The cognitive and neural expression of semantic memory impairment in mild cognitive impairment and early Alzheimer's disease

Département de psychologie et CERNEC, Université de Montréal, Montreal, Québec, Canada.
Neuropsychologia (Impact Factor: 3.3). 11/2009; 48(4):978-88. DOI: 10.1016/j.neuropsychologia.2009.11.019
Source: PubMed


Semantic deficits in Alzheimer's disease have been widely documented, but little is known about the integrity of semantic memory in the prodromal stage of the illness. The aims of the present study were to: (i) investigate naming abilities and semantic memory in amnestic mild cognitive impairment (aMCI), early Alzheimer's disease (AD) compared to healthy older subjects; (ii) investigate the association between naming and semantic knowledge in aMCI and AD; (iii) examine if the semantic impairment was present in different modalities; and (iv) study the relationship between semantic performance and grey matter volume using voxel-based morphometry. Results indicate that both naming and semantic knowledge of objects and famous people were impaired in aMCI and early AD groups, when compared to healthy age- and education-matched controls. Item-by-item analyses showed that anomia in aMCI and early AD was significantly associated with underlying semantic knowledge of famous people but not with semantic knowledge of objects. Moreover, semantic knowledge of the same concepts was impaired in both the visual and the verbal modalities. Finally, voxel-based morphometry analyses revealed that semantic impairment in aMCI and AD was associated with cortical atrophy in the anterior temporal lobe (ATL) region as well as in the inferior prefrontal cortex (IPC), some of the key regions of the semantic cognition network. These findings suggest that the semantic impairment in aMCI may result from a breakdown of semantic knowledge of famous people and objects, combined with difficulties in the selection, manipulation and retrieval of this knowledge.


Available from: Olivier Felician
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    • "Similarly, the semantic network is globally left-lateralized for visually-presented verbal material whereas auditory stimuli often recruit bilateral structures (Marinkovic, 2004). While we can assume that regions implicated in semantic control system may be amodal, specific subregions within this network may be recruited differently, depending on the type of conceptual knowledge required to be processed, on the nature of the input or on the nature of the task demands (Brambati, Benoit, Monetta, Belleville, & Joubert, 2010). In the same line, we can't exclude the possibility that some age-related differences of activation might be related to other cognitive processes, such as attentional processes . "
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    ABSTRACT: Semantic memory recruits an extensive neural network including the left inferior prefrontal cortex (IPC) and the left temporoparietal region, which are involved in semantic control processes, as well as the anterior temporal lobe region (ATL) which is considered to be involved in processing semantic information at a central level. However, little is known about the underlying neuronal integrity of the semantic network in normal aging. Young and older healthy adults carried out a semantic judgment task while their cortical activity was recorded using magnetoencephalography (MEG). Despite equivalent behavioral performance, young adults activated the left IPC to a greater extent than older adults, while the latter group recruited the temporoparietal region bilaterally and the left ATL to a greater extent than younger adults. Results indicate that significant neuronal changes occur in normal aging, mainly in regions underlying semantic control processes, despite an apparent stability in performance at the behavioral level. Copyright © 2015 Elsevier Inc. All rights reserved.
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    • "For instance, the alteration of the nervous system in Alzheimer's disease (AD) causes significant decline in touch (Stephen et al., 2010), audition (Gates et al., 2011), vision (Kirby et al., 2010), and so forth. Yet, basic perception tasks such as detection of visual features (e.g., orientation, colors, etc.) and perceptual priming tasks remain preserved (Fleischman et al., 2005; Joubert et al., 2010). Motor and movement disorders are also very common in neurocognitive disorders, especially in Parkinson Disease (PD, Beitz, 2014) and Lewy body's dementia (Molano, 2013). "
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    • "significant impairment or disruption in SM (Chertkow & Bub, 1990), as well as MCI (Adlam, Bozeat, Arnold, Watson, & Hodges, 2006). In MCI, the incidence of SM deficits is about 50% of all the cases (Ahmed et al., 2008; Hodges, Salmon, & Butters, 1992; Joubert et al., 2010; but see Adlam et al., 2006; Balthazar, Cendes, & Damasceno, 2008; Clague, Graham, Thompson, & Hodges, 2011 "
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