Nonverbal Learning Disability (NVLD) is a syndrome characterized by impaired social perception, visual-spatial skills, fine motor coordination, and mathematics abilities. Researchers have found that children with NVLD often have significant symptoms of inattention, and there is evidence that the majority of children with NVLD also meet clinical criteria for Attention Deficit/Hyperactivity Disorder, Predominantly Inattentive Subtype (ADHD:PI) (Brown, 2000; Gross-Tsur & Shalev, 1995; Voeller, 1996). Although significant overlap is observed between NVLD and behavioral symptoms of ADHD, little research has focused on the specific attention problems of children with NVLD.
Given the high incidence of co-morbid attention problems with NVLD (Brown, 2000), many researchers have proposed that overlapping neural regions are responsible for the similarity in attention impairments observed in both NVLD and ADHD:PI (Denckla, 2000; Stefanatos, 2001). Other researchers suggest that there are distinct neurological impairments in children with NVLD and both subtypes of ADHD that result in attention problems. Specifically, Rourke (1995) suggested a developmental sequence that results in generally intact auditory attention with impaired attention for visual stimuli in children with NVLD.
This study sought to reconcile the discrepancy between conceptualizations of attention problems in children with NVLD. It was hypothesized that children with NVLD would exhibit distinct profiles of strengths and weaknesses on neuropsychological measures of attention compared to children with ADHD, Predominantly Inattentive Subtype (ADHD:PI) and ADHD, Combined Subtype (ADHD:C). Specifically, it was expected that the three diagnostic groups would differ on the neuropsychological measures depending on the attention modality (auditory vs. visual).
Extant neuropsychological data from 88 children between the ages of 9 and 15 years of age with diagnoses of NVLD, ADHD:PI, and ADHD:C were analyzed. Neuropsychological measures of processing speed, working memory, vigilance, and inhibition were examined to compare specific domains of attention functioning in the three groups. Evidence from the current study supported the model in which NVLD and the two ADHD subtypes represent a continuum of dysfunction dependant on overlapping neural regions. Moreover, specific attention strengths and weaknesses in children with NVLD compared to children with ADHD:PI, ADHD:C, and normative data were identified in order to inform clinical diagnosis and intervention.