Volumetric Alterations in Brain Structures Caused by Autism during Different Age Stages

Conclusions in literature regarding the effect of Autism on the size of different brain structures are contradictory. The aim of this study is to determine the effect of Autism on the volumes of different brain subcortical structures, and the age stage at which those changes occur. 7 main brain structures were segmented, and their volumes were obtained. Volumes and the ratio of the volume to total brain volume (SBR) were compared in Autism group to their corresponding values in Control group. Then, each group was divided into 4 subgroups based on age; the comparison was repeated for each subgroup. Independent t-test was used to determine if significant differences existed between compared groups. Significant reductions were observed in the SBR of Autistic Pallidum and Accumbens compared to Control group when considering the full range of ages (5-25 years). However, Amygdala's volume was significantly smaller in Autism in the 5-8 year subgroup. In addition, the SBR of Putaman, Pallidum, Hippocampus, and Accumbens were reduced in the 18-25 year Autism subgroup. In conclusion, the alteration in the ratio of structure's volume to total brain volume is a better indicator of Autism diagnosis than change in the absolute volume alone.