A common mechanism in verb and noun naming deficits in Alzheimer's patients

Impaired language in Alzheimer's disease: A comparison between English and Persian implicates content-word frequency rather than the noun-verb distinction

This study challenges the conventional psycholinguistic view that the distinction between nouns and verbs is pivotal in understanding language impairments in neurological disorders. Traditional views link frontal brain region damage with verb processing deficits and posterior temporoparietal damage with noun difficulties. However, this perspective is contested by findings from patients with Alzheimer's disease (pwAD), who show impairments in both word classes despite their typical temporoparietal atrophy. Notably, pwAD tend to use semantically lighter verbs in their speech than healthy individuals. By examining English-speaking pwAD and comparing them with Persian-speaking pwAD, this research aims to demonstrate that language impairments in Alzheimer's disease (AD) stem from the distributional properties of words within a language rather than distinct neural processing networks for nouns and verbs. We propose that the primary deficit in AD language production is an overreliance on high-frequency words. English has a set of particularly high-frequency verbs that surpass most nouns in usage frequency. Since pwAD tend to use high-frequency words, the byproduct of this word distribution in the English language would be an over-usage of high-frequency verbs. In contrast, Persian features complex verbs with an overall distribution lacking extremely high-frequency verbs like those found in English. As a result, we hypothesize that Persian-speaking pwAD would not have a bias toward the overuse of high-frequency verbs. We analyzed language samples from 95 English-speaking pwAD and 91 healthy controls, along with 27 Persian-speaking pwAD and 27 healthy controls. Employing uniform automated natural language processing methods, we measured the usage rates of nouns, verbs, and word frequencies across both cohorts. Our findings showed that English-speaking pwAD use higher-frequency verbs than healthy individuals, a pattern not mirrored by Persian-speaking pwAD. Crucially, we found a significant interaction between the frequencies of verbs used by English and Persian speakers with and without AD. Moreover, regression models that treated noun and verb frequencies as separate predictors did not outperform models that considered overall word frequency alone in classifying AD. In conclusion, this study suggests that language abnormalities among English-speaking pwAD reflect the unique distributional properties of words in English rather than a universal noun-verb class distinction. Beyond offering a new understanding of language abnormalities in AD, the study highlights the critical need for further investigation across diverse languages to deepen our insight into the mechanisms of language impairments in neurological disorders.

Assessment of Language Function in Older Mandarin-Speaking Adults with Mild Cognitive Impairment using Multifaceted Language Tests

BACKGROUND

Individuals with amnestic mild cognitive impairment (aMCI), especially for those with multidomain cognitive deficits, should be clinically examined for determining risk of developing Alzheimer's disease. English-speakers with aMCI exhibit language impairments mostly at the lexical-semantic level. Given that the language processing of Mandarin Chinese is different from that of alphabetic languages, whether previous findings for English-speakers with aMCI can be generalized to Mandarin Chinese speakers with aMCI remains unclear.

OBJECTIVE

This study examined the multifaceted language functions of Mandarin Chinese speakers with aMCI and compared them with those without cognitive impairment by using a newly developed language test battery.

METHODS

Twenty-three individuals with aMCI and 29 individuals without cognitive impairment were recruited. The new language test battery comprises five language domains (oral production, auditory and reading comprehension, reading aloud, repetition, and writing).

RESULTS

Compared with the controls, the individuals with aMCI exhibited poorer performance in the oral production and auditory and reading comprehension domains, especially on tests involving effortful lexical and semantic processing. Moreover, the aMCI group made more semantic naming errors compared with their counterparts and tended to experience difficulty in processing items belonging to the categories of living objects.

CONCLUSIONS

The pattern identified in the present study is similar to that of English-speaking individuals with aMCI across multiple language domains. Incorporating language tests involving lexical and semantic processing into clinical practice is essential and can help identify early language dysfunction in Mandarin Chinese speakers with aMCI.

