Autistic kids have heavier brains
18 November 2011
An excess of neurons (nerve cells) is responsible for the abnormal enlargement of the brain seen in early childhood in many children with autism, a US study suggests (JAMA 2011; 306: 2001-10).
The small study of tissue taken after death from 7 boys aged 2-16 with autism showed they had 67 per cent more neurons in a part of the brain known as the prefrontal cortex compared with 6 male children and adolescents without autism (controls). The prefrontal cortex is the area of the brain immediately behind the forehead.
Children with autism had brain weights for age that differed by 18 per cent from normal compared with a difference of only 0.2 per cent in controls.
"Because cortical [brain] neurones are not generated [after birth], this pathological increase in neuron numbers in autistic children indicates prenatal causes," the authors said.
In an editorial, US psychiatrists said the data, together with other advances, may indicate "autism research is at last turning a corner" (JAMA 2011; 306: 2031-2).
Last Reviewed: 18 November 2011
- 1. Courchesne E, Mouton PR, Calhoun ME, et al. Neuron number and size in prefrontal cortex of children with autism. JAMA 2011; 306: 2001-10. doi: 10.1001/jama.2011.1638. http://jama.ama-assn.org/content/306/18/2001.long (accessed Nov 2011).
2. Lainhart JE, Lange N. Increased neuron number and head size in autism [editorial]. JAMA 2011; 306: 2031-2. doi: 10.1001/jama.2011.1633. http://jama.ama-assn.org/content/306/18/2031.extract (accessed Nov 2011).
