Huntington and Rare Diseases Unit, IRCCS Casa Sollievo della Sofferenza Hospital (Rome CSS-Mendel), Viale Cappuccini, 1, 71013, San Giovanni Rotondo, Italy.
Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, Via Vetoio, 67100, Coppito, AQ, Italy.
Parkinsonism Relat Disord. 2019 Mar;60:111-117. doi: 10.1016/j.parkreldis.2018.09.007. Epub 2018 Sep 5.
Huntington's Disease (HD) cognitive dysfunction occurs before unequivocal motor signs become apparent. The predominant early cognitive abnormal domains may include deficits in psychomotor speed, negative emotion recognition and executive functioning. Our study is aimed to investigate the executive control of cognition in pre-manifest (pre) HD subjects, by means of a task-switching protocol.
We recruited 30 pre-HD subjects and 18 age-, sex- and education-matched Healthy Controls (HC). Subjects were assigned to two experimental groups: 15 pre-HD1 with a Total Motor Score (TMS) ≤4 (far from onset) and 15 pre-HD2 with a 5 ≤ TMS≤9 (near to onset and Diagnostic Confidence Level (DCL) still<4). Two different tasks were performed in rapid and random succession, so that the task was either changed from one trial to the next one (switch trials) or repeated (repetition trials). Switch trials are usually slower than repetitions, causing a so-called Switch Cost (SC).
Pre-HD subjects had worse performance than HC in the switch and repetition trials, as indicated by increased SC and reaction times. In particular, pre-HD2 showed impaired switching abilities with reaction times slower than pre-HD1 and HC.
Our study highlighted a task-switching impairment since HD was still at a pre-manifest stage. Such abnormalities worsen when pre-HD subjects start to show subtle motor manifestations, still nonspecific and insufficient to define the clinical diagnosis of HD (DCL<4). Considering that such abilities have obvious implications for activities of daily living, early cognitive rehabilitation programs addressing such deficits might be useful in the premanifest stage of the disease.
亨廷顿病（HD）认知功能障碍发生在明确的运动症状出现之前。主要的早期认知异常领域可能包括运动速度、负性情绪识别和执行功能的缺陷。我们的研究旨在通过任务转换协议来研究前显型（pre）HD 受试者的认知执行控制。
我们招募了 30 名 pre-HD 受试者和 18 名年龄、性别和教育程度相匹配的健康对照者（HC）。受试者被分为两组：15 名 pre-HD1，总运动评分（TMS）≤4（远离发病），15 名 pre-HD2，5≤TMS≤9（接近发病且诊断置信水平（DCL）仍<4）。两种不同的任务快速且随机地连续进行，因此任务要么从一个试验切换到下一个试验（切换试验），要么重复（重复试验）。切换试验通常比重复试验慢，导致所谓的切换成本（SC）。
pre-HD 受试者在切换和重复试验中的表现均不如 HC，表现为 SC 和反应时间增加。特别是，pre-HD2 的切换能力受损，反应时间比 pre-HD1 和 HC 慢。
我们的研究强调了 HD 仍处于前显型阶段时就存在的任务转换障碍。当 pre-HD 受试者开始出现微妙的运动表现时，这些异常会恶化，这些表现仍然是非特异性的，不足以确定 HD 的临床诊断（DCL<4）。考虑到这些能力对日常生活活动有明显的影响，针对这些缺陷的早期认知康复计划可能在疾病的前显型阶段有用。
