Same or Different: The Overlap Between Children With Auditory Processing Disorders and Children With Other Developmental Disorders: A Systematic Review
Authors: de Wit Ellen , van Dijk Pim , Hanekamp Sandra , Visser-Bochane Margot I. , Steenbergen Bert , van der Schans Cees P. , Luinge Margreet R. 
Published: September 2017

Objectives:
Children diagnosed with auditory processing disorders (APD) experience difficulties in auditory functioning and with memory, attention, language, and reading tasks. However, it is not clear whether the behavioral characteristics of these children are distinctive from the behavioral characteristics of children diagnosed with a different developmental disorder, such as specific language impairment (SLI), dyslexia, attention-deficit hyperactivity disorder (ADHD), learning disorder (LD), or autism spectrum disorder. This study describes the performance of children diagnosed with APD, SLI, dyslexia, ADHD, and LD to different outcome measurements. The aim of this study was to determine (1) which characteristics of APD overlap with the characteristics of children with SLI, dyslexia, ADHD, LD, or autism spectrum disorder; and (2) if there are characteristics that distinguish children diagnosed with APD from children diagnosed with other developmental disorders.

Design:
A systematic review. Six electronic databases (Pubmed, CINAHL, Eric, PsychINFO, Communication & Mass Media Complete, and EMBASE) were searched to find peer-reviewed studies from 1954 to May 2015. The authors included studies reporting behaviors and performance of children with (suspected) APD and children diagnosed with a different developmental disorder (SLI, Dyslexia, ADHD, and LD). Two researchers identified and screened the studies independently. Methodological quality of the included studies was assessed with the American Speech-Language-Hearing Association’s levels-of-evidence scheme.

Results:
In total, 13 studies of which the methodological quality was moderate were included in this systematic review. In five studies, the performance of children diagnosed with APD was compared with the performance of children diagnosed with SLI: in two with children diagnosed with dyslexia, one with children diagnosed with ADHD, and in another one with children diagnosed with LD. Ten of the studies included children who met the criteria for more than one diagnosis. In four studies, there was a comparison made between the performances of children with comorbid disorders. There were no studies found in which the performance of children diagnosed with APD was compared with the performance of children diagnosed with autism spectrum disorder. Children diagnosed with APD broadly share the same characteristics as children diagnosed with other developmental disorders, with only minor differences between them. Differences were determined with the auditory and visual Duration Pattern Test, the Children’s Auditory Processing Performance Scale questionnaire, and the subtests of the Listening in Spatialized Noise-Sentences test, in which noise is spatially separated from target sentences. However, these differences are not consistent between studies and are not found in comparison to all groups of children with other developmental disorders.

Conclusions:
Children diagnosed with APD perform equally to children diagnosed with SLI, dyslexia, ADHD, and LD on tests of intelligence, memory or attention, and language tests. Only small differences between groups were found for sensory and perceptual functioning tasks (auditory and visual). In addition, children diagnosed with dyslexia performed poorer in reading tasks compared with children diagnosed with APD. The result is possibly confounded by poor quality of the research studies and the low quality of the used outcome measures. More research with higher scientific rigor is required to better understand the differences and similarities in children with various neurodevelopmental disorders.