Phonological Blocking During Picture Naming in Dementia of the Alzheimer Type

Learning From Mistakes: Cognitive and Metabolic Correlates of Errors on Picture Naming in the Alzheimer’s Disease Spectrum

Background: Analysis of subtypes of picture naming errors produced by patients with Alzheimer’s disease (AD) have seldom been investigated yet may clarify the cognitive and neural underpinnings of naming in the AD spectrum. Objective: To elucidate the neurocognitive bases of picture naming in AD through a qualitative analysis of errors. Methods: Over 1000 naming errors produced by 70 patients with amnestic, visuospatial, linguistic, or frontal AD were correlated with general cognitive tests and with distribution of hypometabolism on FDG-PET. Results: Principal component analysis identified 1) a Visual processing factor clustering visuospatial tests and unrecognized stimuli, pure visual errors and visual-semantic errors, associated with right parieto-occipital hypometabolism; 2) a Concept-Lemma factor grouping language tests and anomias, circumlocutions, superordinates, and coordinates, correlated with left basal temporal hypometabolism; 3) a Lemma-Phonology factor including the digit span and phonological errors, linked with left temporo-parietal hypometabolism. Regression of brain metabolism on individual errors showed that errors due to impairment of basic and higher-order processing of object visual attributes or of their interaction with semantics, were related with bilateral occipital and left occipito-temporal dysfunction. Omissions and superordinates were linked to degradation of broad and basic concepts in the left basal temporal cortex. Semantic-lexical errors derived from faulty semantically- and phonologically-driven lexical retrieval in the left superior and middle temporal gyri. Generation of nonwords was underpinned by of phonological impairment within the left inferior parietal cortex. Conclusion: Analysis of individual naming errors allowed to outline a comprehensive anatomo-functional model of picture naming in classical and atypical AD.

A Metabolic Imaging Study of Lexical and Phonological Naming Errors in Alzheimer Disease

Patients with Alzheimer disease (AD) produce a variety of errors on confrontation naming that indicate multiple loci of impairment along the naming process in this disease. We correlated brain hypometabolism, measured with 18fluoro-deoxy-glucose positron emission tomography, with semantic and formal errors, as well as nonwords deriving from phonological errors produced in a picture-naming test by 63 patients with AD. Findings suggest that neurodegeneration leads to: (1) phonemic errors, by interfering with phonological short-term memory, or with control over retrieval of phonological or prearticulatory representations, within the left supramarginal gyrus; (2) semantic errors, by disrupting general semantic or visual-semantic representations at the level of the left posterior middle and inferior occipitotemporal cortex, respectively; (3) formal errors, by damaging the lexical-phonological output interface in the left mid-anterior segment of middle and superior temporal gyri. This topography of semantic-lexical-phonological steps of naming is in substantial agreement with dual-stream neurocognitive models of word generation.

Lexical Retrieval or Semantic Knowledge? Which One Causes Naming Errors in Patients with Mild and Moderate Alzheimer's Disease?

Background

The purpose of the study was to analyze naming errors in patients with Alz­heimer's disease in comparison to healthy subjects and determine the underlying cause of naming errors in these patients.

Method

In this study, we included 35 healthy elderly subjects, 23 patients with mild Alzheimer's disease, and 23 with moderate Alzheimer's disease. Forty-five images were used to determine the type of naming errors, and to identify the underlying cause of errors, matching an image with a written word was used.

Results

Patients with Alz­heimer's disease had more naming errors compared with the group of healthy elderly, and patients with moderate Alzheimer's disease showed a slower reaction in matching an image with a written word.

Conclusion

Anomia in the initial phase of Alzheimer's disease is due to problems in lexical retrieval; however, as the disease advances, in addition to lexical retrieval problems, conceptual knowledge causes naming problems.

Understanding the world of dementia. How do people with dementia experience the world?

BACKGROUND

There is growing awareness that the subjective experience of people with dementia is important for understanding behavior and improving quality of life. This paper reviews and reflects on the currently available theories on subjective experience in dementia and it explores the possibility of a knowledge gap on the influence of neurological deficits on experience in late stage dementia.

METHODS

A literature review on current commonly used theories on experience in dementia was supplemented with a systematic review in PubMed and Psychinfo. For the systematic review, the terms used were Perception and Dementia and Behavior; and Awareness and Dementia and Long term care.

RESULTS

Current models emphasize the psychosocial factors that influence subjective experience, but the consequences of neurological deficits are not elaborated upon. The systematic literature search on the neuropsychological functioning in dementia resulted in 631 papers, of which 94 were selected for review. The current knowledge is limited to the early stages of Alzheimer's disease. Next to memory impairments, perception of the direct environment, interpretation of the environment, and inhibition of own responses to the environment seem to be altered in people with dementia.

CONCLUSIONS

Without knowledge on how perception, interpretation and the ability for response control are altered, the behavior of people with dementia can easily be misinterpreted. Research into neuropsychological functioning of people in more severe stages and different forms of dementia is needed to be able to develop a model that is truly biopsychosocial. The proposed model can be used in such research as a starting point for developing tests and theories.

