기저 코티솔 수준에 따른해마의 기능적 비대칭성 = Basal cortisol level and functional asymmetry of the hippocampus

다국어 초록 (Multilingual Abstract)

It is well known that extreme stress or continually elevated glucocorticoid levels induce functional deficit and volume reduction in the hippocampus. However, it remains unknown whether stress induces the asymmetry of the hippocampus. To explore the effect of stress on the functional asymmetry of the hippocampus, we investigated an association between basal cortisol levels and the hippocampal asymmetry in the regional cerebral glucose metabolism in 44 right-handed normal elderly female participants (mean age 69.16 ± 4.6). Participants underwent [18F] fluorodeoxyglucose PET scanning during resting state and were assessed basal salivary cortisol levels during daytime. In order to investigate the association between stress related-hippocampal asymmetry and cognitive functions, we compared high-asymmetry group and low-asymmetry group with performance of the Korean-Dementia Rating Scale(K-DRS). We found that diurnal cortisol range was positively correlated with the degree of asymmetry of hippocampal glucose metabolic rates. Also, the K-DRS scores were lower than in the high-asymmetry group than those in the low-asymmetry group. These results suggests that stress may disrupt the bilateral balance in the hippocampal function, which may accelerate cognitive aging.

국문 초록 (Abstract)

심한 스트레스나 만성적인 스트레스는 대뇌의 구조 및 기능에 부정적인 영향을 미친다. 특히 해마는 스트레스로 인해 축소되고 기능이 저하되는 영역으로 알려졌는데, 대뇌 스트레스 반응의 좌우 비대칭성이나 해마 코티솔 수용체의 좌우 비대칭적 분포를 고려하면 스트레스는 해마의 좌우 비대칭성 역시 변화시킬 것으로 예상된다. 그러나 스트레스와 해마의 기능적 좌우 비대칭성 간의 관계는 아직 분명히 밝혀지지 않았다. 본 연구는 스트레스가 해마의 기능적 좌우 비대칭성에 미치는 영향을 알아보고자 44명의 정상 노인들을 대상으로 코티솔의 일과 중 기저 수준과 해마의 좌우 안정기 당대사율(FDG-PET 사용)을 측정했고, 기저 코티솔 측정치와 해마 당대사율의 좌우 비대칭성 간의 상관관계를 탐색했다. 또한 스트레스와 관련된 해마의 기능적 좌우 비대칭성이 인지 노화에 시사하는 바를 알아보기 위해, 안정기 해마 당대사율의 좌우 비대칭성 정도가 높은 집단과 낮은 집단 간의 인지 기능을 비교 분석했다. 연구 결과, 일과 중 기저 코티솔 변화량이 클수록 안정기 해마 당대사율의 좌우 비대칭성의 정도가 높은 것으로 나타났으며, 해마의 좌우 기능적 비대칭성의 정도가 높은 집단은 낮은 집단에 비해 K-DRS로 측정한 인지 기능이 유의하게 저조했다. 이러한 결과는 일과 중 기저 코티솔 수준의 변화가 클수록 해마의 좌우 당대사의 불균형이 초래될 가능성을 시사함과 동시에, 스트레스로 인한 해마의 기능적 좌우 비대칭성의 변화가 정상 노화 과정 중 인지 노화를 촉진시킬 가능성을 시사한다.

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