Current Status of Treatments for Dyslexia: Critical Review

Ann W. Alexander, MD; Anne-Marie Slinger-Constant, MD

Disclosures

J Child Neurol. 2004;19(10):744-758. 

In This Article

Treatments Targeting Auditory Processing

Intervention studies exploring auditory temporal processing deficits in children with reading problems and the impact of interventions designed to remediate these low-level perceptual processing deficits reported in some subsets of subjects with dyslexia have yielded interesting findings.[4,48–50] There are few methodologically sound research studies on the efficacy of these nonlinguistic intervention strategies. Earobics[20] and FastForWord[21] were used in some of the studies reviewed above. These programs are conducted using commercially developed computer programs to address the auditory processing deficit found in a subset of subjects with dyslexia. They use acoustically modified speech to remediate the auditory processing deficit but also tap phonologic skills. FastForWord was developed based on scientific evidence of the relationship between auditory processing and language.[48] It is presented through the auditory channel but also trains syntactic and semantic comprehension. Earobics incorporates graphemes and written words into the program.

Hayes et al. studied 27 children aged 8 to 12 years old with learning impairments (as defined by a discrepancy of at least 1 SD or more between measures of mental ability and reading, spelling, phonologic awareness, or auditory processing).[51] The subjects, who received 8 weeks of auditory perceptual training with Earobics Step I and Step II, exhibited improvements in auditory processing skills and altered cortical responses to speech syllables, with a more mature pattern in quiet and increased resistance to degradation in background noise compared with normal controls and an untreated learning-disabled group. However, these changes did not result in improvement in performance on measures of reading and spelling ability. The possible implications of these results for children with dyslexia are unclear because the subjects included children with attention deficit alone.

Agnew and colleagues studied the impact of a language remediation program using acoustically modified speech (FastForWord), designed to improve auditory temporal processing and language skills.[52] Their primary aim was to assess its effect on the accuracy with which seven children (being seen in a private clinic for FastForWord treatment based on parental concern, clinician referral, or poor school performance) could judge relative durations of auditory and visual stimuli. Their second aim was to ascertain its effect on phonologic decoding. Following 4 to 6 weeks of intensive daily intervention, the subjects demonstrated improvements in the auditory, but not visual, modality on duration judgment tasks. This was interpreted as evidence that the program indeed improved auditory processing and that gains were not due to improved attention. This improvement in auditory temporal discrimination was not associated with improvement in phonologic awareness or nonword reading, results that Agnew and colleagues interpreted as "illustrating the need for further research to establish the relationship between reading and auditory temporal processing." They proposed that the auditory temporal processing difficulty that children with specific language impairment and dyslexia exhibit is the result of poor phonologic representations rather than an auditory temporal processing deficit or, as has been suggested by other researchers, a generalized nervous system deficit in the processing and integration of rapidly successive and transient signals.

In the study described above by Pokorni et al, Earobics Step II and FastForWord were compared with the Lindamood Phoneme Sequencing program.[19] After approximately 60 hours of daily intervention delivered in a small-group setting, reading gains were not noted in either group. Children exposed to Lindamood Phoneme Sequencing were significantly better in improving phonologic awareness with gains in segmenting and blending, and the Earobics group also showed significant gains attributed to phonemic segmentation. No significant gains were found in the FastForWord group.

Temple and colleagues compared the cortical activation patterns of 20 children with dyslexia before and after 8 weeks of FastForWord remediation.[53] Left temporoparietal cortex and left inferior frontal gyrus activation increased following the intervention. In contrast to other studies,[19,52] Temple and colleagues demonstrated group improvement in both oral language and reading performance in association with these changes in cortical activity. Their subjects were moderately impaired in nonword reading (standard score 85.5, SD 7.9), average in oral language (receptive language standard score 92.5, SD 12.1), and severely impaired in rapid naming (standard score 79.1, SD 14.5). Significant gains were found in nonword reading, word identification and passage comprehension, receptive and expressive language, and rapid naming. Only nonword reading reached the 30th percentile benchmark, with a post-treatment score of 93.7 (range 82–109). Oral language already exceeded it before treatment. However, there were no significant gains in oral language for 10 (50%) of the subjects. Similarly, there were no significant reading gains for 9 (45%) of the subjects. Similar data for rapid naming are not reported. The amount of activation in the left temporoparietal area correlated with improvement in oral language ability. Increased activity in the right hemisphere frontal and temporal regions, as well as the bilateral anterior cingulate, was noted. Temple et al. suggested that the cingulate might represent improved attention and that the homotopic right hemisphere areas might represent compensatory activity, which might decrease with improved function.

Whereas gains in auditory, phonologic, and language processing have been noted with these programs, the gains in reading skills have been, at best, inconsistent and have not matched the gains in reading reported by programs using systematic phonologic awareness and phonics interventions. Both programs have developed new software that includes phonics and language instruction. The efficacy of these additions has yet to be reported.

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