Cognitive resources during sentence processing in Alzheimer's disease

The Role of Working Memory and Short-Term Memory in Sentence Comprehension: A Systematic Review and Meta-Analysis in Probable Alzheimer's Disease

The role of either short-term memory (STM) or working memory (WM) in sentence comprehension is a matter of debate. Although it is commonly accepted that memory resources are necessary for sentence comprehension, there is no agreement regarding the nature of their role. The aim of this review is to investigate and synthesize assessment tools and correlation data between STM or WM and sentence comprehension in probable Alzheimer's disease (AD). To this aim, a systematic review and meta-analysis of the literature was conducted according to the PRISMA guidelines. PubMed, Web of Science, Scopus, PsycInfo, and LLBA databases were searched. Two independent authors selected peer-reviewed articles published in English and focused on the relationship between STM or WM and sentence comprehension in probable AD. A total of 11 case-control studies were included at the end of the selection process. Most studies adopted offline tasks to evaluate sentence comprehension, while a small number of authors applied online experimental tasks. The digit span forward and backward were the most employed standardized tests to evaluate phonological STM and WM, respectively. The meta-analysis results supported the association between performance on STM and WM and comprehension tasks. However, moderate heterogeneity was found, mainly due to the small number of included studies, especially for STM, and the substantial variability of the adopted tasks. Therefore, in order to clarify the specific source of language comprehension deficits, new and sophisticated experiments should be conducted using adequate material.

Universal and Language-Specific Connected Speech Characteristics of Bilingual Speakers With Alzheimer's Disease: Insights From Case Studies of Structurally Distinct Languages

PURPOSE

Connected speech analysis has been effectively utilized for the diagnosis and disease monitoring of individuals with Alzheimer's disease (AD). Existing research has been conducted mostly in monolingual English speakers with a noticeable lack of evidence from bilinguals and non-English speakers, particularly in non-European languages. Using a case study approach, we characterized connected speech profiles of two Bengali-English bilingual speakers with AD to determine the universal features of language impairments in both languages, identify language-specific differences between the languages, and explore language impairment characteristics of the participants with AD in relation to their bilingual language experience.

METHOD

Participants included two Bengali-English bilingual speakers with AD and a group of age-, gender-, education-, and language-matched neurologically healthy controls. Connected speech samples were collected in first language (L1; Bengali) and second language (L2; English) using a novel storytelling task (i.e., Frog, Where Are You?). These samples were analyzed using an augmented quantitative production analysis and correct information unit analyses for productivity, fluency, syntactic and morphosyntactic features, and lexical and semantic characteristics.

RESULTS

Irrespective of the language, AD impacted speech productivity (speech rate and fluency) and semantic characteristics in both languages. Unique language-specific differences were noted on syntactic measures (reduced sentence length in Bengali), lexical distribution (fewer pronouns and absence of reduplication in Bengali), and inflectional properties (no difficulties with noun or verb inflections in Bengali). Among the two participants with AD, the individual who showed lower proficiency and usage in L2 (English) demonstrated reduced syntactic complexity and morphosyntactic richness in English.

CONCLUSIONS

Evidence from these case studies suggests that language impairment features in AD are not universal across languages, particularly in comparison to impairments typically associated with language breakdowns in English. This study underscores the importance of establishing connected speech profiles in AD for non-English-speaking populations, especially for structurally different languages. This would in turn lead to the development of language-specific markers that can facilitate early detection of language deterioration and aid in improving diagnosis of AD in individuals belonging to underserved linguistically diverse populations.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.25412458.

Methodologies for assessing morphosyntactic ability in people with Alzheimer's disease

BACKGROUND

The detection and description of language impairments in neurodegenerative diseases like Alzheimer's Disease (AD) play an important role in research, clinical diagnosis and intervention. Various methodological protocols have been implemented for the assessment of morphosyntactic abilities in AD; narrative discourse elicitation tasks and structured experimental tasks for production, offline and online structured experimental tasks for comprehension. Very few studies implement and compare different methodological protocols; thus, little is known about the advantages and disadvantages of each methodology.

AIMS

To discuss and compare the main behavioral methodological approaches and tasks that have been used in psycholinguistic research to assess different aspects of morphosyntactic production and comprehension in individuals with AD at the word and sentence levels.

