little known about what is typical at given age (means/variances) • Some indices have poor reliability (especially with children – but seldom tested) • Little consistency across labs • Seldom correlate with behavioural measures
  21. 21. Conclusions from a review of mismatch negativity and language/literacy problems Scope for ‘false positive psychology’ • Post hoc decisions re: • Which electrode(s) to use • Which time window • How to filter • Artefact rejection • Averaging or peak measurements Simmons, J. P., Nelson, L. D., & Simonsohn, U. (2011). False-positive psychology: undisclosed flexibility in data collection and analysis allows presenting anything as significant. Psychological Science, 22(11), 1359-1366. Bishop, D. V. M. (2007) Using mismatch negativity to study central auditory processing in developmental language and literacy impairments: where are we, and where should we be going? Psychological Bulletin, 133, 651-672
  22. 22. 22 If we are going to develop a clinically-useful ERP measure, need to focus on findings that are replicable across labs and samples
  23. 23. 23 A candidate for an auditory ERP component that is related to language disorder and seems to replicate: the T-complex
  24. 24. • T-complex: AERP recorded from temporal sites ; generated in secondary auditory cortex, • Lateralised with a right-sided predominance • T-complex has a different developmental trajectory to the vertex response • Matures early and remains relatively constant from puberty onwards
  25. 25. Shafer, Schwartz & Martin, 2011 Experiment 1: 12 typically developing vs 8 DLD (SLI)
  26. 26. Shafer, Schwartz & Martin, 2011 • Re-analysis of data from four ERP studies on DLD • Stimuli: words or vowel sounds • 22 children with DLD, 31 typically-developing controls • Absent/weak T-complex in 73% DLD vs. 13% typical Seemed worth looking at T-complex in our data
  27. 27. Mervyn Hardiman Can we replicate T-complex abnormality in DLD, and if so, is it specific to speech stimuli? Stimuli: 1000 Hz tone or /ba/ syllable, both 175 ms Johanna Barry
  28. 28. Participants • 32 children aged 7 to 11 yr • 16 with DLD • 16 matched TD controls • 32 teenagers aged 12 to 15 yr • 16 with DLD • 16 matched TD controls DLD and typically developing (TD) matched on age, sex and nonverbal IQ
  29. 29. ERP at temporal sites: 1000 Hz tone: reduction in T-complex in DLD children and teens (grey) vs controls (black) Children Teens TD DLD LEFT RIGHT
  30. 30. ERP at temporal sites: Syllable ‘ba’: Large reduction in T- complex in DLD Children Teens TD DLD LEFT RIGHT
  31. 31. Categorical classification • Tone condition: – 8 TD cases vs 17 DLD cases had no Ta • Speech condition – 8 TD cases vs 20 DLD cases had no Ta • Similar to Shafer et al: Highly significant difference, but absence of Ta is not a reliable marker for DLD; • Cases of no Ta in controls raises question about whether absent Ta reflects cause of language disorder
  32. 32. 32 Does T-complex predict children’s language skills?
  33. 33. Test for Reception of Grammar The elephant pushing the boy is big Receptive and phonological measures selected as most likely to relate to auditory ERP
  34. 34. Test for Reception of Grammar The elephant pushing the boy is big NEPSY nonword repetition Child repeats nonwords presented by audio recording e.g. skriflunaflisstrop detratapillic Scored by N syllables correct Receptive and phonological measures selected as most likely to relate to auditory ERP
  35. 35. Test for Reception of Grammar The elephant pushing the boy is big NEPSY nonword repetition Child repeats nonwords presented by audio recording e.g. skriflunaflisstrop detratapillic Scored by N syllables correct NEPSY oromotor sequences Repeat ‘tongue-twisters’ five times each e.g. “scoobelly doobelly” “put the pepper beads in the paper bag” Receptive and phonological measures selected as most likely to relate to auditory ERP
  36. 36. Test for Reception of Grammar The elephant pushing the boy is big NEPSY nonword repetition Child repeats nonwords presented by audio recording e.g. skriflunaflisstrop detratapillic Scored by N syllables correct NEPSY oromotor sequences Repeat ‘tongue-twisters’ five times each e.g. “scoobelly doobelly” “put the pepper beads in the paper bag” TOWRE phonemic decoding Speeded reading of nonwords Receptive and phonological measures selected as most likely to relate to auditory ERP
  37. 37. Does Ta amplitude predict language/literacy? 1 2 3 4 1 Tone T7 1 2 Tone T8 0.66 1 . 3 Syllable T7 0.63 0.44 1 4 Syllable T8 0.36 0.66 0.56 1 5 TROG-2 0.07 0.03 0.24 0.08 6 Nonword rep 0.25 0.32 0.31 0.37 7 Nonword read 0.22 0.29 0.36 0.31 8 Oromotor 0.18 0.20 0.36 0.27 z-scores (age corrected) Correlations in orange show that the T complex measures tend to be intercorrelated Yellow correlations are significant associations between T complex measures and language measures
  38. 38. Part 3 Distinguishing causal relationships 38
  39. 39. Poor T-complex Poor language skills But correlation does not indicate direction of causation B Poor T-complex Poor language skills A T-complex may arise as brain becomes proficient in language learning
  40. 40. 40 PLoS ONE 12(3): e0171992. doi:10.1371/journal.pone.0171992 The results revealed differences in temporal AEPs (Na and Ta of the T-complex) between monolingual and bilingual children. Specifically, bilingual children showed smaller and/or later peak amplitudes than the monolingual groups. ….Amount of experience and type of experience with the target language (English and German) influenced processing. Evidence that T-complex can be affected by language experience
  41. 41. 41 Correlation between parent LI and child LI = x.y If x = 0, then predict no parent/child covariance Indexed by parental language scores Indexed by Ta component of auditory ERP in child Indexed by child language scores We can help disentangle cause by considering data on parental language
  42. 42. 42 Language disorder tends to be familial: parent and child language correlated
  43. 43. 43 Parent Tone L Tone R Syll L Syll R 9 TROG-2 0.14 0.12 0.08 0.00 10 Nonword rep 0.13 0.14 0.06 0.12 11 Nonword read 0.11 0.13 0.11 0.09 12 Oromotor 0.30 0.38 0.30 0.41 Child auditory ERP, Ta Correlations between child Ta and parent language measures Parent language measures that correlate with child language don’t correlate with child auditory ERP: Endophenotype model does not fit
  44. 44. 44 If abnormal Ta (auditory deficit) is a consequence of language disorder Covariance between parent LI/child auditory = y.z; Will be small but positive Parent measure Child measures A different causal model …..