Effects of transcranial magnetic stimulation on neurobiological changes in Alzheimer's disease (Review)

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by cognitive decline and brain neuronal loss. A pioneering field of research in AD is brain stimulation via electromagnetic fields (EMFs), which may produce clinical benefits. Noninvasive brain stimulation techniques, such as transcranial magnetic stimulation (TMS), have been developed to treat neurological and psychiatric disorders. The purpose of the present review is to identify neurobiological changes, including inflammatory, neurodegenerative, apoptotic, neuroprotective and genetic changes, which are associated with repetitive TMS (rTMS) treatment in patients with AD. Furthermore, it aims to evaluate the effect of TMS treatment in patients with AD and to identify the associated mechanisms. The present review highlights the changes in inflammatory and apoptotic mechanisms, mitochondrial enzymatic activities, and modulation of gene expression (microRNA expression profiles) associated with rTMS or sham procedures. At the molecular level, it has been suggested that EMFs generated by TMS may affect the cell redox status and amyloidogenic processes. TMS may also modulate gene expression by acting on both transcriptional and post‑transcriptional regulatory mechanisms. TMS may increase brain cortical excitability, induce specific potentiation phenomena, and promote synaptic plasticity and recovery of impaired functions; thus, it may re‑establish cognitive performance in patients with AD.

Revealing the Roles of Part-of-Speech Taggers in Alzheimer’s Disease Detection: A Scientific Discovery Using One-intervention Causal Explanation (Preprint)

BACKGROUND

Recently, rich computational methods that use deep learning or machine learning have been developed using linguistic biomarkers for the diagnosis of early-stage Alzheimer disease (AD). Moreover, some qualitative and quantitative studies have indicated that certain part-of-speech (PoS) features or tags could be good indicators of AD. However, there has not been a systematic attempt to discover the underlying relationships between PoS features and AD. Moreover, there has not been any attempt to quantify the relative importance of PoS features in detecting AD.

OBJECTIVE

Our goal was to disclose the underlying relationship between PoS features and AD, understand whether PoS features are useful in AD diagnosis, and explore which PoS features play a vital role in the diagnosis.

METHODS

The DementiaBank, containing 1049 transcripts from 208 patients with AD and 243 transcripts from 104 older control individuals, was used. A total of 27 PoS features were extracted from each record. Then, the relationship between AD and each of the PoS features was explored. A transformer-based deep learning model for AD prediction using PoS features was trained. Then, a global explainable artificial intelligence method was proposed and used to discover which PoS features were the most important in AD diagnosis using the transformer-based predictor. A global (model-level) feature importance measure was derived as a summary from the local (example-level) feature importance metric, which was obtained using the proposed causally aware counterfactual explanation method. The unique feature of this method is that it considers causal relations among PoS features and can, hence, preclude counterfactuals that are improbable and result in more reliable explanations.

RESULTS

The deep learning-based AD predictor achieved an accuracy of 92.2% and an F₁-score of 0.955 when distinguishing patients with AD from healthy controls. The proposed explanation method identified 12 PoS features as being important for distinguishing patients with AD from healthy controls. Of these 12 features, 3 (25%) have been identified by other researchers in previous works in psychology and natural language processing. The remaining 75% (9/12) of PoS features have not been previously identified. We believe that this is an interesting finding that can be used in creating tests that might aid in the diagnosis of AD. Note that although our method is focused on PoS features, it should be possible to extend it to more types of features, perhaps even those derived from other biomarkers, such as syntactic features.

CONCLUSIONS

The high classification accuracy of the proposed deep learner indicates that PoS features are strong clues in AD diagnosis. There are 12 PoS features that are strongly tied to AD, and because language is a noninvasive and potentially cheap method for detecting AD, this work shows some promising directions in this field.

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.

Dissociating nouns and verbs in temporal and perisylvian networks: Evidence from neurodegenerative diseases

Naming of nouns and verbs can be selectively impaired in neurological disorders, but the specificity of the neural and cognitive correlates of such dissociation remains unclear. Functional imaging and stroke research sought to identify cortical regions selectively recruited for nouns versus verbs, yet findings are inconsistent. The present study investigated this issue in neurodegenerative diseases known to selectively affect different brain networks, thus providing new critical evidence of network specificity. We examined naming performances on nouns and verbs in 146 patients with different neurodegenerative syndromes (Primary Progressive Aphasia - PPA, Alzheimer's disease - AD, and behavioral variant Frontotemporal Dementia - FTD) and 30 healthy adults. We then correlated naming scores with MRI-derived cortical thickness values as well as with performances in semantic and syntactic tasks, across all subjects. Results indicated that patients with the semantic variant PPA named significantly fewer nouns than verbs. Instead, nonfluent/agrammatic PPA patients named fewer verbs than nouns. Across all subjects, performance on nouns (adjusted for verbs) specifically correlated with cortical atrophy in left anterior temporal regions, and performance on verbs (adjusted for nouns) with atrophy in left inferior and middle frontal, inferior parietal and posterior temporal regions. Furthermore, lower lexical-semantic abilities correlated with deficits in naming both nouns and verbs, while lower syntactic abilities only correlated with naming verbs. Our results show that different neural and cognitive mechanisms underlie naming of specific grammatical categories in neurodegenerative diseases. Importantly, our findings showed that verb processing depends on a widespread perisylvian networks, suggesting that some regions might be involved in processing different types of action knowledge. These findings have important implications for early differential diagnosis of neurodegenerative disorders.

