Language performance in Alzheimer's disease and mild cognitive impairment: a comparative review

Deficits in narrative discourse elicited by visual stimuli are already present in patients with mild cognitive impairment

Language batteries used to assess the skills of elderly individuals, such as naming and semantic verbal fluency, present some limitations in differentiating healthy controls from patients with amnestic mild cognitive impairment (a-MCI). Deficits in narrative discourse occur early in dementia caused by Alzheimer's disease (AD), and the narrative discourse abilities of a-MCI patients are poorly documented. The present study sought to propose and evaluate parameters for investigating narrative discourse in these populations. After a pilot study of 30 healthy subjects who served as a preliminary investigation of macro- and micro-linguistic aspects, 77 individuals (patients with AD and a-MCI and a control group) were evaluated. The experimental task required the participants to narrate a story based on a sequence of actions visually presented. The Control and AD groups differed in all parameters except narrative time and the total number of words recalled. The a-MCI group displayed mild discursive difficulties that were characterized as an intermediate stage between the Control and AD groups' performances. The a-MCI and Control groups differed from the AD group with respect to global coherence, discourse type and referential cohesion. The a-MCI and AD groups were similar to one another but differed from the Control group with respect to the type of words recalled, the repetition of words in the same sentence, the narrative structure and the inclusion of irrelevant propositions in the narrative. The narrative parameter that best distinguished the three groups was the speech effectiveness index. The proposed task was able to reveal differences between healthy controls and groups with cognitive decline. According to our findings, patients with a-MCI already present narrative deficits that are characterized by mild discursive difficulties that are less severe than those found in patients with AD.

Review of information and communication technology devices for monitoring functional and cognitive decline in Alzheimer's disease clinical trials

Detecting and monitoring early cognitive impairment in Alzheimer's disease (AD) is a significant need in the field of AD therapeutics. Successful AD clinical trial designs have to overcome challenges related to the subtle nature of early cognitive changes. Continuous unobtrusive assessments using Information and Communication Technology (ICT) devices to capture markers of intra-individual change over time to assess cognitive and functional disability therefore offers significant benefits. We review the literature and provide an overview on randomized clinical trials in AD that use intelligent systems to monitor functional decline, as well as strengths, weaknesses, and future directions for the use of ICTs in a new generation of AD clinical trials.

Semantic profiles in mild cognitive impairment associated with Alzheimer's and Parkinson's diseases

The temporal and the prefrontal cortices have different roles in semantic information processing: the temporal lobe is where knowledge is stored (Graham and Hodges, 1997), whereas the prefrontal cortex is more specifically involved in executive aspects of semantic processing. Relatively little is known about the semantic profiles of mild cognitive impairment (MCI) in Alzheimer's disease (AD) and Parkinson's disease (PD). This observational study investigated naming and semantic questionnaire performances in three groups of subjects: 10 patients with the amnestic-type MCI prodrome of AD (aMCI), 10 patients with early-stage executive-type MCI in PD (MCI-PD), and 10 normal subjects. The MCI-PD subjects demonstrated inferior performances on a semantic questionnaire, whereas the aMCI group displayed modest difficulties in a naming task. These differences may be explained by topographical differences in pathological involvement. Since the frontal areas are more functionally impaired in PD, we hypothesize that the semantic deficit may be a consequence of a deficiency in control of semantic processing. On the other hand, the semantic deficit in aMCI may be related to a lexical-semantic storage dysfunction resulting from pathological involvement of the temporal lobe.

Automatic speech analysis for the assessment of patients with predementia and Alzheimer's disease

Background

To evaluate the interest of using automatic speech analyses for the assessment of mild cognitive impairment (MCI) and early-stage Alzheimer's disease (AD).

Methods

Healthy elderly control (HC) subjects and patients with MCI or AD were recorded while performing several short cognitive vocal tasks. The voice recordings were processed, and the first vocal markers were extracted using speech signal processing techniques. Second, the vocal markers were tested to assess their “power” to distinguish among HC, MCI, and AD. The second step included training automatic classifiers for detecting MCI and AD, using machine learning methods and testing the detection accuracy.

