Clinical, morphological, and biochemical correlates of head circumference in autism

Biol Psychiatry. 2007 Nov 1;62(9):1038-47. doi: 10.1016/j.biopsych.2007.04.039. Epub 2007 Jul 20.


Background: Head growth rates are often accelerated in autism. This study is aimed at defining the clinical, morphological, and biochemical correlates of head circumference in autistic patients.

Methods: Fronto-occipital head circumference was measured in 241 nonsyndromic autistic patients, 3 to 16 years old, diagnosed according to DSM-IV criteria. We assessed 1) clinical parameters using the Autism Diagnostic Observation Schedule, Autism Diagnostic Interview-Revised, Vineland Adaptive Behavioral Scales, intelligence quotient measures, and an ad hoc clinical history questionnaire; 2) height and weight; 3) serotonin (5-HT) blood levels and peptiduria.

Results: The distribution of cranial circumference is significantly skewed toward larger head sizes (p < .00001). Macrocephaly (i.e., head circumference >97th percentile) is generally part of a broader macrosomic endophenotype, characterized by highly significant correlations between head circumference, weight, and height (p < .001). A head circumference >75th percentile is associated with more impaired adaptive behaviors and with less impairment in IQ measures and motor and verbal language development. Surprisingly, larger head sizes are significantly associated with a positive history of allergic/immune disorders both in the patient and in his/her first-degree relatives.

Conclusions: Our study demonstrates the existence of a macrosomic endophenotype in autism and points toward pathogenetic links with immune dysfunctions that we speculate either lead to or are associated with increased cell cycle progression and/or decreased apoptosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Age Factors
  • Analysis of Variance
  • Autistic Disorder / blood*
  • Autistic Disorder / pathology*
  • Body Weight
  • Cephalometry / methods
  • Child
  • Child Development / physiology
  • Child, Preschool
  • Craniofacial Abnormalities / pathology
  • Female
  • Head / growth & development*
  • Head / pathology*
  • Humans
  • Intelligence
  • Male
  • Physical Examination
  • Reference Values
  • Regression Analysis
  • Serotonin / blood*


  • Serotonin