Russo et al. (2008)

NATURE OF PROSODIC DISORDERS

ANALYSIS FORM

 

Key:

 

ASD = Autism spectrum disorders

fo = fundamental frequency

H2 = second harmonic

NA = not applicable

P = participant or patient

pmh = Patricia Hargrove, blog developer

TD = typically developing

WNL = within normal limits

 

 

SOURCE:  Russo. N. M., E. Skoe, E., Trommer, B., Nicol, T., Zecker, S., Bradlow, N., Kraus, N. (2008). Deficient brainstem encoding of pitch in children with Autism Spectrum Disorders. Clinical Neurophysiology, 119, 1730-1731.

 

REVIEWER(S): pmh

 

DATE: June 21, 2015

ASSIGNED GRADE FOR OVERALL QUALITY: B+ (The highest grade for this investigation, based on its design, is B+.)

 

POPULATION: Autism Spectrum Disorders (ASD)

 

PURPOSE: To investigate the subcortical responsiveness to prosody in children with ASD.

 

INSIGHTS ABOUT PROSODY:

  • The ability of children with ASD to encode pitch less was accurate/preserved and less robust than typically developing (TD) peers.
  • However, subgroup analysis of the ASD group revealed that a small group of children with ASD (i.e., ASD OUT) accounted for the poor pitch encoding scores.
  • The ASD OUT group included 5 Ps (about 20% of the overall ASD group) and they exhibited more Frequency and Slope errors as well as reduced pitch locking.

 

 

  1. What type of evidence was identified? Prospective, Nonrandomized Group Comparison Design
  1. Group membership determination:

 

  • If there were groups of participants were members of groups matched? Yes

                                                                    

  • The participants (Ps) were matched by age.
  1. Was participants’ communication status concealed?

                                                                                                           

  • from participants? No
  • from assessment administrators? No
  • from data analyzers? Unclear

                                                                    

 

  1. Were the groups adequately described? Yes

– How many participants were involved in the study?

  • total # of participants: originally there were 48 Ps but 6 Ps with ASD were eliminated due to abnormal brainstem responses (click evoked brainstem responses –atypical Wave V latency), noncompliance, parental choice, and/or relocation; the working total of Ps was 42
  • was group membership maintained throughout the experiment? 6 Ps withdrew/were eliminated from the investigation, as noted above
  • # of groups: 2
  • List names of groups: Autism Spectrum Disorders (ASD), typically developing (TD)
  • # of participants in each group: ASD = 21; TD = 21

                                                                                

– Characteristics of Ps:

CONTROLLED                                                                                           

  • age: 7 to 13 years
  • cognitive skills: Full scale IQ In which with the confidence intervals, the value is >80
  • hearing: within normal limits (WNL)
  • diagnosis: for the Ps with ASD, diagnosis by neurologist/psychologist and actively followed
  • neurological problems: lack of confounding neurological problems

 

DESCRIBED

  • age: mean age ASD = 9.9; mean age TD = 9.95 (no significant difference)
  • gender: ASD = 19m, 2f; TD = 13m, 8f
  • cognitive skills: for both groups the mean was WNL, although TD Ps scored significantly higher
  • expressive language: mean scores on the core portion of the Clinical Evaluation of Language Fundamentals were WNL, although TD Ps scored significantly higher
  • receptive language: mean scores on the receptive portion of the Clinical Evaluation of Language Fundamentals were WNL, although TD Ps scored significantly higher
  • overall language skills: mean scores of the core Clinical Evaluation of Language Fundamentals were WNL, although TD Ps scored significantly higher
  • diagnoses of Ps with ASD: parent reported the following specific diagnoses– autism, Asperger Disorder, PDD-NOS, combined diagnoses
  • supplemental observations by investigators of Ps with ASD: Ps displayed some or all of the following

   – limited eye contact

   – limited reciprocity

   – restricting range of topics in conversation

   – use of restricted or idiosyncratic language

   – abnormal prosody

   – echolalia or scripted speech

   – stereotyped movements

 

Were the communication problems adequately described? Yes, but I would have liked to see a description of the communication scores of ASD OUT versus ASD IN Ps.

  • disorder type: ASD
  • functional level: observations by investigators of Ps with ASD revealed that Ps displayed some or all of the following:

– limited eye contact

– limited reciprocity

– restricting range of topics in conversation

– use of restricted or idiosyncratic language

– abnormal prosody

– echolalia or scripted speech

 

  1. What were the different conditions for this research?
  • Subject (Classification) Groups? Yes: ASD, TD
  • Experimental Conditions? No
  • Criterion/Descriptive Conditions? Yes: passively evoked brainstem responses to

     – click evoked brainstem responses

     – speech evoked brainstem responses– speech syllables with descending and ascending pitch contours

  1. Were the groups controlled acceptably? Yes

 

 

  1. Were dependent measures appropriate and meaningful? Yes

– The dependent measures were

  • Dependent Measure #1: Wave V latency within the normal range (this was actually an exclusionary criterion; 2 Ps with ASD were excluded from the original 48 Ps)
  • Dependent Measure #2: Rate of frequency errors (an accuracy measure of encoding) for fo (fundamental frequency) and H2 (second harmonic)
  • Dependent Measure #3: Rate of slope error (a measure of preservation of the pitch contour) for fo (fundamental frequency) and H2 (second harmonic)
  • Dependent Measure #4: Rate of pitch strength (a measure of periodicity) for fo (fundamental frequency)
  • Dependent Measure #5: Composite score of overall pitch tracking (frequency errors of fo plus frequency errors and pitch strength of H2)
  • Dependent Measure #6: Relationship of age, sex, and intelligence on brainstem responses

None of the dependent measures that were subjective.