METHODS

A narrative review was conducted through searches in the scientific databases Google Scholar, Scopus, Science Direct, MITCogNet, PubMed. Only studies written in English, that reported quantitative data and were published in peer-reviewed journals were considered with respect to their methodological protocol. Moreover, we considered studies that reported research on all stages of the disease and we included only studies that also reported results of a healthy control group. Studies that implemented standardized assessment tools were not considered in this review.

OUTCOMES & RESULTS

The main narrative discourse elicitation tasks implemented for the assessment of morphosyntactic production include interviews, picture-description and story narration, whereas the main structured experimental tasks include sentence completion, constrained sentence production, sentence repetition and naming. Morphosyntactic comprehension in AD has been assessed with the use of structured experimental tasks, both offline (sentence-picture matching, grammaticality judgment) and online (cross-modal naming,speeded sentence acceptability judgment, auditory moving window, word detection, reading). For each task we considered studies that reported results from different morphosyntactic structures and phenomena in as many different languages as possible.

CONCLUSIONS & IMPLICATIONS

Our review revealed strengths and weaknesses of these methods but also directions for future research. Narrative discourse elicitation tasks as well as structured experimental tasks have been used in a variety of languages, and have uncovered preserved morphosyntactic production but also deficits in people with AD. A combination of narrative discourse elicitation and structured production tasks for the assessment of the same morphosyntactic structure has been rarely used. Regarding comprehension, offline tasks have been implemented in various languages, whereas online tasks have been mainly used in English. Offline and online experimental paradigms have often produced contradictory results even within the same study. The discrepancy between the two paradigms has been attributed to the different working memory demands they impose to the comprehender or to the different parsing processes they tap. Strengths and shortcomings of each methodology are summarized in the paper, and comparisons between different tasks are attempted when this is possible. Thus, the paper may serve as a methodological guide for the study of morphosyntax in AD and possibly in other neurodegenerative diseases.

WHAT THIS PAPER ADDS

What is already known on this subject For the assessment of morphosyntactic abilities in AD, various methodological paradigms have been implemented: narrative discourse elicitation tasks and structured experimental tasks for production, and offline and online structured experimental tasks for comprehension. Very few studies implement and compare different methodological protocols; thus, little is known about the advantages and disadvantages of each methodology. What this paper adds to existing knowledge The paper presents an overview of methodologies that have been used to assess morphosyntactic production and comprehension of people with AD at the word and sentence levels. The paper summarizes the strengths and shortcomings of each methodology, providing both the researcher and the clinician with some directions in their endeavour of investigating language in AD. Also, the paper highlights the need for further research that will implement carefully scrutinized tasks from various experimental paradigms and will explore distinct aspects of the AD patients' morphosyntactic abilities in typologically different languages. What are the potential or actual clinical implications of this work? The paper may serve as a reference point for (psycho-)linguists who wish to study morphosyntactic abilities in AD, and for speech and language therapists who might need to apply morphosyntactic protocols to their patients in order to assess them or design appropriate therapeutic interventions for production and comprehension deficits.

Investigating sentence processing and working memory in patients with mild Alzheimer and elderly people

INTRODUCTION

Linguistic disorders are one of the common problems in Alzheimer's disease, which in recent years has been considered as one of the key parameters in the diagnosis of Alzheimer (AD). Given that changes in sentence processing and working memory and the relationship between these two activities may be a diagnostic parameter in the early and preclinical stages of AD, the present study examines the comprehension and production of sentences and working memory in AD patients and healthy aged people.

METHODS

Twenty-five people with mild Alzheimer's and 25 healthy elderly people participated in the study. In this study, we used the digit span to evaluate working memory. Syntactic priming and sentence completion tasks in canonical and non-canonical conditions were used for evaluating sentence production. We administered sentence picture matching and cross-modal naming tasks to assess sentence comprehension.

RESULTS

The results of the present study revealed that healthy elderly people and patients with mild Alzheimer's disease have a significant difference in comprehension of relative clause sentences (P <0.05). There was no significant difference between the two groups in comprehension of simple active, simple active with noun phrase and passive sentences (P> 0.05). They had a significant difference in auditory and visual reaction time (P <0.05). Also there was a significant difference between the two groups in syntactic priming and sentence completion tasks. However, in non-canonical condition of sentence completion, the difference between the two groups was not significant (P> 0.05).

