Anterior cingulate gyrus volume and glucose metabolism in autistic disorder.

This study reports the first paired measurements of glucose metabolism and volume of the anterior cingulate gyrus in autism. Magnetic resonance imaging (MRI) and positron emission tomography (PET) scans of seven high-functioning autistic patients and seven sex- and age-matched normal volunteers were coregistered. After the anterior cingulate gyri were outlined on the MRI images, the volumes of the structures were measured and corrected for brain volume. The volumes were then applied to the PET images and metabolic maps were obtained. Right anterior cingulate area 24' was significantly smaller in relative volume, and both area 24 and area 24' were metabolically less active, in the autistic patients than in the normal subjects. Autism may be characterized by structural and functional alterations in the anterior cingulate gyrus.