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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    ABSTRACT: Embodiment is revolutionizing the way we consider cognition by incorporating the influence of our body and of the current context within cognitive processing. A growing number of studies which support this view of cognition in young adults stands in stark contrast with the lack of evidence in favor of this view in the field of normal aging and neurocognitive disorders. Nonetheless, the validation of embodiment assumptions on the whole spectrum of cognition is a mandatory step in order for embodied cognition theories to become theories of human cognition. More pragmatically, aging populations represent a perfect target to test embodied cognition theories due to concomitant changes in sensory, motor and cognitive functioning that occur in aging, since these theories predict direct interactions between them. Finally, the new perspectives on cognition provided by these theories might also open new research avenues and new clinical applications in the field of aging. The present article aims at showing the value and interest to explore embodiment in normal and abnormal aging as well as introducing some potential theoretical and clinical applications.
    Frontiers in Psychology 04/2015; 6:463. DOI:10.3389/fpsyg.2015.00463 · 2.80 Impact Factor
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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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    ABSTRACT: In this study, the Nombela 2.0 semantic battery is presented. This is a new version of its earlier precedent: the battery Nombela (I), in an attempt to improve it (dealing with ceiling effects) and reducing the application time by decreasing the number of tasks. The battery is constructed on a common set of 98 stimuli, including both living and nonliving semantic domains. It consists of five tasks designed to explore category specificity by tapping semantic production and comprehension, using both visual and verbal input. All of the items were rated according to Spanish norms, as stated in a previous study of our group, and all of the tasks were matched across domain on six nuisance variables. The present study has two goals: (i) to make available the updated version (2.0) of the Nombela semantic memory battery and (ii) to characterize and compare the neuropsychological profiles of two different patient groups: mild cognitive impairment and Alzheimer disease, with regard to normal controls.
    Neurocase 02/2015; DOI:10.1080/13554794.2015.1006644 · 1.38 Impact Factor
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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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    ABSTRACT: Naming abilities are typically preserved in amnestic Mild Cognitive Impairment (aMCI), a condition associated with increased risk of progression to Alzheimer's disease (AD). We compared the functional correlates of covert picture naming and word reading between a group of aMCI subjects and matched controls. Unimpaired picture naming performance was associated with more extensive activations, in particular involving the parietal lobes, in the aMCI group. In addition, in the condition associated with higher processing demands (blocks of categorically homogeneous items, living items), increased activity was observed in the aMCI group, in particular in the left fusiform gyrus. Graph analysis provided further evidence of increased modularity and reduced integration for the homogenous sets in the aMCI group. The functional modifications associated with preserved performance may reflect, in the case of more demanding tasks, compensatory mechanisms for the subclinical involvement of semantic processing areas by AD pathology.
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