ABSTRACT
The current study investigated morphological differences in the corpus callosum in children ages 8 to 18 years old with nonverbal learning disability (NLD; n = 19), high-functioning autism (HFA; n = 23), predominantly inattentive ADHD (ADHD:PI; n = 23), and combined type ADHD (ADHD:C; n = 25), as well as those demonstrating typical development (n = 57). Midsagittal area of the corpus callosum and five midsagittal anterior-to-posterior corpus callosum segments were examined using magnetic resonance imaging. Controlling for midsagittal brain area and age, no group differences were found for total corpus callosum area. This finding indicates that higher functioning children on the autistic spectrum do not have smaller corpus callosi as has been found in previous research with heterogeneous samples. Following segmentation of the corpus callosum, the NLD group was observed to have significantly smaller splenia compared to all other groups. Smaller splenia in the NLD group was associated with lower WASI PIQ scores but not WASI VIQ scores. Children with HFA were observed to have larger midbody areas than children with NLD and neurotypically developing children. Children with HFA and NLD demonstrated behavioral symptoms of inattention and hyperactivity similar to the ADHD groups indicating that corpus callosum differences seen in the NLD and HFA groups are not related to these behaviors.
Subject(s)
Attention Deficit Disorder with Hyperactivity/pathology , Autistic Disorder/pathology , Corpus Callosum/pathology , Learning Disabilities/pathology , Adolescent , Case-Control Studies , Child , Female , Humans , Magnetic Resonance Imaging , Male , Organ SizeABSTRACT
The extant research on nonverbal learning disability (NLD) was analyzed in this review. Studies were defined for use in the review as those that appeared in a peer-reviewed journal and included participants characterized as having NLD. Each study also needed to provide a statistical analysis of dependent variables. An a priori system was used to evaluate the quality of the research. Of the 88 publications found, 32 met criteria for inclusion in the review, with 6 meeting full criteria as strong studies. The diagnostic criteria used and the research findings are briefly discussed, as are proposed guidelines for future research.
