Guglielmi Valeria, Quaranta Davide, Mega Ilaria, Costantini Emanuele Maria, Carrarini Claudia, Innocenti Alice, Marra Camillo
Neurology Unit, Fondazione Policlinico Agostino Gemelli-IRCCS, 00168 Rome, Italy.
Department of Neuroscience, Catholic University of Sacred Heart, 00168 Rome, Italy.
J Pers Med. 2020 Jun 29;10(3):57. doi: 10.3390/jpm10030057.
Semantic memory is impaired in mild cognitive impairment (MCI). Twomain hypotheses about this finding are debated and refer to the degradation of stored knowledgeversus the impairment of semantic access mechanisms. The aim of our study is to evaluate semanticimpairment in MCI versus healthy subjects (HS) by an experiment evaluating semantic priming.
We enrolled 27 MCI and 20 HS. MCI group were divided, according to follow up, intoconverters-MCI and non converters-MCI. The semantic task consisted of 108 pairs of words, 54 ofwhich were semantically associated. Stimuli were presented 250 or 900 ms later the appearance ofthe target in a randomized manner. Data were analyzed using factorial ANOVA.
Both HSand MCI answered more quickly for word than for non-word at both stimulus onset asynchrony(SOA) intervals. At 250 ms, both MCI and HS experienced a shorter time of response for relatedwordthan for unrelated words (priming effect), while only the converters-MCI subgroup lost thepriming effect. Further, we observed a rather larger Cohen's d effect size in non converters-MCIthan in converters-MCI.
Our data, and in particular the absence of a semantic primingeffect in converters-MCI, could reflect the impairment of semantic knowledge rather than theaccessibility of semantic stores in MCI individuals that progress to dementia.
轻度认知障碍（MCI）患者的语义记忆受损。关于这一发现的两个主要假设存在争议，分别涉及存储知识的退化与语义通达机制的损害。我们研究的目的是通过一项评估语义启动的实验，来评估MCI患者与健康受试者（HS）之间的语义损害情况。
我们招募了27名MCI患者和20名健康受试者。根据随访情况，MCI组被分为转化型MCI和非转化型MCI。语义任务由108对单词组成，其中54对在语义上相关。刺激在目标出现后250毫秒或900毫秒以随机方式呈现。使用析因方差分析对数据进行分析。
在两个刺激起始异步（SOA）间隔下，HS组和MCI组对单词的反应都比对非单词的反应更快。在250毫秒时，MCI组和HS组对相关单词的反应时间都比对不相关单词的反应时间短（启动效应），而只有转化型MCI亚组失去了启动效应。此外，我们观察到非转化型MCI组的科恩d效应量比转化型MCI组的更大。
我们的数据，特别是转化型MCI组中缺乏语义启动效应，可能反映了MCI患者进展为痴呆时语义知识的损害，而非语义存储的可及性损害。
