"It would be invaluable to study larger samples of autistic and control cases at a younger and narrower age range to confirm excess counts in autism at the youngest ages, as well as to study larger samples across a wider age range to identify patterns of age-related changes in autism. It [also] will be important to include female cases in future studies, as etiological mechanisms may be discordant between the sexes," they said.
Future studies with a greater number of subjects also would allow researchers to explore relationships between brain morphology and behavior, possibly revealing whether neuron counts relate to symptom severity or intellectual ability, they added.
This study was supported by Autism Speaks, Cure Autism Now, the Peter Emch Family Foundation, the Simons Foundation, and the Thursday Club Juniors. Also, a grant from the National Institutes of Health–University of California, San Diego Autism Center of Excellence was awarded to Dr. Courchesne and a National Institute of Mental Health grant was awarded to Dr. Courchesne’s associated Dr. Peter R. Moulton. Brain specimens were provided by the National Institute of Child Health and Human Development Brain and Tissue Bank for Developmental Disorders, Autism Tissue Program, and direct donations to the Courchesne laboratory. Dr. Courchesne’s associate, Dr. Michael E. Calhoun, is the principal owner of Sinq Systems, a contract research organization that performed data collection and analysis for this study and he is an applicant on a pending patent on file with the U.S. Patent and Trademark Office related to analysis of microscopic structure.