Division of Cognitive and Behavioral Neurosciences, Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Sherman Hall Annex Room 114, Buffalo, NY, 14214, USA; Neuroscience Program, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA.
Department of Neurology and Multiple Sclerosis Center, Lady Davis Carmel Medical Center, Haifa, Israel; Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
Mult Scler Relat Disord. 2022 Jan;57:103349. doi: 10.1016/j.msard.2021.103349. Epub 2021 Oct 29.
Fatigue in people with multiple sclerosis (PwMS) can impact physical, cognitive, and psychosocial domains of daily life. The experience of fatigue in PwMS is thought to originate from the central nervous system, particularly for the domain of cognitive fatigue. Here, we tested the hypothesis that fatigue scores in PwMS would be significantly associated with an index of neural activity - the latency of the P100 of the visual evoked potential (VEP) - in line with the notion of a centralized origin of fatigue. We predicted that prolonged VEP latency would be associated with greater fatigue, and that this relationship would be the most pronounced within the domain of cognitive fatigue.
PwMS (n=249) completed the Modified Fatigue Impact Scale (Global, Physical, Cognitive, and Psychosocial scales of the MFIS) and Fatigue Severity Scale. VEP latency was obtained using an alternating checkerboard paradigm. We also examined the influence of depression (Beck Depression Inventory, second edition, BDI-II) and cognitive functioning (NeuroTrax testing battery) on the VEP/fatigue relationship.
Surprisingly, we observed that earlier (not later) VEP latency was significantly associated with higher MFIS Cognitive score. The negative relationship between VEP latency and cognitive fatigue was evident in PwMS that had poor cognitive performance as measured by a latent variable that reflected attention, executive function, information processing speed, and motor skills; but a significant relationship was not observed in PwMS that exhibited good performance on this measure.
These findings can be interpreted within a metacognitive framework - greater fatigue may be perceived when neural performance and the level of mental effort expended does not translate to efficient cognitive performance. Cognitive fatigue may be particularly salient in PwMS when neural resources are unable to compensate for cognitive difficulties. The mismatch between the expectation of what ought to occur and what does occur during cognitive performance may be a key feature of the experience of cognitive fatigue for some PwMS.
多发性硬化症（MS）患者的疲劳会影响其日常生活的身体、认知和社会心理领域。MS 患者的疲劳体验被认为源自中枢神经系统，特别是认知疲劳领域。在这里，我们检验了这样一个假设，即 MS 患者的疲劳评分与神经活动指标（视觉诱发电位（VEP）的 P100 潜伏期）显著相关，这与疲劳的集中起源概念一致。我们预测，较长的 VEP 潜伏期与更大的疲劳相关，并且这种关系在认知疲劳领域最为明显。
249 名 MS 患者完成了改良疲劳影响量表（MFIS 的整体、身体、认知和社会心理量表）和疲劳严重程度量表。使用交替棋盘范式获得 VEP 潜伏期。我们还检查了抑郁（贝克抑郁量表第二版，BDI-II）和认知功能（NeuroTrax 测试电池）对 VEP/疲劳关系的影响。
令人惊讶的是，我们观察到较早（而不是较晚）的 VEP 潜伏期与较高的 MFIS 认知评分显著相关。VEP 潜伏期与认知疲劳之间的负相关关系在认知表现较差的 MS 患者中明显存在，这表现在反映注意力、执行功能、信息处理速度和运动技能的潜在变量上；但在认知表现良好的 MS 患者中，并未观察到显著的相关性。
这些发现可以在元认知框架内进行解释——当神经表现和所付出的心理努力水平不能转化为有效的认知表现时，可能会感到更大的疲劳。当神经资源无法补偿认知困难时，认知疲劳可能在 MS 患者中尤为突出。在认知表现过程中，期望发生的事情与实际发生的事情之间的不匹配可能是某些 MS 患者认知疲劳体验的一个关键特征。
