For more than 60 years it has been known that some people with autism have abnormally large heads. Now, a group from the University of California San Diego has described an aberrant pattern of head growth that might provide an early warning of the onset of this increasingly prevalent disorder.

Led by E. Courchesne, the team examined the medical records of normal children and infants with autism between the ages of 6 and 14 months. The head size of 60% of the patients was significantly above average, and the severity of their symptoms was positively correlated with head circumference. Interestingly, head size at birth was below average in the affected group, indicating that a growth spurt of unusual magnitude had occurred during their first year.

During development, steady brain growth allows synapses to form then be reinforced or eliminated, according to sensory and motor inputs. Courchesne told the Seattle Post-Intelligencer (16 July 2003) that rapid enlargement might inhibit “the guidance of experience and learning, [causing] the brain [to create] abnormal connections that make it very hard for autistic children to make sense of the world they live in”.

As this pattern of head development can be detected long before the onset of behavioural symptoms, the already routine measurement of the head circumference of infants will yield an early warning to parents of those at risk. As the father of a child with autism, R. Rollens of the MIND Institute is all too aware that “it's better to know as early as possible that something might be wrong” (Los Angeles Times, USA, 16 July 2003).