Quantitative and Qualitative Analysis of Verb Fluency Performance in Individuals With Probable Alzheimer's Disease and Healthy Older Adults

Purpose To date, verb fluency tasks have been mainly analyzed quantitatively for individuals with dementia. Qualitative analysis, however, such as examining the semantic and psycholinguistic content of the responses might further inform researchers and clinicians about patients' cognitive and linguistic status. Therefore, the current study examined psycholinguistic and lexical characteristics of verb fluency responses in individuals with probable Alzheimer's disease (pAD) and healthy older adults to delineate qualitative and quantitative differences between the two groups. Method The verb fluency responses from participants with pAD (amnestic type) were compared to those from age- and education-matched healthy older adults. The responses were analyzed with respect to the number and proportion of correct responses, word frequency, age of acquisition, phoneme and syllable length, and neighborhood density. The verb responses were also categorized into mental state verbs and action verbs. Additionally, a battery of cognitive-linguistic tests was administered, and for each group, relationships between correct verb fluency responses and other cognitive-linguistic skills were investigated using correlation and regression analyses. Results Similar to previous findings regarding noun retrieval in dementia, the results revealed that individuals with pAD not only produced fewer correct verb fluency responses but also generated little to no mental state verbs compared to the control group. The group with pAD also produced verbs with shorter phoneme and syllable lengths, higher word frequency, and earlier age of acquisition ratings relative to the healthy older adults. The number of correct verb fluency responses was mainly predicted by a reading comprehension score in the pAD group and a nonverbal fluency test score in the healthy group. Conclusion The current quantitative and qualitative findings add support to the contention that lexical-semantic impairments underlie word retrieval problems in pAD and such difficulties present in generative naming paradigms and also across grammatical categories.

Category-specific verb-semantic deficits in Alzheimer's disease: Evidence from static and dynamic action naming

We investigated the representation and breakdown of verb knowledge employing different syntactic and semantic classes of verbs in a group of individuals with probable Alzheimer's Disease (pAD). In an action naming task with coloured photographs (Fiez & Tranel, 1997. Standardized stimuli and procedures for investigating the retrieval of lexical and conceptual knowledge for action. Memory and Cognition, 25(4), 543-569. https://doi.org/10.3758/BF03201129), pAD individuals were impaired for naming actions compared to objects. Verb tense was also affected, with simple-past (e.g., chopped) being more difficult to name than the gerundial form (e.g., chopping). Employing action-naming with short movies depicting events and states, we contrasted three verb classes based on their hypothetical structural and semantic/conceptual properties: argument structure, thematic structure, and conceptual templates. The three classes were: causatives (peel), verbs of perception (hear), and verbs of motion (run) Overall, results suggest that individuals with pAD are selectively impaired for verb tense and thematic assignment, but not conceptual-template complexity. Methodologically, we also show that dynamic scenes are more ecologically valid than static scenes to probe verb knowledge in AD.

Distinct neural mechanisms underlying conceptual knowledge of manner and instrument verbs

Studies on the organization of conceptual knowledge have examined categories of concrete nouns extensively. Less is known about the neural basis of verb categories suggested by linguistic theories. We used functional MRI to examine the differences between manner verbs, which encode information about the manner of an action, versus instrument verbs, which encode information about an object as part of their meaning. Using both visual and verbal stimuli and a combination of univariate and multivariate pattern analyses, our results show that accessing conceptual representations of instrument class involves brain regions typically associated with complex action and object perception, including the anterior inferior parietal cortex and occipito-temporal cortex. On the other hand, accessing conceptual representations of the manner class involves regions that are commonly associated with the processing of visual and biological motion, in the posterior superior temporal sulcus. These findings support the idea that the semantics of manner and instrument verbs are supported by distinct neural mechanisms.

