title: Neuron number and size in prefrontal cortex of children with autism.
abstract: BACKGROUND
  Autism often involves early brain overgrowth, including the prefrontal cortex (PFC). Although prefrontal abnormality has been theorized to underlie some autistic symptoms, the cellular defects that cause abnormal overgrowth remain unknown.
  
  
  OBJECTIVE
  To investigate whether early brain overgrowth in children with autism involves excess neuron numbers in the PFC. DESIGN, SETTING, AND CASES: Postmortem prefrontal tissue from 7 autistic and 6 control male children aged 2 to 16 years was examined by expert anatomists who were blinded to diagnostic status. Number and size of neurons were quantified using stereological methods within the dorsolateral (DL-PFC) and mesial (M-PFC) subdivisions of the PFC. Cases were from the eastern and southeastern United States and died between 2000 and 2006.
  
  
  METHODS
  Mean neuron number and size in the DL-PFC and M-PFC were compared between autistic and control postmortem cases. Correlations of neuron number with deviation in brain weight from normative values for age were also performed.
  
  
  RESULTS
  Children with autism had 67% more neurons in the PFC (mean, 1.94 billion; 95% CI, 1.57-2.31) compared with control children (1.16 billion; 95% CI, 0.90-1.42; P = .002), including 79% more in DL-PFC (1.57 billion; 95% CI, 1.20-1.94 in autism cases vs 0.88 billion; 95% CI, 0.66-1.10 in controls; P = .003) and 29% more in M-PFC (0.36 billion; 95% CI, 0.33-0.40 in autism cases vs 0.28 billion; 95% CI, 0.23-0.34 in controls; P = .009). Brain weight in the autistic cases differed from normative mean weight for age by a mean of 17.6% (95% CI, 10.2%-25.0%; P = .001), while brains in controls differed by a mean of 0.2% (95% CI, -8.7% to 9.1%; P = .96). Plots of counts by weight showed autistic children had both greater total prefrontal neuron counts and brain weight for age than control children.
  
  
  CONCLUSIONS
  In this small preliminary study, brain overgrowth in males with autism involved an abnormal excess number of neurons in the PFC.
authors: Department of Neuroscience, NIH-UCSD Autism Center of Excellence, School of Medicine, University of California San Diego, La Jolla, CA 92093, USA. ecourchesne@ucsd.edu
authors: Eric
authors: E
authors: Courchesne
authors: Peter R
authors: PR
authors: Mouton
authors: Michael E
authors: ME
authors: Calhoun
authors: Katerina
authors: K
authors: Semendeferi
authors: Clelia
authors: C
authors: Ahrens-Barbeau
authors: Melodie J
authors: MJ
authors: Hallet
authors: Cynthia Carter
authors: CC
authors: Barnes
authors: Karen
authors: K
authors: Pierce
mesh_terms: D000293:Adolescent; D001321:Autistic Disorder / Q000473:pathology*; D001344:Autopsy; D016022:Case-Control Studies; D002452:Cell Count; D048429:Cell Size; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D008297:Male; D009474:Neurons / Q000166:cytology*; D009929:Organ Size; D017397:Prefrontal Cortex / Q000166:cytology* / Q000254:growth & development* / Q000473:pathology