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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: 3.45). 11/2009; 48(4):978-88. DOI: 10.1016/j.neuropsychologia.2009.11.019
Source: PubMed

ABSTRACT 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.

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Available from: Olivier Felician, Aug 21, 2015
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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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    • "Naming deficits are not prominent in aMCI, who may have mild, subclinical naming disorders. Deficits in naming objects are in fact an uncommon finding (Balthazar et al., 2008; Clague et al., 2011; Adlam et al., 2006; Choi et al., 2013; Gardini et al., 2013; but see Joubert et al., 2010 and Ahmed et al., 2008), while naming pictures of unique entities including famous people, famous buildings and famous public events seems to be more consistently affected (Joubert et al., 2010; Gardini et al., 2013; Ahmed et al., 2008; Estévez-González et al., 2004; Clague et al., 2011). On the other hand, disease progression is associated with semantic memory dysfunction, and there is some evidence that subtle semantic deficits (semantic fluency) are a predictor of progression towards dementia (Gainotti et al., 2014). "
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