scholarly journals Semantic Processing in Healthy Aging and Alzheimer’s Disease: A Systematic Review of the N400 Differences

2020 ◽  
Vol 10 (11) ◽  
pp. 770
Author(s):  
Marilyne Joyal ◽  
Charles Groleau ◽  
Clara Bouchard ◽  
Maximiliano A. Wilson ◽  
Shirley Fecteau
Keyword(s):  
Systematic Review ◽  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Semantic Processing ◽  
Healthy Aging ◽  
Semantic Knowledge ◽  
Event Related Potential ◽  
N400 Effect ◽  
Pathological Aging ◽  
Healthy Elderly

Semantic deficits are common in individuals with Alzheimer’s disease (AD). These deficits notably impact the ability to understand words. In healthy aging, semantic knowledge increases but semantic processing (i.e., the ability to use this knowledge) may be impaired. This systematic review aimed to investigate semantic processing in healthy aging and AD through behavioral responses and the N400 brain event-related potential. The results of the quantitative and qualitative analyses suggested an overall decrease in accuracy and increase in response times in healthy elderly as compared to young adults, as well as in individuals with AD as compared to age-matched controls. The influence of semantic association, as measured by N400 effect amplitudes, appears smaller in healthy aging and even more so in AD patients. Thus, semantic processing differences may occur in both healthy and pathological aging. The establishment of norms of healthy aging for these outcomes that vary between normal and pathological aging could eventually help early detection of AD.

Semantic Processing of Spoken Words in Alzheimer's Disease: An Electrophysiological Study

1998 ◽  
Vol 10 (3) ◽  
pp. 408-420 ◽  
Author(s):  
Antti Revonsuo ◽  
Raija Portin ◽  
Kirsi Juottonen ◽  
Juha O. Rinne
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Semantic Processing ◽  
Electrophysiological Study ◽  
Semantic Knowledge ◽  
Lexical Selection ◽  
Semantic Representations ◽  
Late Positive Component ◽  
Healthy Elderly ◽  
Spoken Words

Patients suffering from Alzheimer's disease (AD) have severe difficulties in tasks requiring the use of semantic knowledge. The semantic deficits associated with AD have been extensively studied by using behavioral methods. Many of these studies indicate that AD patients have a general deficit in voluntary access to semantic representations but that the structure of the representations themselves might be preserved. However, several studies also provide evidence that to some extent semantic representations in AD may in fact be degraded. Recently, a few studies have utilized event-related brain potentials (ERPs) that are sensitive to semantic factors in order to investigate the electrophysiological correlates of the semantic impairment in AD. Interest has focused on the N400 component, which is known to reºect the on-line semantic processing of linguistic and pictorial stimuli. The results from studies of N400 changes in AD remain somewhat controversial: Some studies report normal or enlarged N400 components in AD, whereas others report diminished ones. One issue not reported in previous studies is whether word-elicited ERPs other than N400 remain normal in AD. In the present study our aim was to find out whether the ERP waveforms N1, P2, N400, and Late Positive Component (LPC) to semantically congruous and incongruous spoken words are abnormal in AD and whether such abnormalities specifically reºect deficiencies in semantic activation in AD. Auditory ERPs from 20 scalp sites to semantically congruous and incongruous final words in spoken sentences were recorded from 17 healthy elderly adults and 9 AD patients. The early ERP waveforms N1 and P2 were relatively normal for the AD patients, but the N400 and LPC effects (amplitude difference between congruous and incongruous conditions) were significantly reduced. We interpret the present results as showing that semantic-conceptual activation and other high-level integration processes are defective in AD. However, a word congruity effect earlier than N400 (phonological mismatch negativity), reflecting lexical selection processes, is at least to some extent preserved in AD.

scholarly journals Smell and taste recognition in early stages of late-onset Alzheimer’s disease

SURG Journal ◽  
2010 ◽  
Vol 4 (1) ◽  
pp. 57-64 ◽  
Author(s):  
Nila Ilhamto ◽  
Lisa M Duizer
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Health Status ◽  
Healthy Aging ◽  
Late Onset ◽  
Word Recall ◽  
Early Stages ◽  
Predictive Variables ◽  
Healthy Elderly ◽  
Inadequate Nutrition

