Impaired non-speech auditory processing at a pre-reading age is a risk-factor for dyslexia but not a predictor: an ERP study.

Impaired auditory sensitivity to amplitude rise time (ART) has been suggested to be a primary deficit in developmental dyslexia. The present study investigates whether impaired ART-sensitivity at a pre-reading age precedes and predicts later emerging reading problems in a sample of Dutch children. An oddball paradigm, with a deviant that differed from the standard stimulus in ART, was administered to 41-month-old children (30 genetically at-risk for developmental dyslexia and 14 controls) with concurrent EEG measurement. A second deviant that differed from the standard stimulus in frequency served as a control deviant. Grade two reading scores were used to divide the at-risks in a typical-reading and a dyslexic subgroup. We found that both ART- and frequency processing were related to later reading skill. We however also found that irrespective of reading level, the at-risks in general showed impaired basic auditory processing when compared to controls and that it was impossible to discriminate between the at-risk groups on basis of both auditory measures. A relatively higher quality of early expressive syntactic skills in the typical-reading at-risk group might indicate a protective factor against negative effects of impaired auditory processing on reading development. Based on these results we argue that ART- and frequency-processing measures, although they are related to reading skill, lack the power to be considered single-cause predictors of developmental dyslexia. More likely, they are genetically driven risk factors that may add to cumulative effects on processes that are critical for learning to read.