19814
The Effect of Demographic and Clinical Features on the Volume of Corpus Callosum in Preschoolers with Autism Spectrum Disorder: A Case-Control Study
A growing body of literature has identified size reduction of the corpus callosum (CC), in subjects with autism spectrum disorders (ASD). The CC volume also appears to be inversely related to autism severity and to intelligence quotient (IQ). However, to date very few studies have been conducted on preschool-age ASD children.
Objectives:
to compare the volume of CC and its sub-regions between preschoolers with ASD and controls subjects (CON) and to examine their relationship to demographic and clinical variables (gender, age, non-verbal IQ –NVIQ-, expressive non-echolalic language, emotional and behavioral problems, and autism severity).
Methods:
CC volume of 40 preschoolers with ASD (20 M and 20 F; mean age: 49 ± 12 months; mean NVIQ: 73 ±22) and 40 gender, age, and NVIQ-matched CON subjects (20 males –M- and 20 females –F-; mean age: 49 ± 14 months; mean NVIQ: 73 ± 23) were quantified with an automated parcellation approach using FreeSurfer software (http://surfer.nmr.mgh.harvard.edu/) on MRI images. Clinical parameters were assessed using standardized tests, such as Leiter International Performance Scale-Revised, or Griffiths Mental Development Scale for intelligence quotient, Autism Diagnostic Observation Schedule-Generic (ADOS-G) for autism severity, consensus group about productive language abilities in ASD children (Tager-Flusberg et al., 2009) for level of expressive non-echolalic language, Child Behaviour CheckList 1½-5 (CBCL 1½-5) for emotional and behavioral problems.
Results:
no significant volumetric differences in CC total volume between ASD and CON were found when Total Brain Volume (TBV) was used as a covariate (p=0.15). Analogously, absence of CC volumetric differences was evident when boys and girls with ASD were compared to their matched controls (M: p=0.57; F: p=0.53). By further subdividing the CC into five anatomically discrete portions (anterior, mid-anterior, central, mid-posterior and posterior), no statistically significant differences in volumes of CC subregions between ASD patients and CON were detected, considering TBV as covariate. CC total volume was positively correlated with age in CON (p=0.009), but not in ASD subjects. Moreover, CC total volume were negatively correlated with ADOS-G total score (p= 0.018), and with ADOS-G Language and Communication-subscores (p=0.017), whereas no association between CC volume and other variables (NVIQ, language, emotional and behavioral problems) was detected.
Conclusions: In agreement with some, but not all, of the studies on CC volume in ASD subjects, we didn’t find CC volumetric differences between ASD preschoolers and carefully matched controls. The absence of positive correlation between CC volume and age in ASD patients confirms the atypical growth trajectory widely reported in these young children, whereas the indirect relationship between CC volume and ADOS-G scores suggests the involvement of the CC in core ASD symptoms.