 

– All of the dependent/ outcome measures were objective.

                                         

 

  1. Were reliability measures provided?

                                                                                                            

  • Interobserver for analyzers? No
  • Intraobserver for analyzers? No
  • Treatment/Procedural fidelity for investigators? No
  • Test/Retest Reliability? Yes. Six Ps with ASD were retested. There were no significant differences in the first and second administrations of the protocol using nonparametric statistical analysis. Accordingly, the Ps responses were judged to be stable and reliable.

 

 

  1. Brief description of design:
  • The investigators compared Ps with ASD and TD peers on series of measures representing the subcortical processing of prosody using passively evoked brainstem responses.
  • Ps watched a video of their choice as the experimental stimuli were delivered to the right ear. The investigators instructed the Ps to ignore the sounds in their right ear.
  • Two sets of stimuli were presented:

– clicks (these were part of the exclusion criteria. Ps with abnormal Wave V latency were excluded from the investigation)

– speech (a single syllable [ya] with ascending and descending pitch contours)

  • The investigators compared the TD and ASD groups on the dependent measures using parametric statistics.
  • They then performed follow up with an statistical analysis of the ASD group (using nonparametrics) in which they identified two subgroups: ASD OUT and ASD IN.

 

 

  1. What were the results of the inferential statistical testing

 

– The comparisons that are significant are p ≤ 0.05.

NOTE: For several of the dependent measure, there were 2 sets of comparisons:

  • ASD vs TD and
  • a subgroup analysis for the ASD Ps — ASD OUT (n = 5) vs ASD IN (n = 16.)

The subgroups of ASD were classified on the basis of performance on the composite score (Dependent measure #5.) The ASD OUT group (i.e., deficient pitch trackers) had composite scores that were <1.65 standard deviations from the overall ASD mean composite score. The ASD OUT group comprised

– 3 Ps with Asperger Disorder

– 1 P with PDD-NOS

– 1 P with ASD with Sensory Integration Disorder

  • Dependent Measure #1: Wave V latency within the normal range (this was actually an exclusionary criterion)— no significant differences between ASD and TD groups, although 2 Ps with were eliminated from the investigation;

 

  • Dependent Measure #2: Rate of frequency errors (an accuracy measure of encoding) for fo (fundamental frequency) and H2 (second harmonic)

For fo, the overall ASD group was significantly less accurate than the TD group.

     — For H2, the overall ASD group was significantly less accurate than the TD group.

   — Reanalysis of the data with the ASD subgroups revealed that for fo and for H2, the ASD IN performed similarly to the TD group but that the ASD OUT group differed significantly more poorly than the TD group and the ASD IN subgroup.

 

  • Dependent Measure #3: Rate of slope error (a measure of preservation of the pitch contour) for fo (fundamental frequency) and H2 (second harmonic)

— For fo, no significant differences between ASD and TD groups.

   — For H2, no significant differences between ASD and TD groups.

  • Dependent Measure #4: Rate of pitch strength (a measure of periodicity) for fo (fundamental frequency)

For fo, the ASD group yielded significantly higher scores than the TD group.

   — Reanalysis of the data with the ASD subgroups revealed that for fo, the ASD IN performed similarly to the TD group but that the ASD OUT group differed significantly from TD and the ASD IN subgroup.

  • Dependent Measure #5: Composite score of overall pitch tracking (frequency errors of fo plus frequency errors and pitch strength of H2)

— Overall, the TD group was significantly better than the ASD group.

 

  • Dependent Measure #6: Relationship of age, sex, and intelligence on brainstem responses

— Overall, Ps in the ASD group had significantly poorer scores than the TD group on measures of language skills (CELF) and most measures of intelligence with the exception of performance mental skills.

     — For the ASD subgroups, there were no significant differences on the measures of language and intelligence.

– What were the statistical tests used to determine significance? MANOVA, Mann-Whitney U, Kruskal-Wallis, and Chi square.

– Were effect sizes provided? Yes, but only for some of the measures. If an effect size is not listed for a dependent measure, it was not provided in the paper.

  • Dependent Measure #2: Rate of frequency errors (an accuracy measure of encoding) for fo (fundamental frequency) and H2 (second harmonic)

— For fo, the effect size for ASD vs TD scores was d = 0.61 (moderate)

     — For H2, the effect size for ASD vs TD scores was d = 0.73 (moderate)

  • Dependent Measure #4: Rate of pitch strength (a measure of periodicity) for fo (fundamental frequency)

— For fo, the effect size for ASD vs TD scores was d = 0.56 (moderate)

  • Dependent Measure #5: Composite score of overall pitch tracking (frequency errors of fo plus frequency errors and pitch strength of H2)

– Were confidence interval (CI) provided? No

 

 

  1. What were the results of the correlational statistical testing?
  • Dependent Measure #6: Relationship of age, sex, and intelligence on brainstem responses

– For the overall ASD group and the ASD IN subgroup, significant differences were not noted for the following

  • pitch tracking and measures of intelligence
  • pitch tracking and language measures (CELF)

     – Correlational analysis could not be performed with the data for the ASD OUT subgroup due to the small n.

  • What was the statistical test used to determine correlation? Pearson Product
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