2012年2月13日，PNAS杂志刊登了一项研究表明，儿童时期受到身体及精神虐待，会导致成年人大脑中某些非常重要的区域萎缩，减少大脑海马体体积，而海马体与人的认知能力、记忆力、情绪控制力相关。
研究人员使用核磁共振成像技术对193位18到25岁青年进行大脑扫描，然后研究人员为他们做了一份详细的个人经历调查。结果显示，那些儿时受过虐待、漠视的人，大脑海马体比健康成长的人平均小6%。
除了海马体，脑下脚也受到影响，脑下脚负责将海马体的信号传播给大脑其他区域，如多巴胺系统，多巴胺也被称为大脑的奖赏中枢。脑下脚的缩小会增加成年后患精神分裂症和药物滥用的风险。
在灵长类动物试验中，当压力荷尔蒙皮质醇接收到过大的压力时，海马体就会缩小。科学家发现这是因为压力荷尔蒙水平过高抑制了海马体中神经元的生长。而海马体的缩小主要在两个阶段，一个是3岁到5岁，一个是11岁到13岁。
这项研究也解释了为什么心理学家总是将许多成年人的精神疾病，如抑郁、焦虑、药物滥用等归因于幼儿时期。哈佛大学研究人员Martin Teicher表示，儿童时受到虐待几乎能等同于成年后的精神疾病和药物滥用。(生物谷 Bioon.com)
doi:10.1073/pnas.1115396109
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Childhood maltreatment is associated with reduced volume in the hippocampal subfields CA3, dentate gyrus, and subiculum
Martin H. Teicher, Carl M. Anderson, and Ann Polcari
Childhood maltreatment or abuse is a major risk factor for mood, anxiety, substance abuse, psychotic, and personality disorders, and it is associated with reduced adult hippocampal volume, particularly on the left side. Translational studies show that the key consequences of stress exposure on the hippocampus are suppression of neurogenesis in the dentate gyrus (DG) and dendritic remodeling in the cornu ammonis (CA), particularly the CA3 subfield. The hypothesis that maltreatment is associated with volume reductions in 3-T MRI subfields containing the DG and CA3 was assessed and made practical by newly released automatic segmentation routines for FreeSurfer. The sample consisted of 193 unmedicated right-handed subjects (38% male, 21.9 ± 2.1 y of age) selected from the community. Maltreatment was quantified using the Adverse Childhood Experience study and Childhood Trauma Questionnaire scores. The strongest associations between maltreatment and volume were observed in the left CA2-CA3 and CA4-DG subfields, and were not mediated by histories of major depression or posttraumatic stress disorder. Comparing subjects with high vs. low scores on the Childhood Trauma Questionnaire and Adverse Childhood Experience study showed an average volume reduction of 6.3% and 6.1% in the left CA2-CA3 and CA4-DG, respectively. Volume reductions in the CA1 and fimbria were 44% and 60% smaller than in the CA2-CA3. Interestingly, maltreatment was associated with 4.2% and 4.3% reductions in the left presubiculum and subiculum, respectively. These findings support the hypothesis that exposure to early stress in humans, as in other animals, affects hippocampal subfield development.
