| Objective. To perform a detailed morphometric analysis of the cerebellum in autism with and without macrocephaly.; Method. In Study 1, four subject groups, all males with IQs above 65, 7 to 26 years of age, were studied with quantitative MRI: 28 normocephalic and 13 macrocephalic individuals with autism without mental retardation compared to 16 normocephalic and 8 benign macrocephalic typically developing individuals. Volumes (i.e., gray, white and combined gray and white matter) of the total cerebellum as well as surface areas of four lobular midsagittal groups were measured. In Study 2, two groups were added to these analyses: 5 individuals with autism accompanied by mental retardation and 22 non-autistic individuals with reading disorder.; Results. Independent t-tests between autism and control subjects matched for head size revealed no significant differences. Additionally, multivariate analyses of variance were performed, using diagnostic group as the fixed factor, cerebellar measures as the dependent variables, and total intracranial volume (TICV), total brain volume (TBV), age, verbal IQ (VIQ) and performance IQ (PIQ as covariates. No significant differences were found in any analyses. However, subjects with macrocephaly consistently had slightly smaller findings of cerebellar volume or surface area.; Conclusions. In autism, with and without macrocephaly, cerebellar structures were found to be proportional to head size and did not differ from typically developing or reading disorder subjects. |
