Carolina Institute for Developmental Disabilities and the Department of Psychiatry, University of North Carolina, Chapel Hill, USA.
Am J Psychiatry. 2012 Jun;169(6):601-8. doi: 10.1176/appi.ajp.2012.11091425.
Individuals with autism as young as 2 years have been observed to have larger brains than healthy comparison subjects. Studies using head circumference suggest that brain enlargement is a postnatal event that occurs around the latter part of the first year. To the authors' knowledge, no previous brain imaging studies have systematically examined the period prior to age 2. In this study they used magnetic resonance imaging (MRI) to measure brain volume in 6-month-olds at high familial risk for autism.
The Infant Brain Imaging Study (IBIS) is a longitudinal imaging study of infants at high risk for autism. This cross-sectional analysis compared brain volumes at 6 months of age in high-risk infants (N=98) and infants without family members with autism (N=36). MRI scans were also examined for radiologic abnormalities
No group differences were observed for intracranial, cerebrum, cerebellum, or lateral ventricle volume or for head circumference.
The authors did not observe significant group differences for head circumference, brain volume, or abnormalities in radiologic findings from a group of 6-month-old infants at high risk for autism. The authors are unable to conclude that these abnormalities are not present in infants who later go on to receive a diagnosis of autism; rather, abnormalities were not detected in a large group at high familial risk. Future longitudinal studies of the IBIS study group will examine whether brain volume differs in infants who go on to develop autism.
研究人员观察到，2 岁以下的自闭症个体的大脑比健康对照组的大脑要大。使用头围的研究表明，脑增大是一种出生后的事件，发生在第一年的后期。据作者所知，以前没有脑成像研究系统地检查过 2 岁之前的时期。在这项研究中，他们使用磁共振成像（MRI）测量了自闭症高风险 6 个月大婴儿的脑容量。
婴儿脑成像研究（IBIS）是一项针对自闭症高风险婴儿的纵向成像研究。这项横断面分析比较了高风险婴儿（N=98）和没有自闭症家族成员的婴儿（N=36）在 6 个月大时的脑容量。还检查了 MRI 扫描的放射学异常。
两组在颅内、大脑、小脑或侧脑室体积或头围方面均无差异。
作者在一组自闭症高风险的 6 个月大婴儿中，未观察到头围、脑容量或放射学发现异常的显著组间差异。作者无法得出这些异常在后来被诊断为自闭症的婴儿中不存在的结论；相反，在高家族风险的大群体中没有检测到异常。IBIS 研究组的未来纵向研究将检查在后来发展为自闭症的婴儿中，脑容量是否存在差异。
