Why and when the difference in head circumference in autism begins?

Abstract

Objective: We aimed to investigate the head circumference (HC) and body length (BL) difference between patients with autism, with disruptive behavior disorder (DBD) and without any diagnosis (ND) and to explore the critical periods of age that the acceleration in the enlargement is significant among children younger than 3 and a half years old,. Methods: Clinical psychiatric evaluation of all patients (n=90) younger than 43 months old ( mean: 30.88 +/- 8.06) were made comprehensively and parents were given Autistic Behavior Checklist (ABC), Child Behavior Checklist 2/3 (CBCL). HC, BL and body weight were measured in a standard way. Results: Only within the group of 2-3 years old children, the AU were found to have significantly longer HC (p<0.001) and BL (p<0.001) with respect to non-AU and post-hoc analysis revealed that AU had larger heads with respect to ND (p=0.007) and DBD (p=0.04), longer height only with respect to ND (p=0.017). We also found several significant correlations between BL and ABC scores (e.g., ABC-[total, p=0.017, r=0.41]). Conclusion: Accelerated growth in BL, as well as HC, which becomes obvious after age two and decelerates after age three, may be an indicator of autism and a differentiating feature from DBD in early ages. The pathophysiology that would explain the correlation found between autistic symptom severity and acceleration in body length increase is yet to be investigated.