Impact of auditory-visual bimodality on lexical retrieval in Alzheimer's disease patients

The aim of this study was to generalize the positive impact of auditory-visual bimodality on lexical retrieval in Alzheimer's disease (AD) patients. In practice, the naming skills of healthy elderly persons improve when additional sensory signals are included. The hypothesis of this study was that the same influence would be observable in AD patients. Sixty elderly patients separated into three groups (healthy subjects, stage 1 AD patients, and stage 2 AD patients) were tested with a battery of naming tasks comprising three different modalities: a visual modality, an auditory modality, and a visual and auditory modality (bimodality). Our results reveal the positive influence of bimodality on the accuracy with which bimodal items are named (when compared with unimodal items) and their latency (when compared with unimodal auditory items). These results suggest that multisensory enrichment can improve lexical retrieval in AD patients.

Naming ability in patients with mild to moderate Alzheimer's disease: what changes occur with the evolution of the disease?

OBJECTIVES

Naming deficit is a linguistic symptom that appears in the initial phase of Alzheimer's disease, but the types of naming errors and the ways in which this deficit changes over the course of the disease are unclear. We analyzed the performance of patients with Alzheimer's disease on naming tasks during the mild and moderate phases and verified how this linguistic skill deteriorates over the course of the disease.

METHODS

A reduced version of the Boston Naming Test was administered to 30 patients with mild Alzheimer's disease, 30 patients with moderate Alzheimer's disease and 30 healthy controls. Errors were classified as verbal semantic paraphasia, verbal phonemic paraphasia, no response (pure anomia), circumlocution, unrelated verbal paraphasia, visual errors or intrusion errors.

RESULTS

The patients with moderate Alzheimer's disease had significantly fewer correct answers than did both the control group and the group with mild Alzheimer's disease. With regard to the pattern of errors, verbal semantic paraphasia errors were the most frequent errors in all three groups. Additionally, as the disease severity increased, there was an increase in the number of no-response errors (pure anomia). The group with moderate Alzheimer's disease demonstrated a greater incidence of visual errors and unrelated verbal paraphasias compared with the other two groups and presented a more variable pattern of errors.

CONCLUSIONS

Performance on nominative tasks worsened as the disease progressed in terms of both the quantity and the type of errors encountered. This result reflects impairment at different levels of linguistic processing.

On which abilities are category fluency and letter fluency grounded? A confirmatory factor analysis of 53 Alzheimer's dementia patients

BACKGROUND/AIMS

In Alzheimer's dementia (AD), letter fluency is less impaired than category fluency. To check whether category fluency and letter fluency depend differently on semantics and attention, 53 mild AD patients were given animal and letter fluency tasks, two semantic tests (the Verbal Semantic Questionnaire and the BORB Association Match test), and two attentional tests (the Stroop Colour-Word Interference test and the Digit Cancellation test).

METHODS

We conducted a LISREL confirmatory factor analysis to check the extent to which category fluency and letter fluency tasks were related to semantics and attention, viewed as latent variables.

RESULTS

Both types of fluency tasks were related to the latent variable Semantics but not to the latent variable Attention.

CONCLUSIONS

Our findings warn against interpreting the disproportionate impairment of AD patients on category and letter fluency as a contrast between semantics and attention.

A figurative proverb test for dementia: rapid detection of disinhibition, excuse and confabulation, causing discommunication

BACKGROUND

Communicative disability is regarded as a prominent symptom of demented patients, and many studies have been devoted to analyze deficits of lexical-semantic operations in demented patients. However, it is often observed that even patients with preserved lexical-semantic skills might fail in interactive social communication. Whereas social interaction requires pragmatic language skills, pragmatic language competencies in demented subjects have not been well understood. We propose here a brief stress-free test to detect pragmatic language deficits, focusing on non-literal understanding of figurative expression. We hypothesized that suppression of the literal interpretation was required for figurative language interpretation.

METHODS

 We examined 69 demented subjects, 13 subjects with mild cognitive impairment and 61 healthy controls aged 65 years or more. The subjects were asked the meaning of a familiar proverb categorized as a figurative expression. The answers were analyzed based on five factors, and scored from 0 to 5. To consider the influence of cognitive inhibition on proverb comprehension, the scores of the Stroop Colour-Word Test were compared concerning correct and incorrect answers for each factor, respectively. Furthermore, the characteristics of answers were considered in the light of excuse and confabulation qualitatively.

RESULTS

The proverb comprehension scores gradually decreased significantly as dementia progressed. The literal interpretation of the proverb, which showed difficulties in figurative language comprehension, was related to disinhibition. The qualitative analysis showed that excuse and confabulation increased as the dementia stage progressed.

CONCLUSIONS

Deficits in cognitive inhibition partly explains the difficulties in interactive social communication in dementia. With qualitative analysis, asking the meaning of a proverb can be a brief test applied in a clinical setting to evaluate the stage of dementia, and to illustrate disinhibition, confabulation and excuse, which might cause discommunication and psychosocial maladjustment in demented patients.

