International Meeting for Autism Research (May 7 - 9, 2009): Early Development of Head Circumference in Autistic Children: Searching Clinical Subtypes

Thursday, May 7, 2009

Northwest Hall (Chicago Hilton)

3:30 PM

F. Muratori , Division of Child Neurology and Psychiatry, University of Pisa – Stella Maris Scientific Institute, Pisa, Italy

M. Telleschi , Division of Child Neurology and Psychiatry, University of Pisa – Stella Maris Scientific Institute, Pisa, Italy

E. Santocchi , Division of Child Neurology and Psychiatry, University of Pisa – Stella Maris Scientific Institute, Pisa, Italy

R. Tancredi , Division of Child Neurology and Psychiatry, University of Pisa – Stella Maris Scientific Institute, Pisa, Italy

R. Igliozzi , Division of Child Neurology and Psychiatry, University of Pisa – Stella Maris Scientific Institute, Pisa, Italy

B. Parrini , Division of Child Neurology and Psychiatry, University of Pisa – Stella Maris Scientific Institute, Pisa, Italy

F. Apicella , Division of Child Neurology and Psychiatry, University of Pisa – Stella Maris Scientific Institute, Pisa, Italy

A. Narzisi , Division of Child Neurology and Psychiatry, University of Pisa – Stella Maris Scientific Institute, Pisa, Italy

S. Calderoni , Division of Child Neurology and Psychiatry, University of Pisa – Stella Maris Scientific Institute, Pisa, Italy

Background:

Since the first Kanner’s description of Autistic Disorder, several researchers have analyzed and described the presence of an early abnormal development of head circumference in a subgroup of autistic patients who ranges from 14% to 34% in the different studies. This particular developmental trend suggest the presence of an underlying abnormal cerebral development during the first months of life and more recently it has been studied the correlation both to neuroimaging data and to clinical and neuropsychological phenotype and outcome of affected children.

Objectives:

To describe the timing of head circumference (HC) development during the first 18 months of life in patients with autism spectrum disorder (ASD). To identify subgroups of children on the basis of different pathways in early HC development and later clinical outcome.

Methods:

Longitudinal data of HC, body length and body weight during the first 18 months of life were obtained from the pediatric medical records of 50 children with ASD. All patients met DSM-IV-R criteria for ASD diagnosis which was confirmed by ADOS and CARS. IQ levels and adaptive functioning were determined respectively through psychometric tests and VABS.

Results:

More than two third of patients shows an abnormal significant increase in HC beginning at 3-5 months compared to normative data of healthy infants. In a small number of ASD children the abnormal brain growth starts from a reduced head size at birth reaching a HC normalization at the current evaluation. Another subgroup of ASD patients starts with non significant HC rate and reaches a brain size exceeding 50° percentile or macrocephaly during the first 18 months of life. Only a minority of patients shows a substantial stability or a decrease in the HC size during early infancy. Some differences have been found between types of longitudinal pathways of HC and clinical outcome.

Conclusions:

Our study confirms the evidence of a critical period in early HC development in children later diagnosed with ASD. This excessive increase occurs well before the typical onset of clinical behavioral symptoms, and it may serve as an early warning signal of risk for autism. Thus, it holds potential for clinical application because it is early, rapid, common across patients, and its detection is simple, noninvasive and objective. The hypotheses that the magnitude of abnormal HC development during infancy might be related to the severity of later clinical outcome is not confirmed, while a reduced HC at birth is significant related to a poorer outcome in cognitive level.

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