Results

The classification accuracy of automatic audio analyses were as follows: between HCs and those with MCI, 79% ± 5%; between HCs and those with AD, 87% ± 3%; and between those with MCI and those with AD, 80% ± 5%, demonstrating its assessment utility.

Conclusion

Automatic speech analyses could be an additional objective assessment tool for elderly with cognitive decline.

Impairment of homonymous processing in Alzheimer's disease

An important issue in research on language is how concepts are represented and associated with each other in the brain. Many investigations have focused on language ambiguity and the phenomenon of homonymy in which a single lexical item, presenting the same form, is related to different meanings. Our study aims to test the hypothesis that weak association of meaning characterizing homonyms may be especially prone to brain damage. To verify this hypothesis a test of attribution of the meaning of homonymous words, the Humpty Dumpty (HD) test, was applied to 50 patients with Alzheimer's disease (AD) and 50 healthy subjects. Results show that AD patients are impaired in the HD test in an early phase of disease and that performance correlates with naming ability and phonological fluency. The data are in keeping with a growing body of literature that supports dual impairment to the semantic system in AD, i.e., to semantic knowledge and active processing and access to the semantic field. The evaluation of the ability to resolve homonymous ambiguity, using the HD test, may provide a useful and quick clinical tool to detect the anomalies of the semantic network linked to either a loss of the core system where meaning of words is stored or an impairment of the access to an intact semantic representation.

Preparing a persian version of kimberley indigenous cognitive assessment for assessing the cognitive problems of illiterate geriatric patients

BACKGROUND

The rate of dementia is increasing rapidly. With the recognized high rate of illiteracy among geriatric patients, preparing an appropriate device for special screening among the low-educated elderly seems to be necessary. The aim of this study is to prepare and assess the psychometric properties of the Persian version of the Kimberley Indigenous Cognitive Assessment (KICA) in Iranian adults, in 2012.

MATERIALS AND METHODS

One hundred and eighty elders participated in this psychometric study. Ninety patients with dementia according to the Diagnostic and Statistical Manual of Mental Disorders, fourth Edition, Text Revision (DSM-IV-TR) criteria, who had been admitted to Geriatrics and Neurology in some of the private clinics in Esfahan, Iran, in 2012, were selected. The rest of the participants were normal persons with the same demographic characteristics as the dementia group, who were selected from the patients' acquaintances and from the Retired Personnel Organization. The statistical tools were the KICA scale, Mini-Mental State Examination (MMSE), and Modified Mini-Mental State Examination (3MSE).

RESULTS

The best clinical cutoff point of the test was 31, with a sensitivity of 92% and specificity of 88%. The Cronbach's alpha coefficient of KICA was 0.93. Among the KICA's subscales, the maximum Cronbach's alpha coefficient belonged to Praxis (α = 0.933) and the minimum one belonged to Delayed Recall (α = 0.927). The correlation coefficients of the KICA score with MMSE and 3MSE were 0.58 and 0.57, respectively.

CONCLUSION

The KICA test has been seen to be a reliable and valid tool to assess cognitive impairment in the aged people of Iran. The KICA test can be used as a cognitive assessment test for distinguishing patients with dementia, especially illiterate ones from other healthy people in Iran.

Non-literal language deficits in mild cognitive impairment

BACKGROUND

Verbal language deteriorates in Alzheimer's disease, contributing to dramatic disturbances in the ability to communicate. The presence of language disturbances may be detected at earlier phases of the neurodegenerative process, like mild cognitive impairment (MCI). In daily verbal interactions, people mostly use literal language, but sometimes they employ non-literal language, which requires listeners to interpret messages beyond the plain meaning of the words and can be quite demanding. In the present study, we tested the hypotheses that patients with MCI may have deficits in non-literal language, and these deficits are more pronounced than deficits in literal language.

