Background-Longitudinal studies of head circumference growth in infants later diagnosed with autism are needed to understand the accelerated head growth in this disorder.

Several reports indicate that autism spectrum disorder (ASD) is associated with increased rate of head growth in early childhood. Increased rate of growth may index aberrant processes during early development, may precede the onset of symptoms, and may predict severity of the disease course. We examined rate of change in occipitofrontal circumference measurements (abstracted from medical records) in 28 boys with ASD and in 8 boys with developmental delay without autism from birth to age 36 months. Only children who had more than 3 occipitofrontal circumference measurements available during this age period were included. All data were converted to z scores based on the Centers for Disease Control and Prevention norms. Rate of growth from birth to age 36 months was statistically significantly higher for the ASD group than the developmental delay group, with children with ASD showing a statistically significant increase in occipitofrontal circumference relative to norms between 7 and 10 months; this group difference in rate of growth was more robust when height was used as a covariate. Rate of growth was not found to be different for children with ASD whose parents reported a history of loss of skills (regression) vs those whose parents reported early onset of autism symptoms. Findings from this study suggest that the aberrant growth is present in the first year of life and precedes the onset of diagnosis in children with ASD with and without a history of autistic regression. Keywords autism; head circumference; growth Autism spectrum disorder (ASD) is a category of neurodevelopmental disorders characterized by impairments in social relationships and communication and by the presence of repetitive interests and stereotyped behaviors. Basic impairments, such as lack of attention to others and failure to orient to name, often appear within the first year of life. 1 Using retrospective investigations, other subtle impairments in the domains of motor, sensory perception, attention, and social behaviors are present in the first year. 1,2 In a study of high-risk infants, Zwaigenbaum et al 3 found that by 12 months of age infants who later were diagnosed as having ASD differed from nonrisk infants in terms of their eye contact, failure to orient to name, impoverished social interest and affect, atypical visual attention and temperament, and delayed language development. By preschool age, behavioral symptoms of ASD include impairments Address correspondence to: Sara Jane Webb, PhD, Center on Human Development and Disability, University of Washington, Campus Box 357920, CHDD 314, Seattle WA 98195; sjwebb@u.washington.edu. This research was conducted at the University of Washington, Seattle. in social orienting, eye contact, joint attention, imitation, responses to the emotional displays of others, and face recognition. [4][5][6][7][8] Although the social behavior of individuals with ASD has been well characterized, the basic neurobiological mechanisms underlying these impairments are poorly understood. NIH Public Ac...

OBJECTIVE. This retrospective study explored sensory processing characteristics in preschool-age children with autism spectrum disorders (ASD); the relationships between sensory processing and problem behavior, adaptive behavior, and cognitive function; and the differences in sensory processing between two subgroups (autism and pervasive developmental disorder-not otherwise specified). RESULTS. Most of the children with ASD had sensory processing challenges, and a significant relationship was found between SSP total scores and problem behavior scores; however, no significant relationships were found between SSP total scores and adaptive behavior and cognitive functioning. Although all the children had low Vineland scores, approximately one-quarter of the children had typical SSP scores. No significant differences in SSP scores were found between the subgroups. METHOD. Study measures included theCONCLUSION. The findings highlight the importance of comprehensive evaluations for children with ASD.