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Abstract
心的外傷後ストレス障害(PTSD)の臨床研究は,affective neuroscienceにおけるストレス脆弱性の脳基盤の研究と相互作用して進展している.一連の神経画像研究から,恐怖条件づけの形成・消去に重要な内側前頭皮質(前部帯状回を含む)と辺縁系(扁桃体・海馬)の相互連絡がPTSDの脳病態の中心として浮き彫りにされた.PTSDにおける脳障害がPTSDに至る脆弱性因子か,心的外傷に曝露された後の獲得性因子かについては,双生児を対象としたMRI研究から,海馬体積減少が脆弱性因子であることが示唆されている.近年,ストレス脆弱性に関わる内側前頭皮質・辺縁系の神経発達に,遺伝と養育環境の相互作用が関わっていることが明らかにされつつある.PTSDを含む不安・うつ病スペクトラム障害における遺伝的素因と環境要因の時期依存性や質的特徴を選り分けていくことが,ストレス脆弱性の脳基盤の統合的解明に資するであろう.神経画像は,PTSDやストレス脆弱性の脳病態解明のみならず,診断や治療効果判定などの臨床応用可能性にも期待がもたれる.
This review describes structural and functional neuroimaging studies of posttraumatic stress disorder (PTSD). First, a combined structural MRI, diffusion tensor imaging, and event-related potential study in victims of Tokyo sub- way sarin attack revealed left anterior cingulate cortex (ACC) volume reduction which was tightly coupled with P300 amplitude reduction, and aberrant anterior cingulum integrity in PTSD patients. In a monozygotic twin study of US combat veterans, we found a significant volume reduction in the hippocampus in both combat-exposed PTSD subjects and their co-twins compared with both combat-exposed non-PTSD subjects and their co-twins. These results suggest that cortical abnormalities in PTSD may be characterized by those in limbic regions and medial prefrontal cortex that regulate the limbic regions. These abnormalities may at least in part represent pre-existing vulnerability to PTSD. Characterizing gene-environment interaction in the formation of medial prefrontal and limbic abnormalities will be important to uncover brain mechanisms for stress vulnerability and anxiety and depression spectrum disorders. Neuroimaging will be also a powerful tool for clinical application such as diagnosis and objective monitoring of treatment response in stress related disorders.
Journal
- Japanese Journal of Psychosomatic Medicine [List of Volumes]
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Japanese Journal of Psychosomatic Medicine 47(8), 713-719, 2007-08-01 [Table of Contents]
Japanese Society of Psychosomatic Medicine
