Rate of Head Circumference Growth as a Function of Autism Diagnosis and History of Autistic Regression

Abstract

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...

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

“…One head circumference study of 28 males with autism (11 with regression) did not report an association between onset status and rate of head growth in the first year of life (19). It is likely that the substantially larger sample size and retrospective longitudinal data in the present study provided greater statistical power to detect differences in the pattern of head growth.…”

“…Although there are a number of complexities in determining onset status (18), children with autism can be characterized as regression (REG) or no regression (nREG), using parent report of early development. The neural underpinnings of onset status remain unclear because only one study has yet examined this question, in a small sample (19).…”

Atypical functional lateralization of language in autism spectrum disorders

“…As such, the atypical functional organization of language found in the current study may be due to the aberrant neurodevelopmental processes which have been recently identified in ASD. Recent studies demonstrated that rapid, excessive brain growth occurs in the first years of life in autism (Courchesne et al, 2003;Dementieva et al, 2005;Webb et al, 2007). In the Courchesne et al study, head circumference measures showed that autistic newborns were in the 25th percentile for head size at birth, which was significantly smaller than the normative sample.…”

Selective Attention and Perceptual Load in Autism Spectrum Disorder

“…In a recent longitudinal study, Webb and colleagues examined the rate of head circumference growth (extracted from medical records) of a group of boys with ASD and a group with developmental delay over the first three years of life (Webb et al, 2007). They found that there was a significantly higher rate of growth in the ASD group -more specifically, a statistically significant increase in occipitofrontal circumference between 7 and 10 months, relative to norms.…”