Neural correlates of communication skill and symptom severity in autism: A voxel-based morphometry study

Abstract

Although many studies have compared the brains of normal controls and individuals with autism, especially older, higher-functioning individuals with autism, little is known of the neural correlates of the vast clinical heterogeneity characteristic of the disorder. In this study, we used voxel-based morphometry (VBM) to examine gray matter correlates of variation in communication skill and symptom severity within a heterogeneous group of 33 children with autism ranging in age from 3.4 to 11.4 years. Greater gray matter (GM) volume was associated with better communication skills in numerous frontal regions, especially in the left middle frontal gyrus. Further, greater GM volume in the right inferior frontal gyrus was associated with reduced severity of symptoms of autism. However, increased total GM volume was correlated with more severe symptoms of autism at a trend level, consistent with other studies, suggesting that while increased total GM volume is generally predictive of greater autistic severity, specific local increases in GM volume result in a reduction in symptoms. Our results suggest that communication and symptom severity have distinct neuroanatomic correlates and draw attention to the importance of studying the neuroanatomy of clinical heterogeneity within the autistic population.