Differences in Physical Characteristics between Children with Autism and Children with Other

Developmental Disorders

Bhavan A. Modi, Dr. Sarah O’Kelley,

Eva Trinh, and Kristi C. Guest

The University of Alabama at Birmingham

Abstract• There have been mixed findings related to physical characteristics (head

circumference, height, and weight) in children with an autism spectrum disorder. Courchesne et. al (2003) found a larger head circumference in children with autistic disorder compared to children with Asperger’s or PDD-NOS. However, Chawarska et. al (2011) found no difference in head circumference between the autism group and the PDD-NOS group. The current study proposed 2 hypotheses: (1) children with ASD will be larger in all 3 aspects when compared to children with other developmental disorders (Other DD) and (2) children with higher autism symptom severity will have a larger head circumference percentile. The current sample included 201 children who were referred to UAB Sparks Clinic for an ASD evaluation. Data was collected from interdisciplinary clinical reports. Based on final diagnosis, each child was included in the ASD group (mean age = 60.7 months ; SD = 30.5; mean BMI = 20.2) or the Other DD group (mean age = 47.3 months ; SD = 23.7; mean BMI = 22.4). No differences were found between the two groups, and no correlation was found between head circumference percentile and ADOS severity. Physical characteristics can perhaps provide a better phenotype of children with an ASD.

Introduction• Autism Spectrum Disorder, along

with its known neurodevelopmental symptoms, has been associated with physical characteristics including head circumference, height, and weight.• However, mixed findings have been

reported.

Background

• Courchesne et. al (2003) found that at birth children with autism had a smaller head circumference compared to the Center of Disease Control and Prevention averages. However, by 6-14 months of age, head circumference increased significantly. In addition, children with autistic disorder had a larger head circumference than children with PDD-NOS.

Background

• In contrast to what Courchesne et. al found, Torrey et. al (2004) found no difference in head circumference at birth between children with autism and children without autism. However, at 12 months of age, 4 years of age, and 7 years of age, children with autism had a slightly larger head circumference, were slightly heavier, and slightly taller than children without autism.

Background

• Chawarska et. al (2011) compared 4 different groups including children with autism, children with PDD-NOS, children with global developmental delay, and children who were typically developing. There were no differences amongst any of the groups. However, the researchers found that children who were in the top 10% of overall physical size had a higher social deficit and lower adaptive functioning.

Hypotheses1. Children with ASD will be larger in all 3

aspects (head circumference percentile, weight percentile, and height percentile) when compared to children with other developmental disorders (Other DD).

2. Children with higher autism symptom severity will have a larger head circumference percentile.

Methods• Children were referred to UAB Civitan Sparks Clinic for an

ASD evaluation. • Anthropometrics were obtained by a nutritionist or a

pediatrician. • Patients received a comprehensive ASD evaluation from

experienced clinicians using the ADOS and the ADI-R, yielding an ASD diagnosis or non-ASD disorder.

• 201 children evaluated through the University of Alabama at Birmingham Civitan-Sparks Clinics were included in these retrospective analyses through file review.

• Of the 201 children, 169 were males while 32 were females. • Of the 201 children, 111 were Caucasians, 44 were African

Americans, 4 Hispanic, and 42 were unknown.

Methods• Since both groups were significantly different in age,

head circumference, weight, and height percentiles were compared between the two groups instead of actual head circumference, weight, and height measurements.

• Each child is assigned a percentile based on his or her age and his or her head circumference, weight, or height measurement. The percentiles were separated into 4 groups:

• 0-25%• 26-50%• 51-75%• 76-100%

Participants

Autism Spectrum Disorder (ASD) Other Developmental Disorders (Other DD

N = 174 N = 27

Mean ADOS Score: 6.6SD = 1.85

Mean ADOS Score: 3.1SD = 1.95

Mean BMI = 20.2SD = 5.4

Mean BMI = 22.4SD = 17.9

Participants

Group 0-25% 26-50% 51-75% 76-100% Total

ASD Group 0 2 1 4 7

Other DD Group

2 2 2 6 12

Total 2 4 3 10 19

Head Circumference Percentile Comparison

Participants

Group 0-25% 26-50% 51-75% 76-100% Total

ASD Group 2 4 0 3 9

Other DD Group

5 3 4 2 14

Total 7 7 4 5 23

Height Percentile Comparison

Group 0-25% 26-50% 51-75% 76-100% Total

ASD Group 13 19 9 25 66

Other DD Group

2 4 4 4 14

Total 15 23 13 29 80

Weight Percentile Comparison

Results: Hypothesis 1

•No significant differences in physical characteristics were found between children with autism and children with other developmental disorders.

Category Chi-Squared Statistic

df p-value

Head Circumference Percentile

1.5 3 0.677

Weight Percentile

2.04 3 0.564

Height Percentile

4.8 3 0.190

Results: Hypothesis 2

• After performing a correlational test (Spearman correlation), no correlation was found between head circumference percentile and ADOS symptom severity. Hypothesis 2 was not supported. p-value = 0.693

Discussion• After performing chi-square tests, no significant differences were

found in physical characteristics between children with autism and children with other developmental disorders. Hypothesis 1 was not supported.

• After performing a correlational test (Spearman correlation), no correlation was found between head circumference percentile and ADOS symptom severity. Hypothesis 2 was not supported.

• In contrast to the aforementioned previous studies, the current study did not find any significant differences in physical characteristics between children with autism and children with other developmental disorders. However, the current study does add information to the growing literature because most studies have compared children with autism and typically-developing children while the current study compared children with autism and children with other developmental disorders.

Conclusions• Physical characteristics could perhaps provide a better

phenotype of autism, which would provide a better understanding of the disorder.

• Head circumference measurements could perhaps provide a better understanding of brain growth or neural development in children with autism.

• Weight and height could perhaps provide a better understanding of skeletal growth in children with autism.

Limitations

• The two groups were not of the same age. • Sample analyzed for each statistical

test was different and very small.

References

• Courshesne, E., Carper, R., and Akshoomoff, N. (2003). Evidence of Brain Overgrowth in the First Year of Life in Autism. Journal of the American Medical Association, 290 (3), 337-344.

• Torrey, E., Dhavale, D., Lawlor, J., and Yolken, R.(2004). Autism and Head Circumference in the First Year of Life. Biological Psychiatry 56, 892-894

• Suren, P., Stoletenberg, C., Bresnahan, M., Hirtz, D., Lie, K., Lipkin, I., Magnus, P., Kjennerud-Reichborn, T., Schjolberg, S., Susser, E., Oyen, A., Li, L., and Hornig, M. (2013). Early Growth Patterns in Children with Autism. Epidemiology 24 (5), 660-670.

• Chawarska, K., Campbell, D., Chen, L., Shic, F., Klin, A., Chang, J. (2011). Early Generalized Overgrowth in Boys With Autism. Arch Gen Psychiatry, 68 (10), 1021-2031.

• Dissanayake, C., Bui, Q., Huggins, R., and Loesch, D. (2006). Growth in Stature and Head Circumference in High-Functioning autism and Asperger Disorder During the Frist 3 Years of Life. Development and Psychopathology, 18, 381-393.

• 2014. Autism Speaks. http://www.autismspeaks.org/