CONCLUSION

The results of the present study showed that the mean scores related to comprehension, production and working memory in people with mild Alzheimer's were lower than healthy aged people, which indicate sentence processing problems at this level of the disease. People with Alzheimer have difficulty comprehending and producing complex syntactic structures and have poorer performance in tasks that required more memory demands. It seems that the processing problems of these people are due to both working memory and language problems, which are not separate from each other and both are involved in.

Language changes in Alzheimer's disease: A systematic review of verb processing

Alzheimer's disease (AD) results in language impairments and higher-level communication problems. Research into the language of people with AD (pwAD) has mainly focused on nouns; however, improved understanding of verb processing by pwAD could improve diagnostic assessments and communicative interventions. This systematic review synthesizes findings of AD's effects on verbs from single-word, sentence, and discourse tasks. Review of 57 studies revealed that pwAD were less accurate than controls on single-word tasks and less accurate with verbs than nouns on these tasks. They had difficulty comprehending sentences featuring multiple verbs or verbs with reversible thematic roles. Discourse production by pwAD was marked by vagueness, including declines in total output and propositional content and a preference for generic verbs and simple syntax. Few studies examining sentence production or discourse comprehension were found. Future research should address relationships between long-term memory and language preservation as well as verb use in discourse.

Neurostimulation Combined With Cognitive Intervention in Alzheimer's Disease (NeuroAD): Study Protocol of Double-Blind, Randomized, Factorial Clinical Trial

Despite advances in the treatment of Alzheimer’s disease (AD), there is currently no prospect of a cure, and evidence shows that multifactorial interventions can benefit patients. A promising therapeutic alternative is the use of transcranial direct current stimulation (tDCS) simultaneously with cognitive intervention. The combination of these non-pharmacological techniques is apparently a safe and accessible approach. This study protocol aims to compare the efficacy of tDCS and cognitive intervention in a double-blind, randomized and factorial clinical trial. One hundred participants diagnosed with mild-stage AD will be randomized to receive both tDCS and cognitive intervention, tDCS, cognitive intervention, or placebo. The treatment will last 8 weeks, with a 12-month follow-up. The primary outcome will be the improvement of global cognitive functions, evaluated by the AD Assessment Scale, cognitive subscale (ADAS-Cog). The secondary outcomes will include measures of functional, affective, and behavioral components, as well as a neurophysiological marker (Brain-derived neurotrophic factor, BDNF). This study will enable us to assess, both in the short and long term, whether tDCS is more effective than the placebo and to examine the effects of combined therapy (tDCS and cognitive intervention) and isolated treatments (tDCS vs. cognitive intervention) on patients with AD.

Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT02772185—May 5, 2016.

Quantitative EEG After Brain Stimulation and Cognitive Training in Alzheimer Disease

PURPOSE

Medications are the currently accepted symptomatic treatment of Alzheimer disease (AD), but their impact on delaying the progression of cognitive deficits and functional impairment is limited. The authors aimed to explore long-term electrophysiological effects of repetitive transcranial magnetic stimulation interlaced with cognitive training on quantitative electroencephalography (EEG) in patients with AD.

METHODS

Quantitative EEG was assessed on non-repetitive transcranial magnetic stimulation interlaced with cognitive training treatment days before treatment and after each treatment phase in seven patients with mild AD.

RESULTS

After 4.5 months (54 sessions) of treatment, a significant increase of delta activity over the temporal region was found compared with pretreatment values. Nonsignificant increases of the log EEG power were found for alpha band over the frontal and temporal regions, beta band over the frontal region, theta band over the frontal, temporal, and parieto-occipital regions, and delta band over the frontal and parieto-occipital regions. Nonsignificant decreases were found for alpha over the parieto-occipital region, and for beta over the temporal and parieto-occipital regions. A positive correlation was found between log alpha power over the frontal and temporal regions at 6 weeks and Mini-Mental State Examination (MMSE) scores at 6 weeks and 4.5 months, and between log alpha power over the parieto-occipital regions and MMSE scores at 6 weeks. A negative correlation was found between log alpha power over the frontal and temporal regions at 6 weeks and baseline Alzheimer's Disease Assessment Scale-cognitive subscale scores.

CONCLUSIONS

Repetitive transcranial magnetic stimulation interlaced with cognitive training has long-term effects on quantitative EEG in patients with mild AD. Further research on the quantitative EEG long-term effects of transcranial magnetic stimulation interlaced with cognitive training is required to confirm the authors' data.