Test-retest reliability in an fMRI study of naming in dementia

fMRI has been used as an outcome measure in dementia treatment studies, with many previous studies comparing only single pre- and post-treatment fMRI scans to determine treatment-induced neural changes, while utilizing single subject experimental designs. The purpose of the current study was to evaluate fMRI test-retest reliability in dementia patients and typical older adults using noun and verb confrontation naming to evaluate the validity of using a single pre/post-treatment scan comparison. Seven individuals with dementia and 9 control participants were tested three times over two months using the same fMRI procedures. Differences in individual and group level activation patterns were observed that varied across time. Additionally, the extent of variability fluctuated across individuals, groups, and the grammatical category of target words. Our findings suggested that one time fMRI scanning may inadequately represent an individual's typical brain activation pattern, particularly an individual with dementia. Thus, multiple imaging baselines are recommended.

Neural representation of word categories is distinct in the temporal lobe: An activation likelihood analysis

The distinction between nouns and verbs is a language universal. Yet, functional neuroimaging studies comparing noun and verb processing have yielded inconsistent findings, ranging from a complete frontal(verb)-temporal(noun) dichotomy to a complete overlap in activation patterns. The current study addressed the debate about neural distinctions between nouns and verbs by conducting an activation likelihood estimation (ALE) meta-analysis of probabilistic cytoarchitectonic maps. Two levels of analysis were conducted: simple effects (Verbs vs. Baseline, Nouns vs. Baseline), and direct comparisons (Verbs vs. Nouns, Nouns vs. Verbs). Nouns were uniquely associated with a left medial temporal cluster (BA37). Activation foci for verbs included extensive inferior frontal (BA44-47) and mid-temporal (BA22, 21) regions in the left hemisphere. These findings confirm that the two grammatical classes have distinct neural architecture in supra-modal brain regions. Further, nouns and verbs overlapped in a small left lateral inferior temporal activation cluster (BA37), which is a region for modality-independent, grammatical class-independent lexical representations. These findings are most consistent with the view that as one acquires language, linguistic representations for a lexical category shift from the modality specific cortices which represent prototypical members of that category (e.g., motion for verbs) to abstract amodal representations in close proximity to modality specific cortices.

Semantic Feature Disturbance in Alzheimer Disease: Evidence from an Object Decision Task

BACKGROUND AND OBJECTIVE

It is widely held that semantic disturbance in Alzheimer disease (AD) involves the loss of distinctive features but the relative sparing of nondistinctive features. Many previous studies of semantic feature disturbance have used cognitively challenging tasks with verbal stimuli that allow for potential cognitive confounds. Our objective was to use a task with lower memory demands to investigate distinctive feature disturbance in AD.

METHODS

We used an object decision task to compare the processing of distinctive and nondistinctive semantic features in people with AD and age-matched controls. The task included six conditions based on the relationship between each prime and target object. We tested the processing of distinctive and nondistinctive features by selectively altering distinctive and nondistinctive semantic features between prime and target pairs.

RESULTS

Performance accuracy was significantly lower for participants with AD than for age-matched controls when distinctive features were manipulated, but no difference was found when nondistinctive features were manipulated.

CONCLUSIONS

Our results provide evidence of semantic content disturbance in AD in the context of a task with low cognitive demands.

Comprehension and production of nouns and verbs in temporal lobe epilepsy

Previous research on linguistic performance at the single-word level in patients with temporal lobe epilepsy (TLE) has mostly been limited to the comprehension and production of nouns, and findings have been inconsistent. Results are likewise limited and controversial regarding the lateralization of the epileptogenic focus. The present study investigates comprehension and production of nouns and verbs in patients with left and right TLE (12 in each group). We designed a comprehension (word-picture matching) test and a production (naming) test, matched on a range of psycholinguistic parameters for the two word classes. The results showed impaired verb comprehension in patients with left TLE and impaired noun and verb production in both groups of patients compared to the control group. Patients with left and right TLE differed significantly on verb comprehension and noun production, whereas verb production was equally impaired in the two groups of patients. These findings suggest difficulties with single-word processing in patients with both left and right TLE, which are more prominent for verbs than for nouns in patients with left TLE. The verb production (action naming) test turned out to be the most effective tool for assessing linguistic difficulties at the single-word level in patients with TLE.

Cognitive Correlates of Perseverations in Individuals with Memory Impairment

OBJECTIVE

This study examines which cognitive measure best accounts for perseverations in individuals with memory impairment.

METHOD

The sample included 85 individuals, of whom 21 had subjective memory concerns, 27 had mild cognitive impairment, and 37 had Alzheimer's disease. Participants produced responses on a semantic category fluency task and on the ideational fluency (IF) task from the Cambridge Cognitive Examination-Revised. Measures of word finding, working memory, and abstract thinking were also assessed.

