11月8日,美国研究人员公布了一项小型研究结果显示，与普通儿童相比，自闭症患儿大脑前额叶皮层的神经元数量过多。这项发现有助理解自闭症的病因。
前额叶皮层是大脑中最重要的区域之一，参与人体的语言、交流、社会行为、情绪以及注意力等高级功能。自闭症患儿的这些高级功能通常有所欠缺。
美国加利福尼亚州圣迭戈大学的研究人员对7名自闭症患儿及6名普通男孩的前额叶皮层进行了检查，这些男孩的年龄在2至16岁之间。结果发现，自闭症患儿前额叶的神经元数量比普通儿童多67%，其平均脑重量也更重。
这项研究成果9日将发表在新一期《美国医学会杂志》上。研究人员表示，由于皮层神经元在患儿出生前而不是出生后产生，这表明自闭症的出现可能与患儿胎儿期的神经细胞生长或维持出现错误有关，另一个导致患儿神经元过多的可能因素是其细胞凋亡机制出现紊乱。（生物谷 Bioon.com)
doi:10.1001/jama.2011.1638
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Neuron Number and Size in Prefrontal Cortex of Children With Autism
Courchesne, Eric; Mouton, Peter R.; Calhoun, Michael E.; Semendeferi, Katerina; Ahrens-Barbeau, Clelia; Hallet, Melodie J.; Barnes, Cynthia Carter; Pierce, Karen
Context 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.
Main Outcome Measures 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.
Conclusion In this small preliminary study, brain overgrowth in males with autism involved an abnormal excess number of neurons in the PFC.