Speech perception in noise in the elderly: interactions between cognitive performance, depressive symptoms, and education

Introduction

Objective

Methods

Results

Conclusion

Variable disruption of a syntactic processing network in primary progressive aphasia

Syntactic processing deficits are highly variable in individuals with primary progressive aphasia. Damage to left inferior frontal cortex has been associated with syntactic deficits in primary progressive aphasia in a number of structural and functional neuroimaging studies. However, a contrasting picture of a broader syntactic network has emerged from neuropsychological studies in other aphasic cohorts, and functional imaging studies in healthy controls. To reconcile these findings, we used functional magnetic resonance imaging to investigate the functional neuroanatomy of syntactic comprehension in 51 individuals with primary progressive aphasia, composed of all clinical variants and a range of degrees of syntactic processing impairment. We used trial-by-trial reaction time as a proxy for syntactic processing load, to determine which regions were modulated by syntactic processing in each patient, and how the set of regions recruited was related to whether syntactic processing was ultimately successful or unsuccessful. Relationships between functional abnormalities and patterns of cortical atrophy were also investigated. We found that the individual degree of syntactic comprehension impairment was predicted by left frontal atrophy, but also by functional disruption of a broader syntactic processing network, comprising left posterior frontal cortex, left posterior temporal cortex, and the left intraparietal sulcus and adjacent regions. These regions were modulated by syntactic processing in healthy controls and in patients with primary progressive aphasia with relatively spared syntax, but they were modulated to a lesser extent or not at all in primary progressive aphasia patients whose syntax was relatively impaired. Our findings suggest that syntactic comprehension deficits in primary progressive aphasia reflect not only structural and functional changes in left frontal cortex, but also disruption of a wider syntactic processing network.

Cue Recognition and Integration - Eye Tracking Evidence of Processing Differences in Sentence Comprehension in Aphasia

Purpose

We aimed at further elucidating whether aphasic patients’ difficulties in understanding non-canonical sentence structures, such as Passive or Object-Verb-Subject sentences, can be attributed to impaired morphosyntactic cue recognition, and to problems in integrating competing interpretations.

Methods

A sentence-picture matching task with canonical and non-canonical spoken sentences was performed using concurrent eye tracking. Accuracy, reaction time, and eye tracking data (fixations) of 50 healthy subjects and 12 aphasic patients were analysed.

Results

Patients showed increased error rates and reaction times, as well as delayed fixation preferences for target pictures in non-canonical sentences. Patients’ fixation patterns differed from healthy controls and revealed deficits in recognizing and immediately integrating morphosyntactic cues.

Conclusion

Our study corroborates the notion that difficulties in understanding syntactically complex sentences are attributable to a processing deficit encompassing delayed and therefore impaired recognition and integration of cues, as well as increased competition between interpretations.

Language Impairment in Adolescents With Sydenham Chorea

BACKGROUND

Neuropsychiatric comorbidities are frequent in Sydenham chorea. However, cognitive impairment in Sydenham chorea has not been sufficiently described. The objective of this study was to evaluate expressive and receptive language deficits in adolescents with Sydenham chorea.

METHODS

Twenty patients with Sydenham chorea were compared with 20 patients with rheumatic fever without chorea and 20 healthy controls. Participants were matched for age and gender. Participants were assessed with verbal fluency tasks (phonemic and semantic) and with verbal comprehension tasks (Token Test). Patients with Sydenham chorea were also assessed with the Universidade Federal de Minas Gerais Sydenham Chorea Rating Scale.

RESULTS

Performance in verbal fluency and in verbal comprehension tasks differed significantly (P < 0.01) among the three groups. Patients with Sydenham chorea performed significantly worse than healthy control group in phonemic and semantic verbal fluency tasks as well as in the Token Test. The group with rheumatic fever also performed worse than healthy controls in phonemic verbal fluency. Severity of motor signs in Sydenham chorea inversely correlated with performance in phonemic verbal fluency (words beginning with letter S, and total sum of words beginning with letters F, A, and S).

CONCLUSIONS

Adolescents with Sydenham chorea show difficulties in verbal fluency and in verbal comprehension. Patients with rheumatic fever also have some degree of language impairment. Future studies must investigate language impairment in difference stages of Sydenham chorea (acute, persistent, and remission) and putative biological markers.

