Octogone-Lordat Interdisciplinary Research Unit (EA 4156), University of Toulouse II-Jean Jaurès, Toulouse, France; Toulouse NeuroImaging Center, University of Toulouse, Inserm, UPS, France.
Toulouse NeuroImaging Center, University of Toulouse, Inserm, UPS, France; Neurology Department, Neuroscience Centre, Toulouse University Hospital, Toulouse, France.
Neuropsychologia. 2019 Feb 18;124:133-143. doi: 10.1016/j.neuropsychologia.2018.12.018. Epub 2018 Dec 26.
Lexical-semantic impairment is one of the earliest symptoms of Alzheimer's disease (AD) and is usually examined by single word processing tasks. During speech production, pauses are often investigated as a hallmark of a patient's lexical-semantic decline. In the current study, we put forward the hypothesis that pauses reflect different processes according to the type of discourse. We believe that lexical and semantic impairment would predict a patient's pause frequency in a picture-based narrative (PBN) while anterograde memory would predict a patient's pause frequency in a memory-based narrative (MBN). To demonstrate this, we recruited 17 early AD patients and 17 matched controls. They underwent a full neuropsychological and language assessment and two narrative production assessments. We compared pause duration and frequency in the AD participants' and healthy controls' PBN and MBN. A multiple regression model was used in each narrative and in each group individually to assess the relationship between cognitive processes and pause frequency. Our results show that participants with AD produced more pauses in the PBN only. The frequency was predicted by semantic fluency performance with which it was positively correlated, contrary to what was expected. In the MBN, pause frequency in the AD participants was positively correlated with and predicted by their memory performance. We then examined the neuroanatomical correlates of pause frequency in the AD participants. Considering the PBN, pause frequency was also positively correlated with the grey matter density of the anterior temporal lobe. These findings suggest that patients use pauses as compensatory mechanisms in the earliest stages of AD. Pauses therefore may reflect the time required for the compensation and the realisation of a weak process depending on the narrative task and should be considered as a positive sign.
词汇语义障碍是阿尔茨海默病（AD）的最早症状之一，通常通过单个单词处理任务进行检查。在言语产生过程中，停顿通常被视为患者词汇语义下降的标志。在当前的研究中，我们提出了一个假设，即停顿根据话语类型反映不同的过程。我们认为，词汇和语义障碍会预测基于图片的叙述（PBN）中患者的停顿频率，而顺行记忆会预测基于记忆的叙述（MBN）中患者的停顿频率。为了证明这一点，我们招募了 17 名早期 AD 患者和 17 名匹配的对照者。他们接受了全面的神经心理学和语言评估以及两项叙事产生评估。我们比较了 AD 参与者和健康对照组在 PBN 和 MBN 中的停顿持续时间和频率。在每个叙述中以及在每个组中都使用多元回归模型来评估认知过程与停顿频率之间的关系。我们的结果表明，只有 AD 参与者在 PBN 中产生了更多的停顿。频率与语义流畅性表现呈正相关，与预期相反。在 MBN 中，AD 参与者的停顿频率与他们的记忆表现呈正相关，并可以预测。然后，我们检查了 AD 参与者中停顿频率的神经解剖学相关性。考虑到 PBN，停顿频率也与前颞叶灰质密度呈正相关。这些发现表明，患者在 AD 的早期阶段使用停顿作为补偿机制。因此，停顿可能反映了根据叙事任务补偿和实现弱过程所需的时间，并且应该被视为一个积极的迹象。
