Brain enlargement is associated with regression in preschool-age boys with autism spectrum disorders

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 108; no. 50; pp. 20195 - 20200
• Main Authors: Nordahl, Christine Wu, Lange, Nicholas, Li, Deana D, Barnett, Lou Ann, Lee, Aaron, Buonocore, Michael H, Simon, Tony J, Rogers, Sally, Ozonoff, Sally, Amaral, David G
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 13.12.2011; National Acad Sciences
• Subjects: Autism; Autistic disorder; Biological Sciences; boys; Brain; Brain - growth & development; Brain - pathology; Cephalometry; Cerebrum - pathology; Child Development Disorders, Pervasive - pathology; Child growth; Child, Preschool; childhood; Female; Genotype & phenotype; girls; head; Head circumference; Humans; Infant; Infant, Newborn; Male; Measurement; Organ Size; Parents; parturition; Pervasive child development disorders; phenotype; Phenotypes; Regression (Psychology); Regression analysis; Reproduction; risk factors; Sample size; Trajectories
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1107560108

Autism is a heterogeneous disorder with multiple behavioral and biological phenotypes. Accelerated brain growth during early childhood is a well-established biological feature of autism. Onset pattern, i.e., early onset or regressive, is an intensely studied behavioral phenotype of autism. There is currently little known, however, about whether, or how, onset status maps onto the abnormal brain growth. We examined the relationship between total brain volume and onset status in a large sample of 2- to 4-y-old boys and girls with autism spectrum disorder (ASD) [n = 53, no regression (nREG); n = 61, regression (REG)] and a comparison group of age-matched typically developing controls (n = 66). We also examined retrospective head circumference measurements from birth through 18 mo of age. We found that abnormal brain enlargement was most commonly found in boys with regressive autism. Brain size in boys without regression did not differ from controls. Retrospective head circumference measurements indicate that head circumference in boys with regressive autism is normal at birth but diverges from the other groups around 4–6 mo of age. There were no differences in brain size in girls with autism (n = 22, ASD; n = 24, controls). These results suggest that there may be distinct neural phenotypes associated with different onsets of autism. For boys with regressive autism, divergence in brain size occurs well before loss of skills is commonly reported. Thus, rapid head growth may be a risk factor for regressive autism.