Increased prospective memory interference in normal and pathological aging: different roles of motor and verbal processing speed

This is a study on prospective memory (PM) and the PM interference effect in normal and pathological aging. One hundred and seven subjects, including 41 healthy young adults, 40 non-demented older adults and 26 patients with mild Alzheimer's disease (AD) participated in this study using a laboratory event-based PM task. PM task performance was comparable between the non-demented older and young adults, but impaired in the AD patients. The PM interference effect increased progressively from the healthy young adults, the non-demented older adults, to the AD patients. Path analysis revealed that the possible mechanism mediating the increased PM interference was the slow motor processing speed in normal aging, while it was the slow verbal speed in pathological aging. It is suggested that different neuropsychological mechanisms may underpin the affected performance of PM task in normal and pathological aging.

Anomia as a marker of distinct semantic memory impairments in Alzheimer's disease and semantic dementia

OBJECTIVE

Many neurologically constrained models of semantic memory have been informed by two primary temporal lobe pathologies: Alzheimer's disease (AD) and Semantic Dementia (SD). However, controversy persists regarding the nature of the semantic impairment associated with these patient populations. Some argue that AD presents as a disconnection syndrome in which linguistic impairment reflects difficulties in lexical or perceptual means of semantic access. In contrast, there is a wider consensus that SD reflects loss of core knowledge that underlies word and object meaning. Object naming provides a window into the integrity of semantic knowledge in these two populations.

METHOD

We examined naming accuracy, errors and the correlation of naming ability with neuropsychological measures (semantic ability, executive functioning, and working memory) in a large sample of patients with AD (n = 36) and SD (n = 21).

RESULTS

Naming ability and naming errors differed between groups, as did neuropsychological predictors of naming ability. Despite a similar extent of baseline cognitive impairment, SD patients were more anomic than AD patients.

CONCLUSIONS

These results add to a growing body of literature supporting a dual impairment to semantic content and active semantic processing in AD, and confirm the fundamental deficit in semantic content in SD. We interpret these findings as supporting of a model of semantic memory premised upon dynamic interactivity between the process and content of conceptual knowledge.

Beneficial effect of repetitive transcranial magnetic stimulation combined with cognitive training for the treatment of Alzheimer's disease: a proof of concept study

The current drug treatment for Alzheimer's disease (AD) is only partially and temporary effective. Transcranial magnetic stimulation (TMS) is a non-invasive technique that generates an electric current inducing modulation in cortical excitability. In addition, cognitive training (COG) may improve cognitive functions in AD. Our aim was to treat AD patients combining high-frequency repetitive TMS interlaced with COG (rTMS-COG). Eight patients with probable AD, treated for more than 2 months with cholinesterase inhibitors, were subjected to daily rTMS-COG sessions (5/week) for 6 weeks, followed by maintenance sessions (2/week) for an additional 3 months. Six brain regions, located individually by MRI, were stimulated. COG tasks were developed to fit these regions. Primary objectives were average improvement of Alzheimer Disease Assessment Scale-Cognitive (ADAS-cog) and Clinical Global Impression of Change (CGIC) (after 6 weeks and 4.5 months, compared to baseline). Secondary objectives were average improvement of MMSE, ADAS-ADL, Hamilton Depression Scale (HAMILTON) and Neuropsychiatric Inventory (NPI). One patient abandoned the study after 2 months (severe urinary sepsis). ADAS-cog (average) improved by approximately 4 points after both 6 weeks and 4.5 months of treatment (P < 0.01 and P < 0.05) and CGIC by 1.0 and 1.6 points, respectively. MMSE, ADAS-ADL and HAMILTON improved, but without statistical significance. NPI did not change. No side effects were recorded. In this study, rTMS-COG (provided by Neuronix Ltd., Yokneam, Israel) seems a promising effective and safe modality for AD treatment, possibly as good as cholinesterase inhibitors. A European double blind study is underway.