Problems of inadequate nutrition and energy intake are common in the aging population. Smell and taste deficits associated with Late-Onset Alzheimer’s Disease (LOAD) may accentuate the decline in nutritional status of elderly individuals and indirectly enhance progression of cognitive problems in LOAD. The objective of this study was to explore and characterize smell and taste recognition abilities in early stages of LOAD, beyond that of normal healthy aging. A total of 29 healthy-younger subjects aged 18-40 (HY), 13 healthy-elderly (HA) and six elderly adults diagnosed with LOAD (AD) aged 60-85, were recruited from the Guelph community. The Sniffin’ Sticks Screening Test (SSST) and Taste Strips were used to test olfactory and gustatory functions, respectively. Participants also completed the mini-mental state examination (MMSE), clock test and word recall tests to assess cognitive/memory skills. Compared to HA individuals, people with AD had significant odour recognition impairment. Correlation analysis also revealed an age-associated decline in overall taste ability. When specific tastes were examined, impairments in sour and bitter identification were observed with increasing age. However, no significant differences in specific taste abilities were found between HA and AD individuals. In predicting health status (ie. presence or absence of LOAD), an assessment of all variables in this study was conducted using Generalized Linear Model (GLM). Results showed that sweet recognition and clock test scores were the best predictive variables of health status. However, this is a preliminary model that needs refinement through further research using more individuals.

scholarly journals Neuroanatomic substrates of semantic memory impairment in Alzheimer's disease: Patterns of functional MRI activation

1999 ◽  
Vol 5 (5) ◽  
pp. 377-392 ◽  
Author(s):  
ANDREW J. SAYKIN ◽  
LAURA A. FLASHMAN ◽  
SALLY A. FRUTIGER ◽  
STERLING C. JOHNSON ◽  
ALEXANDER C. MAMOURIAN ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Functional Mri ◽  
Semantic Processing ◽  
Superior Temporal Gyrus ◽  
Semantic Networks ◽  
Healthy Elderly ◽  
Disease Patterns ◽  
Dorsolateral Prefrontal ◽  
Significant Performance

Impairment in semantic processing occurs early in Alzheimer's disease (AD) and differential impact on subtypes of semantic relations have been reported, yet there is little data on the neuroanatomic basis of these deficits. Patients with mild AD and healthy controls underwent 3 functional MRI auditory stimulation tasks requiring semantic or phonological decisions (match–mismatch) about word pairs (category–exemplar, category–function, pseudoword). Patients showed a significant performance deficit only on the exemplar task. On voxel-based fMRI activation analyses, controls showed a clear activation focus in the left superior temporal gyrus for the phonological task; patients showed additional foci in the left dorsolateral prefrontal and bilateral cingulate areas. On the semantic tasks, predominant activation foci were seen in the inferior and middle frontal gyrus (left greater than right) in both groups but patients showed additional activation suggesting compensatory recruitment of locally expanded foci and remote regions, for example, right frontal activation during the exemplar task. Covariance analyses indicated that exemplar task performance was strongly related to signal increase in bilateral medial prefrontal cortex. The authors conclude that fMRI can reveal similarities and differences in functional neuroanatomical processing of semantic and phonological information in mild AD compared to healthy elderly, and can help to bridge cognitive and neural investigations of the integrity of semantic networks in AD. (JINS, 1999, 5, 377–392.)

scholarly journals Lexical Retrieval or Semantic Knowledge Which One Causes Naming Errors in Patients with Mild and Moderate Alzheimer’s Disease

2017 ◽  
Vol 7 (3) ◽  
pp. 419-429 ◽  
Author(s):  
Masoome Salehi ◽  
Mohsen Reisi ◽  
Leila Ghasisin
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Healthy Subjects ◽  
Conceptual Knowledge ◽  
Semantic Knowledge ◽  
Elderly Subjects ◽  
Lexical Retrieval ◽  
Healthy Elderly ◽  
Written Word ◽  
Healthy Elderly Subjects

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.

scholarly journals Preserved Extra-Foveal Processing of Object Semantics in Alzheimer’s Disease

2021 ◽  
pp. 089198872110160
Author(s):  
Francesco Cimminella ◽  
Giorgia D’Innocenzo ◽  
Sergio Della Sala ◽  
Alessandro Iavarone ◽  
Caterina Musella ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Object Recognition ◽  
Visual Search ◽  
Eye Tracking ◽  
Semantic Processing ◽  
Semantic Information ◽  
Semantic Knowledge ◽  
Target Object ◽  
Foveal Vision

Alzheimer’s disease (AD) patients underperform on a range of tasks requiring semantic processing, but it is unclear whether this impairment is due to a generalised loss of semantic knowledge or to issues in accessing and selecting such information from memory. The objective of this eye-tracking visual search study was to determine whether semantic expectancy mechanisms known to support object recognition in healthy adults are preserved in AD patients. Furthermore, as AD patients are often reported to be impaired in accessing information in extra-foveal vision, we investigated whether that was also the case in our study. Twenty AD patients and 20 age-matched controls searched for a target object among an array of distractors presented extra-foveally. The distractors were either semantically related or unrelated to the target (e.g., a car in an array with other vehicles or kitchen items). Results showed that semantically related objects were detected with more difficulty than semantically unrelated objects by both groups, but more markedly by the AD group. Participants looked earlier and for longer at the critical objects when these were semantically unrelated to the distractors. Our findings show that AD patients can process the semantics of objects and access it in extra-foveal vision. This suggests that their impairments in semantic processing may reflect difficulties in accessing semantic information rather than a generalised loss of semantic memory.

