AN MRI STUDY OF AUTISM - THE CEREBELLUM REVISITED

We addressed the controversies surrounding the size of the neocerebell ar vermis in autism and examined cerebellar size in light of recent re ports of enlarged brain size in this disorder. In this study we use de tailed MRI (1.5 mm) to examine the area of cerebellar lobules I throug h V and VI and VII and the volume of the total cerebellum in 35 autist ic subjects and 36 controls. No abnormalities in the size of cerebella r lobules VI and VII in autistic individuals were detected, but the vo lume of the total cerebellum was significantly increased. We conclude that selective neocerebellar size abnormalities are not present in aut istic individuals. Enlarged total cerebellar volume detected in this s tudy is consistent with previous reports of regional brain enlargement in autism and also consistent with theories hypothesizing that the pr imary defect in autism is the result of abnormal development of a dist ributed neural network involving a number of regions of the brain.