Kennedy P J, Clarke G, O'Neill A, Groeger J A, Quigley E M M, Shanahan F, Cryan J F, Dinan T G
Alimentary Pharmabiotic Centre, University College Cork, Ireland.
Department of Psychology, University of Hull, UK.
Psychol Med. 2014 May;44(7):1553-66. doi: 10.1017/S0033291713002171. Epub 2013 Aug 29.
Central nervous system (CNS) dysfunction is a prominent feature of the functional gastrointestinal (GI) disorder, irritable bowel syndrome (IBS). However, the neurobiological and cognitive consequences of key pathophysiological features of IBS, such as stress-induced changes in hypothalamic-pituitary-adrenal (HPA)-axis functioning, is unknown. Our aim was to determine whether IBS is associated with cognitive impairment, independently of psychiatric co-morbidity, and whether cognitive performance is related to HPA-axis function.
A cross-sectional sample of 39 patients with IBS, a disease control group of 18 patients with Crohn's disease (CD) in clinical remission and 40 healthy age- and IQ-matched control participants were assessed using the Paired Associates Learning (PAL), Intra-Extra Dimensional Set Shift (IED) and Spatial Working Memory (SWM) tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB) and a computerized Stroop test. HPA-axis function was determined by measuring the cortisol awakening response (CAR).
IBS patients exhibited a subtle visuospatial memory deficit at the PAL six- pattern stage (p = 0.03), which remained after psychiatric co-morbidity was controlled for (p = 0.04). Morning cortisol levels were lower in IBS (p = 0.04) and significantly associated with visuospatial memory performance within IBS only (p = 0.02).
For the first time, altered cognitive function on a hippocampal-mediated test of visuospatial memory, which was related to cortisol levels and independent of psychiatric co-morbidity, has been identified in IBS. Visuospatial memory impairment may be a common, but currently neglected, component of IBS. Further elucidation of the nature of this impairment may lead to a greater understanding of the underlying pathophysiology of IBS, and may provide novel therapeutic approaches.
中枢神经系统（CNS）功能障碍是功能性胃肠（GI）疾病——肠易激综合征（IBS）的一个突出特征。然而，IBS关键病理生理特征的神经生物学和认知后果，如应激引起的下丘脑-垂体-肾上腺（HPA）轴功能变化，尚不清楚。我们的目的是确定IBS是否与认知障碍相关（独立于精神共病），以及认知表现是否与HPA轴功能有关。
使用来自剑桥神经心理测试自动成套系统（CANTAB）的配对联想学习（PAL）、维度内-维度间转换（IED）和空间工作记忆（SWM）测试以及计算机化斯特鲁普测试，对39例IBS患者的横断面样本、18例处于临床缓解期的克罗恩病（CD）患者的疾病对照组和40名年龄及智商匹配的健康对照参与者进行评估。通过测量皮质醇觉醒反应（CAR）来确定HPA轴功能。
IBS患者在PAL六模式阶段表现出轻微的视觉空间记忆缺陷（p = 0.03），在控制精神共病后该缺陷仍然存在（p = 0.04）。IBS患者的早晨皮质醇水平较低（p = 0.04），并且仅在IBS患者中与视觉空间记忆表现显著相关（p = 0.02）。
首次在IBS中发现，在海马介导的视觉空间记忆测试中认知功能改变，该改变与皮质醇水平相关且独立于精神共病。视觉空间记忆损害可能是IBS常见但目前被忽视的一个组成部分。进一步阐明这种损害的性质可能会加深对IBS潜在病理生理学的理解，并可能提供新的治疗方法。