Effects of semantic elaboration and typicality on picture naming in Alzheimer disease

PURPOSE

Individuals with probable Alzheimer disease (pAD) are frequently impaired at picture naming. This study examined whether a semantic elaboration task would facilitate naming in pAD, and whether training either semantically typical or atypical stimulus items facilitated generalized improvement in picture naming and category generation tasks.

METHODS

Twelve adults with mild-moderate pAD participated in the study. Participants performed an experimental semantic elaboration training task using a subset of typical items from one category and atypical items from another category. The third category, acted as a control (i.e., no items were trained). The study assessed change in category generation and a picture naming within the three target categories.

RESULTS

Individuals showed significantly improved category generation and naming, but changes were not limited to trained categories. Naming of trained atypical items improved significantly. Participants showed significantly improved naming of untrained typical items from categories trained with typical items.

CONCLUSIONS

Semantic elaboration of typical items within a semantic category can lead to generalized improvement in other typical items in the category in mild-moderate pAD. This is consistent with theories postulating that typical category items share overlapping distributed representations. Further exploration of the effects of semantic elaboration on word-finding in pAD is warranted, especially the possibility of within-category generalization.

Coordinated and circumlocutory semantic naming errors are related to anterolateral temporal lobes in mild AD, amnestic mild cognitive impairment, and normal aging

Naming difficulties are characteristic of Alzheimer's disease (AD) and, to a lesser extent, of amnestic mild cognitive impairment (aMCI) patients. The association of naming impairment with anterior temporal lobe (ATL) atrophy in Semantic Dementia (SD) could be a tip of the iceberg effect, in which case the atrophy is a marker of more generalized temporal lobe pathology. Alternatively, it could reflect the existence of a functional gradient within the temporal lobes, wherein more anterior regions provide the basis for greater specificity of representation. We tested these two hypotheses in a study of 15 subjects with mild AD, 17 with aMCI, and 16 aged control subjects and showed that coordinate and circumlocutory semantic error production on the Boston Naming Test was weakly correlated with ATL gray matter density, as determined by voxel-based morphometry. Additionally, we investigated whether these errors were benefited by phonemic cues, and similarly to SD, our AD patients had small improvement. Because there is minimal gradient of temporal lobe atrophy in AD or MCI, and, therefore, no basis for a tip of the iceberg effect, these findings support the theory of a modest functional gradient in the temporal lobes, with the ATLs being involved in the naming of more specific objects.

Learning and forgetting new names and objects in MCI and AD

We studied how subjects with mild cognitive impairment (MCI), early Alzheimer's disease (AD) and age-matched controls learned and maintained the names of unfamiliar objects that were trained with or without semantic support (object definitions). Naming performance, phonological cueing, incidental learning of the definitions and recognition of the objects were tested during follow-up. We found that word learning was significantly impaired in MCI and AD patients, whereas forgetting patterns were similar across groups. Semantic support showed a beneficial effect on object name retrieval in the MCI group 8 weeks after training, suggesting that the MCI patients' preserved semantic memory can compensate for impaired episodic memory. The MCI group performed equally well as the controls in the tasks measuring incidental learning and recognition memory, whereas the AD group showed impairment in this respect. Both the MCI and the AD group benefited less from phonological cueing than the controls. Our findings indicate that word learning is compromised in both MCI and AD, whereas long-term retention of newly learned words is not affected to the same extent. Incidental learning and recognition memory seem to be well preserved in MCI.

Subclinical naming errors in mild cognitive impairment: A semantic deficit?

Mild cognitive impairment (MCI) is the transitional stage between normal aging and Alzheimer’s disease (AD). Impairments in semantic memory have been demonstrated to be a critical factor in early AD. The Boston Naming Test (BNT) is a straightforward method of examining semantic or visuo-perceptual processing and therefore represents a potential diagnostic tool. The objective of this study was to examine naming ability and identify error types in patients with amnestic mild cognitive impairment (aMCI).

Exploring the dynamics of aphasic word production using the picture-word interference task: a case study

In this study, we use an auditory picture-word interference task to examine an anomic individual, NP. NP produced semantic errors in picture naming, but his comprehension was relatively well preserved. In the task, pictures to be named were accompanied by semantically, phonologically or unrelated distractors, presented at onsets ranging from -200ms (before target) to +400ms (after target). Naming latencies were measured. A group of 12 older controls showed semantic interference (slower latencies with semantic than with unrelated distractors), which was significant at -200ms, and steadily diminished across later onsets. In contrast, at 0ms, NP showed powerful semantic facilitation. There were no significant semantic effects at other onsets, but the trends, particularly at later onsets, were towards interference. Phonological effects for NP were in the same direction as for controls (facilitation) but were of greater magnitude. Indeed, NP showed a reliable facilitatory effect at 0ms (and trends at -200ms and +200ms), but a similar trend in controls failed to reach significance. Within recent models of this task, in which semantic facilitation effects are attributed to an early, pre-lexical semantic processing stage, NP's pattern indicates that semantic processing is abnormally prolonged. The phonological facilitation effects are also consistent with this interpretation. We discuss their implications and future applications of the task to aphasia.