The role of central auditory processing in attention-deficit/hyperactivity disorder : a neuropsychological investigation

Central Auditory Processing Disorder (CAPD) is defined as a modality-specific perceptual dysfunction that is not due to peripheral hearing impairment (McFarland & Candace, 1995). It may include limitations in the ongoing transmission, analysis, transformation, elaboration, storage, retrieval and use of auditory stimuli. CAPD has also been reported to be associated with difficulties in memory, reading, spelling, language, and attention. The broad conceptualization of CAPD has contributed to difficulty in the diagnosis and treatment of children who present with auditory processing impairment. A major concern related to the lack of specificity in the definition of CAPD is the inclusion of attention. The clinical overlap in CAPD and ADHD has led to research questions regarding the validity of CAPD as a distinct disorder. Participants were 30 children aged eight to 14 re-recruited from a larger study investigating social competence in ADHD. They were asked to volunteer to complete additional measures of attention and auditory processing. Prior to participating they had completed the Behavioral Assessment System for Children- Parent Rating Scale (BASCPRS) and the SIDAC. The BASC was used as measure of externalizing behavior and the SIDAC was used to classify participants into subtypes of ADHD. Participants completed the SCAN (Keith, 1995) as a measure of auditory processing and the Tests of Variables of Attention- Auditory (T.O.V.A.-A.) as a measure of attention. Participants were placed into groups based on their subtype of ADHD. There were two groups including ADHD/PI and a collapsed group including ADHD/combined and ADHD/HI. Discriminant function analysis was used to determine the accuracy of classification into subtypes using combinations of the predictor variables. Results of the analyses indicated that externalizing behavior was the most robust predictor variable, with an accuracy rate of 80 percent. Including auditory processing and auditory attention did not improve the classification rate. When used alone as a predictor variable, auditory processing was not found to not be effective in classifying participants. Results have research and clinical implications. Sensitivity and specificity issues related to the measures used are discussed. Recommendations for future research are offered.