Objective: To examine prefrontal and occipital asymmetry (brain torque) in boys with autism spectrum disorder (ASD) and controls. A secondary aim was to study age-related changes in gray and white matter volume.
Background: Several studies have found atypical early cortical development in ASD. Atypical brain torque, defined as a greater-than-normal left prefrontal and right occipital asymmetry, has been found in some studies of children and adults with ASD. This configuration may be an early neural marker of ASD risk.
Methods: We studied 24 right-handed boys with ASD and 27 typically developing right-handed boys, 7 to 15 years old, obtaining neuropsychological profiles and measuring prefrontal and occipital volumes on magnetic resonance images.
Results: Most participants had the expected rightward prefrontal and leftward occipital asymmetry, with no group differences in direction or degree of asymmetry. We found a trend toward larger prefrontal volume in the ASD group than in the controls. The controls also had a trend toward differences in age associations, correlating with total and left prefrontal white matter volumes.
Conclusions: Our findings suggest that atypical brain torque may not be a neural signature of ASD, although our sample was limited to high-functioning, right-handed boys. Our results provide support for aberrant cortical development in ASD, continuing into adolescence, with prefrontal regions being disproportionally affected.
*Brain and Behavior Program at Children’s Hospital
Departments of †Neurology
§Cell Biology and Anatomy, Louisiana State University Health Sciences Center, New Orleans, LA
‡Department of Psychology, Boston University, Boston, MA
Supported by Program Project Grant U19 DC 03610 from the National Institute on Deafness and Other Communication Disorders (NICHD/NIDCD-funded Collaborative Programs on Excellence in Autism) and the NIH-funded General Clinical Research Center at Boston University School of Medicine (M01-RR0533).
The authors declare no conflicts of interest.
Reprints: Anne L. Foundas, MD, Brain and Behavior Program at Children's Hospital, 935 Calhoun Street, New Orleans, LA 70118 (e-mail: firstname.lastname@example.org).
Received October 7, 2011
Accepted August 8, 2012