RESULTS

Significant group differences in percentage of perseverations emerged on both tasks. No cognitive measure accounted for the percentage of perseverations on the semantic fluency task. A measure of abstract thinking was the best predictor of the percentage of perseverations on the IF task, followed by a measure of working memory.

CONCLUSIONS

The underlying cognitive mechanisms that lead to perseverations differ across tasks, with perseverations on the IF task reflecting both conceptual deficits and working memory limitations.

Language Specific and Language General Motivations of Production Choices: A Multi-Clause and Multi-Language Investigation

Cross-linguistic studies allow for analyses that would be impossible in a single language. To better understand the factors that underlie sentence production, we investigated production choices in main and relative clause production tasks in three languages: English, Japanese and Korean. The effects of both non-linguistic attributes (such as conceptual animacy) and language specific properties (such as word order) were investigated. Japanese and Korean are structurally similar to each other but different from English, which allowed for an investigation of the production consequences of non-linguistic attributes in different typological or word order contexts (when Japanese and Korean speakers make similar production choices that are unlike those of English speakers), as well as production choices that differ despite typological similarity (when Japanese and Korean speakers make different choices). Speakers of all three languages produced more passive utterances when describing animate entities, but the overall rate of passives varied by task and language. Further, the sets of items that were most likely to elicit passives varied by language, with Japanese and Korean speakers more likely to produce passives when patients were adversely affected by the depicted event. These results suggest a number of factors that contribute to language production choices across three languages, and how general cognitive constraints on sentence production may interact with the structure of a specific language.

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.

Word retrieval in picture descriptions produced by individuals with Alzheimer's disease

What can tests of single-word production tell us about word retrieval in connected speech? We examined this question in 20 people with Alzheimer's disease (AD) and in 20 cognitively intact individuals. All participants completed tasks of picture naming and semantic fluency and provided connected speech through picture descriptions. Picture descriptions were analyzed for total word output, percentages of content words, percentages of nouns, and percentages of pronouns out of all words, type-token ratio of all words and type-token ratio of nouns alone, mean frequency of all words and mean frequency of nouns alone, and mean word length. Individuals with AD performed worse than did cognitively intact individuals on the picture naming and semantic fluency tasks. They also produced a lower proportion of content words overall, a lower proportion of nouns, and a higher proportion of pronouns, as well as more frequent and shorter words on picture descriptions. Group differences in total word output and type-token ratios did not reach significance. Correlations between scores on tasks of single-word retrieval and measures of retrieval in picture descriptions emerged in the AD group but not in the control group. Scores on a picture naming task were associated with difficulties in word retrieval in connected speech in AD, while scores on a task of semantic verbal fluency were less useful in predicting measures of retrieval in context in this population.

Using informative verbal exchanges to promote verb retrieval in nonfluent aphasia

PURPOSE

The goal of this study was to determine whether positive treatment effects of a modified constraint-induced language therapy focused on verb production would generalize to unpracticed items and tasks.

METHOD

Four individuals participated in a single-subject treatment design protocol. The treatment involved intensive practice producing verbs in sentences in an informative communicative exchange. Direct treatment outcome was examined by measuring the accuracy of producing practiced verbs in an action description task, a task similar to those used in treatment. Generalization was assessed by measuring production of unpracticed verbs and sentence grammaticality in the action description task and by measuring verb production and sentence grammaticality in 2 relatively unstructured (unpracticed) language tasks.

RESULTS

Two of the 4 participants showed a direct treatment effect, producing a greater number of practiced verbs in the action description task following treatment compared with before treatment. All participants improved sentence grammaticality following treatment, although grammaticality was not explicitly targeted in therapy. Generalization to unpracticed, less-structured tasks was variable across the participants.

CONCLUSION

Patterns of generalization may depend on participants' specific language deficits and production characteristics, on the language tasks used, and on the measures used to detect change and assess generalization.

Lexical retrieval in discourse: an early indicator of Alzheimer's dementia

We examined the progression of lexical-retrieval deficits in individuals with neuropathologically determined Alzheimer's disease (AD; n = 23) and a comparison group without criteria for AD (n = 24) to determine whether linguistic changes were a significant marker of the disease. Our participants underwent multiple administrations of a neuropsychological battery, with initial administration occurring on average 16 years prior to death. The battery included the Boston Naming Test (BNT), a letter fluency task (FAS) and written description of the Cookie Theft Picture (CTP). Repeated measures analysis revealed that the AD-group showed progressively greater decline in FAS and CTP lexical performance than the comparison group. Cross-sectional time-specific group comparisons indicated that the CTP differentiated performance between the two groups at 7-9 years prior to death and FAS and BNT only at 2-4 years. These results suggest that lexical-retrieval deficits in written discourse serve as an early indicator of AD.