Hierarchical organization of scripts: converging evidence from FMRI and frontotemporal degeneration

The present study examined the organization of complex familiar activities, known as "scripts" (e.g., "going fishing"). We assessed whether events in a script are processed in a linear-sequential manner or clustered-hierarchical manner, and we evaluated the neural basis for this processing capacity. Converging evidence was obtained from functional neuroimaging in healthy young adults and from behavioral and structural magnetic resonance imaging (MRI) data in patients with focal neurodegenerative disease. In both studies, participants judged the order of consecutive event pairs taken from a script. Event pairs either were clustered together within a script or were from different clusters within the script. Controls judged events more accurately and quickly if taken from the same cluster within a script compared with different clusters, even though all event pairs were consecutive, consistent with the hierarchical organization of a script. Functional magnetic resonance imaging associated this with bilateral inferior frontal activation. Patients with progressive nonfluent aphasia or behavior-variant frontotemporal dementia did not distinguish between event pairs from the same cluster or from different clusters within a script. Structural MRI associated this deficit with significant frontal cortical atrophy. Our findings suggest that frontal cortex contributes to clustering events during script comprehension, underlining the role of frontal cortex in the hierarchical organization of a script.

Processing of wh-questions in a case of posterior cortical atrophy

Posterior cortical atrophy (PCA) is a type of dementia that is characterized by visuo-spatial and memory deficits, dyslexia and dysgraphia, relatively early onset and preserved insight. Language deficits have been reported in some cases of PCA. Using an off-line grammaticality judgement task, processing of wh-questions is investigated in a case of PCA. Other aspects of auditory language are also reported. It is shown that processing of wh-questions is influenced by syntactic structure, a novel finding in this condition. The results are discussed with reference to accounts of wh-questions in aphasia. An uneven profile of other language abilities is reported with deficits in digit span (forward, backward), story retelling ability, comparative questions but intact abilities in following commands, repetition, concept definition, generative naming and discourse comprehension.

[Deficit of access or storage: semantic memory processing in Alzheimer disease]

This study investigates three principal aspects of semantic memory processing in Alzheimer's disease: word finding, knowledge of the specific and generic attributes of concepts. Semantic memory is assessed by a range of verbal and visual tasks differentiated according to their level of complexity. Our hypothesis is that the processing of these types of information is modulated by the degree of effortful processing required by the tasks. The AD patients show more important difficulties on the tasks of high level of complexity. Nevertheless, although their performances improve when the level of complexity decreases, they significantly remain lower than those of the normal older subjects. These results are discussed with regard to the models of semantic memory, with particular reference to the debate in terms of a deficit of access or storage of this system in Alzheimer disease.

Word-finding difficulty: a clinical analysis of the progressive aphasias

The patient with word-finding difficulty presents a common and challenging clinical problem. The complaint of 'word-finding difficulty' covers a wide range of clinical phenomena and may signify any of a number of distinct pathophysiological processes. Although it occurs in a variety of clinical contexts, word-finding difficulty generally presents a diagnostic conundrum when it occurs as a leading or apparently isolated symptom, most often as the harbinger of degenerative disease: the progressive aphasias. Recent advances in the neurobiology of the focal, language-based dementias have transformed our understanding of these processes and the ways in which they breakdown in different diseases, but translation of this knowledge to the bedside is far from straightforward. Speech and language disturbances in the dementias present unique diagnostic and conceptual problems that are not fully captured by classical models derived from the study of vascular and other acute focal brain lesions. This has led to a reformulation of our understanding of how language is organized in the brain. In this review we seek to provide the clinical neurologist with a practical and theoretical bridge between the patient presenting with word-finding difficulty in the clinic and the evidence of the brain sciences. We delineate key illustrative speech and language syndromes in the degenerative dementias, compare these syndromes with the syndromes of acute brain damage, and indicate how the clinical syndromes relate to emerging neurolinguistic, neuroanatomical and neurobiological insights. We propose a conceptual framework for the analysis of word-finding difficulty, in order both better to define the patient's complaint and its differential diagnosis for the clinician and to identify unresolved issues as a stimulus to future work.

Verb acquisition and representation in Alzheimer's disease

We examined the implicit acquisition and mental representation of a novel verb in patients with probable Alzheimer's disease (AD). Patients were exposed to the new verb in a naturalistic manner as part of a simple picture story. We probed grammatical, semantic and thematic matrix knowledge of the verb soon after presentation and again 1 week later. We found partial verb acquisition that was retained over 1 week. AD patients did not differ from controls in their acquisition and retention of a new verb's major grammatical subcategory, although they acquired little of its semantic properties and displayed minimal acquisition of the new word's thematic matrix. Moreover, AD patients appeared to maintain their acquired grammatical knowledge over 1 week. We discuss the implications of these findings from several perspectives, including the modularity of the language processing system, the relationship between episodic memory and semantic memory, and the role of the preserved implicit memory system in AD patients' partially successful lexical acquisition.