  45. 45. 45 POOR FIT POOR FAIR GOOD FIT Pattern of correlations fits Neuroplasticity model better than Endophenotype – i.e. looks as if T- complex abnormality may be a marker of poor language, but not a cause
  46. 46. T-complex study: conclusions • Replicated abnormal T-complex in SLI • Topography as well as amplitude abnormal for syllable ‘ba’ • Inclusion of parental data provides way of testing between causal models • In this dataset, results gave best fit to model in which language impairment influenced how brain responds to auditory signals • Even a passive, neurophysiological measure may be influenced by language ability
  47. 47. What would be evidence for auditory causal model? • Show that auditory-focused intervention improves language skills 47
  48. 48. 48 Auditory intervention for language problems • Fast transitional elements amplified and stretched  FastForWord® - computerised training – Developed by Tallal and colleagues; – Very intensive; 90 min x 5 day/wk x 6 wk – Uses speech that is modified to make brief/low intensity portions more salient
  49. 49. 49 FastForWord® : studies of effectiveness Meta-analysis combining results from six high- quality trials found FFW group did no better than control group “None of the 8 pooled effect sizes were reliably different from zero, and 4 of the effect sizes were actually negative (indicating worse performance in the Fast ForWord treatment group than the control group).” Strong, G. K., et al. (2010). A systematic meta-analytic review of evidence for the effectiveness of the ‘Fast ForWord’ language intervention program. Journal of Child Psychology and Psychiatry, 52(3), 224-235.
  50. 50. Might auditory manipulation still be effective?  Auditory training is only part of the FFW package  Some children who were given the intervention had no problems with auditory discrimination
  51. 51. Bishop, Rosen & Adams, 2006 Questions • Can computerised training improve comprehension in children with receptive language problems? • If so, does speech modification help? • Does child’s auditory processing status make a difference? Bishop, D. V. M., Adams, C. V., & Rosen, S. (2006). Resistance of grammatical impairment to computerized comprehension training in children with specific and non- specific language impairments. International Journal of Language and Communication Disorders, 41, 19-40. Stuart Rosen UCL Caroline Adams Oxford
  52. 52. Design of study Group S: trained with regular speech Group M: trained with modified speech Group U: untrained • Language assessment • Auditory discrimination test • Comprehension training (less intensive than FFW)
  53. 53. • Game measures ability to distinguish direction of tone glides • Difficulty increased by making sounds closer in frequency • Adaptive threshold estimation; unpaced presentation
  54. 54. Comprehension training
  55. 55. Child hears sentence and must move objects on screen to match. Fast/correct responses rewarded with exciting feedback
  56. 56. Amount of training group S N = 12 group M N = 12 sessions: mean (SD) 14.50 (7.57) 16.00 (7.90) range 6-26 6-29 trials: mean (SD) 1162 (847) 1162 (646) range 243-2529 289-2191 Normal Modified speech speech
  57. 57. Time 2 : retest • Average of 80 days after time 1 • Same battery of standardized language tests • Parallel forms used
  58. 58. TROG-2 scores 50 55 60 65 70 75 80 85 Group S N = 12 Group M N = 12 Group U N = 9 drop-out N = 3 scaledscore pretest posttest • All groups improved; • No effect of training or speech modification • Improvement unrelated to amount of training • Improvement unrelated to initial auditory scores
  59. 59. What have we learned? • Many children with receptive language disorders don’t have the auditory processing problems postulated by Tallal’s theory • No relationship between auditory impairment and learning • On a task that doesn’t tax auditory perception, learning occurs but it is very very slow. Suggests main problem is with language learning processes, rather than auditory processing
  60. 60. Overview: Implications for APD • Classic APD measures may not be measuring primary auditory deficit • APD is a symptom: not a coherent syndrome • Need to consider top-down impact of language disorder on test performance – even when electrophysiological measures are used • Intervention studies: hard to interpret unless properly controlled trials • As yet no convincing evidence from double-blind RCTs that training in auditory processing improves language skills 60
  61. 61. Recommendations • Need for better, well-validated, reliable APD tests with local norms. Reliance on currently-available tests risks over-diagnosis • Complement APD assessment with language, literacy, communication, assessments. What looks like ‘listening problems’ may be high-level comprehension problems • Need for multidisciplinary working 61
  62. 62. 62 Dorothy Bishop Oxford Study of Children’s Communication Impairments, Department of Experimental Psychology, South Parks Road, Oxford, OX1 3UD, England.