Neuroimaging in developmental disorders

This review considers the role of neuroimaging in developmental disorders by highlighting recent studies in two distinct, but overlapping, developmental disorders: autism and fragile X syndrome.

After a decade of conflicting results in neuroimaging studies of autism, recent studies have provided some convergent data. One well-replicated finding is that autistic subjects have larger brains. Further, this enlargement, present as early as 3 years of age, appears to represent accelerated growth in infancy and may be followed by slowed growth in late childhood. Other findings are discussed but considered preliminary in the absence of converging evidence or replication studies. Recent work in fragile X syndrome suggests aberrant fronto-striatal and fronto-parietal networks and relates these abnormalities "forward" to behavior and "backward" to decreased protein expression.

As the field of neuroimaging has matured, it has revealed its promise as a safe, reliable, in-vivo tool in the study of developmental disorders. By insisting on larger, more homogeneous patient groups and longitudinal rather than cross-sectional studies, the field is poised to fulfill its ultimate role of linking defects in molecular biology to aberrant behavior.