Effect of Antipsychotic Medication Use on Memory in Patients With Alzheimer’s Disease: Assessing the Potential Risk for Accelerated Recent Autobiographical Memory Loss

Autobiographical memory loss is a common and disturbing problem for individuals with Alzheimer's disease (AD). Patients with AD who are taking antipsychotic medications may be at further risk for loss of recent autobiographical memory because of the potential anticholinergic side effects of antipsychotics. The purpose of this post hoc, descriptive study was to compare the recent autobiographical memory scores of patients with AD taking antipsychotics to those who were not taking antipsychotics. The study population was composed of 35 patients with moderate-stage AD. Patients who were taking antipsychotics scored significantly worse on a recent autobiographical memory measure compared with patients who were not taking antipsychotics. This study provides further evidence for judicious use of antipsychotic medications with AD patients.

Relações entre controle executivo e memória episódica verbal no comprometimento cognitivo leve e na demência tipo Alzheimer

Este estudo comparou e relacionou o desempenho de idosos com Comprometimento Cognitivo Leve e Demência Tipo Alzheimer em testes de controle executivo e de memória episódica verbal. Para a avaliação da memória episódica verbal utilizamos a Tarefa de Recordação de Palavras Imediata e a Tarefa de Recordação de Palavras com Intervalo. Na avaliação do controle executivo foram utilizados, os seguintes testes: Random Number Generation, Trail Making Test, Fluência Verbal semântica e fonológica, Wisconsin Card Sorting Test, Reading Span Test e Brow-Peterson Test. Treze idosos do grupo controle foram equiparados quanto à idade e escolaridade com nove idosos com Comprometimento Cognitivo Leve e oito idosos com Demência Tipo Alzheimer. Foram encontradas diferenças e associações estatisticamente significantes em relação aos testes de controle executivo entre os grupos investigados. Apesar da presença de associações significativas entre a memória episódica verbal e o controle executivo, não foram evidenciados déficits do controle executivo nos idosos com Comprometimento Cognitivo Leve.

Categorization of object descriptions in Alzheimer's disease and frontotemporal dementia: limitation in rule-based processing

Studies of semantic memory in probable Alzheimer's disease (AD) have focused on the degradation of semantic knowledge, but other work in AD suggests an impairment in the semantic categorization processes that operate on this knowledge. We examined the categorization of object descriptions, where semantic category membership judgments were based on rule-based or similarity-based categorization processes. We found that AD patients were selectively limited in their semantic categorization under conditions requiring a rule-based approach. However, AD patients did not differ from healthy seniors under conditions based on judgments of overall similarity. We showed that this was not due to nonspecific or overall task-related difficulty associated with the rule condition by asking the subjects to use similarity-based judgments of perceptually degraded versions of the stimuli. The results of this condition did not differ from other similarity-based judgments but did differ from the rule-based condition in AD. Rule-based judgments of semantic category membership correlated with executive measures of inhibitory control and mental search, but not with measures of episodic memory or overall dementia severity, suggesting a contribution of executive resources to rule-based semantic categorization. Moreover, the pattern of limited rule-based categorization in AD closely resembled the performance profile of patients with frontotemporal dementia, further implying that executive resource limitations underlie AD patients' limited rule-based semantic categorization. These findings suggest that semantic memory difficulty in AD is due in part to a deficit in executive processes that are central to rule-based categorization in semantic memory.

Neural Basis for Verb Processing in Alzheimer's Disease: An fMRI Study

Patients with probable Alzheimer's disease (AD) have difficulty understanding verbs. To investigate the neural basis for this deficit, the authors used functional magnetic resonance imaging to examine patterns of neural activation during verb processing in 11 AD patients compared with 16 healthy seniors. Subjects judged the pleasantness of verbs, including MOTION verbs and COGNITION verbs. Healthy seniors and AD patients both activated posterolateral temporal and inferior frontal regions during judgments of verbs. These activations were relatively reduced and somewhat changed in their anatomic distribution in AD patients compared with healthy seniors, particularly for the subcategory of MOTION verbs, but AD patients showed minimal activation in association with COGNITION verbs. These findings imply that poor performance with verbs in AD is due in part to altered activation of the large-scale neural network that supports verb processing.