Effects of Noun-Verb Conceptual/ Phonological Relatedness on Verb Production Changes in Broca's Aphasia

BACKGROUND

Individuals with Broca's aphasia show better performance on nouns than on verbs, but distinction between nouns and verbs is not always clear; some verbs are conceptually and/ or phonologically related to nouns, while others are not. Inconsistent results on effects of noun-verb relatedness on verb production have been reported in the literature.

AIMS

We investigated (1) whether verb instrumentality (a conceptual relationship to nouns) or homonymy (a phonological relationship to nouns) would affect verb production in individuals with Broca's aphasia and (2) whether conceptual/ phonological noun-verb relationship would affect responsiveness to aphasia therapy that focused on verb production.

METHODS & PROCEDURES

Three English speaking individuals with Broca's aphasia produced 96 verbs in sentences in response to picture stimuli. The target verbs included those that use an instrument and those that do not (e.g., to hammer vs. to yawn) and verbs that are phonologically identical to a related noun (e.g., to comb - a comb), morpho-phonologically-related to a noun (e.g., to grind - a grinder), and verbs for which there is no phonologically similar noun (e.g., to lean). The participants' verb retrieval ability was assessed before and after a 4-week period of aphasia therapy.

OUTCOMES & RESULTS

The participants produced more accurate instrumental than non-instrumental verbs both pre- and post-treatment. They also produced more verbs correctly that are homonyms of nouns than verbs that are phonologically related or unrelated to nouns before treatment. However, the effect of homonymy was not observed following treatment.

CONCLUSION

Individuals with Broca's aphasia were more accurate in their production of verbs that were conceptually and phonologically related to nouns than on verb that were not. The performance on verb production improved significantly after therapy. We interpret the results to indicate that whereas prior to treatment the participants relied on phonologically related nouns to retrieve the target verbs, this reliance on knowledge of nouns decreased following therapy that was designed to improve verb production.

Validation of the Literacy Independent Cognitive Assessment

BACKGROUND

Low education and illiteracy are associated with an increased risk of dementia. This study aimed to develop a neuropsychological test battery applicable to both illiterate and literate elderly and to assess its reliability and validity for a diagnosis of dementia.

METHODS

We developed the Literacy Independent Cognitive Assessment (LICA), which consists of 13 subtests assessing memory, language, visuoconstruction, executive function, attention and calculation. We investigated its reliability and validity on 152 patients with dementia, 66 with mild cognitive impairment and 639 normal controls.

RESULTS

The subtests were found to be applicable to most of the illiterate normal controls (97.3%) and were found to have high inter-rater reliabilities (r = 0.85-1.00, p < 0.001) and moderate to high test-retest reliabilities (r = 0.50-0.86, p < 0.001). The LICA performed well in discriminating participants across Clinical Dementia Rating stages and showed excellent internal consistency and good concurrent validity with the Korean Mini-mental State Examination in both literate and illiterate participants. The area under the curve of the receiver operating characteristic was 0.985 in each of the two literacy groups. Sensitivity and specificity of the LICA to make a diagnosis of dementia was 91.9% and 91.8% at the cutoff point of 186.0 in the literate subjects and 96.2% and 91.1% at the cutoff point of 154.5 in the illiterate subjects. The battery was factored into two separate factors consisting of verbal memory tests and tests for other cognitive domains.

CONCLUSION

The LICA is a valid and reliable instrument for a diagnosis of dementia in both illiterate and literate elderly.

The common objects memory test (COMT): a simple test with cross-cultural applicability

The Common Objects Memory Test (COMT) was developed to assess age-related memory impairments in individuals with a range of educational, language and cultural backgrounds. The COMT is a list-learning protocol that uses photographs of common objects to bypass difficulties posed by written words for individuals who are illiterate or have limited education. Preliminary data are presented for 336 healthy adults and 90 patients with dementia. Their age ranged from 54 to 99 years, education ranged from 0 to 22 years, and they were from five culturally and linguistically distinct populations: Caucasian and African-American English speakers, and native Chinese, Spanish, and Vietnamese speakers. Performance on the COMT was influenced by age, but little influenced by education, and un-influenced by gender or ethnic background. Among 11 neuropsychological tests, the recall scores from the COMT best distinguished healthy individuals from patients with dementia, underscoring its clinical utility for ethnically diverse populations.