scholarly journals Investigating Auditory Electrophysiological Measures of Participants with Mild Cognitive Impairment and Alzheimer’s Disease: A Systematic Review and Meta-Analysis of Event-Related Potential Studies

2021 ◽  
pp. 1-30
Author(s):  
Hadeel Y. Tarawneh ◽  
Wilhelmina H.A.M. Mulders ◽  
Hamid R. Sohrabi ◽  
Ralph N. Martins ◽  
Dona M.P. Jayakody
Keyword(s):  
Systematic Review ◽  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Meta Analysis ◽  
Pooled Analysis ◽  
Event Related Potential ◽  
P300 Amplitude ◽  
Related Potentials

Background: Objectively measuring auditory functions has been proposed as an avenue in differentiating normal age-related cognitive dysfunction from Alzheimer’s disease (AD) and its prodromal states. Previous research has suggested auditory event-related potentials (AERPs) to be non-invasive, cost-effective, and efficient biomarkers for the diagnosis of AD. Objective: The objective of this paper is to review the published literature on AERPs measures in older adults diagnosed with AD and those at higher risk of developing AD, i.e., mild cognitive impairment (MCI) and subjective cognitive decline. Methods: The search was performed on six major electronic databases (Ovid MEDLINE, OVID EMBASE, PsycINFO, PubMed, Scopus, and CINAHL Plus). Articles identified prior to 7 May 2019 were considered for this review. A random effects meta-analysis and analysis of between study heterogeneity was conducted using the Comprehensive Meta-Analysis software. Results: The search identified 1,076 articles; 74 articles met the full inclusion criteria and were included in the systematic review, and 47 articles were included into the analyses. Pooled analysis suggests that AD participants can be differentiated from controls due to significant delays in ABR, N100, P200, N200, and P300 latencies. P300 amplitude was significantly smaller in AD participants compared to controls. P300 latencies differed significantly between MCI participants and controls based on the pooled analysis. Conclusion: The findings of this review indicate that some AERPs may be valuable biomarkers of AD. In conjunction with currently available clinical and neuropsychological assessments, AERPs can aid in screening and diagnosis of prodromal AD.

Lexical and Semantic Processing in Healthy Aging and Early Stage Alzheimer's Disease

2012 ◽  
Author(s):  
Andrew J. Aschenbrenner ◽  
David A. Balota ◽  
Chi-Shing Tse ◽  
Melvin J. Yap ◽  
Roger Ratcliff
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Semantic Processing ◽  
Healthy Aging ◽  
Early Stage

scholarly journals Do Alzheimer’s Disease Patients Benefit From Prior-Knowledge in Associative Recognition Memory?

2019 ◽  
Vol 25 (04) ◽  
pp. 443-452
Author(s):  
Emma Delhaye ◽  
Adrien Folville ◽  
Isabelle Simoes Loureiro ◽  
Laurent Lefebvre ◽  
Eric Salmon ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Older Adults ◽  
Alzheimer's Disease ◽  
Prior Knowledge ◽  
Semantic Memory ◽  
Associative Memory ◽  
Healthy Aging ◽  
Memory Task ◽  
Semantic Knowledge ◽  
Healthy Older Adults

AbstractObjectives: Although the influence of prior knowledge on associative memory in healthy aging has received great attention, it has never been studied in Alzheimer’s disease (AD). This study aimed at assessing whether AD patients could benefit from prior knowledge in associative memory and whether such benefit would be related to the integrity of their semantic memory. Methods: Twenty-one AD patients and 21 healthy older adults took part in an associative memory task using semantically related and unrelated word pairs and were also submitted to an evaluation of their semantic memory. Results: While participants of both groups benefited from semantic relatedness in associative discrimination, related pairs recognition was significantly predicted by semantic memory integrity in healthy older adults only. Conclusions: We suggest that patients benefitted from semantic knowledge to improve their performance in the associative memory task, but that such performance is not related to semantic knowledge integrity evaluation measures because the two tasks differ in the way semantic information is accessed: in an automatic manner for the associative memory task, with automatic processes thought to be relatively preserved in AD, and in a controlled manner for the semantic knowledge evaluation, with controlled processes thought to be impaired in AD. (JINS, 2019, 25, 443–452)

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