METHODS

Participants were recruited in a private memory clinic and senior universities. General cognitive evaluation included a comprehensive neuropsychological battery, the Mini-Mental State Examination, and the instrumental activities of daily living scale. Literal language was assessed with the semantic decision test, Token Test, and literal text comprehension test, and non-literal language with the proverbs comprehension, idiomatic expressions and non-literal text comprehension tests.

RESULTS

Fifty-two participants with MCI and 31 controls were recruited. Patients with MCI had lower scores in all complex language tests, both literal (Token Test, semantic decision and literal text) and non-literal (proverbs, idiomatic expressions, and non-literal text), than the controls; the difference in literal text score was marginally significant. As much as 69% of MCI participants had deficits (performance below 1.5 SD of the mean) on at least one of the complex language tasks. Deficits were more frequent on the proverbs comprehension and semantic decision tests, and the deficits on these tests did not significantly differ from that on the Token Test.

CONCLUSION

Patients with MCI are hindered in understanding complex language, both literal and non-literal. In daily living, these complex language deficits could compromise effective verbal interactions with the others. Amelioration of these deficits should be an important intervention target as part of a comprehensive rehabilitation strategy for patients with cognitive decline.

Graph analysis of verbal fluency test discriminate between patients with Alzheimer's disease, mild cognitive impairment and normal elderly controls

Verbal fluency is the ability to produce a satisfying sequence of spoken words during a given time interval. The core of verbal fluency lies in the capacity to manage the executive aspects of language. The standard scores of the semantic verbal fluency test are broadly used in the neuropsychological assessment of the elderly, and different analytical methods are likely to extract even more information from the data generated in this test. Graph theory, a mathematical approach to analyze relations between items, represents a promising tool to understand a variety of neuropsychological states. This study reports a graph analysis of data generated by the semantic verbal fluency test by cognitively healthy elderly (NC), patients with Mild Cognitive Impairment-subtypes amnestic (aMCI) and amnestic multiple domain (a+mdMCI)-and patients with Alzheimer's disease (AD). Sequences of words were represented as a speech graph in which every word corresponded to a node and temporal links between words were represented by directed edges. To characterize the structure of the data we calculated 13 speech graph attributes (SGA). The individuals were compared when divided in three (NC-MCI-AD) and four (NC-aMCI-a+mdMCI-AD) groups. When the three groups were compared, significant differences were found in the standard measure of correct words produced, and three SGA: diameter, average shortest path, and network density. SGA sorted the elderly groups with good specificity and sensitivity. When the four groups were compared, the groups differed significantly in network density, except between the two MCI subtypes and NC and aMCI. The diameter of the network and the average shortest path were significantly different between the NC and AD, and between aMCI and AD. SGA sorted the elderly in their groups with good specificity and sensitivity, performing better than the standard score of the task. These findings provide support for a new methodological frame to assess the strength of semantic memory through the verbal fluency task, with potential to amplify the predictive power of this test. Graph analysis is likely to become clinically relevant in neurology and psychiatry, and may be particularly useful for the differential diagnosis of the elderly.

Potential benefits of mindfulness-based interventions in mild cognitive impairment and Alzheimer's disease: an interdisciplinary perspective

The present article is based on the premise that the risk of developing Alzheimer's disease (AD) from its prodromal phase (mild cognitive impairment; MCI) is higher when adverse factors (e.g., stress, depression, and metabolic syndrome) are present and accumulate. Such factors augment the likelihood of hippocampal damage central in MCI/AD aetiology, as well as compensatory mechanisms failure triggering a switch toward neurodegeneration. Because of the devastating consequences of AD, there is a need for early interventions that can delay, perhaps prevent, the transition from MCI to AD. We hypothesize that mindfulness-based interventions (MBI) show promise with regard to this goal. The present review discusses the associations between modifiable adverse factors and MCI/AD decline, MBI's impacts on adverse factors, and the mechanisms that could underlie the benefits of MBI. A schematic model is proposed to illustrate the course of neurodegeneration specific to MCI/AD, as well as the possible preventive mechanisms of MBI. Whereas regulation of glucocorticosteroids, inflammation, and serotonin could mediate MBI's effects on stress and depression, resolution of the metabolic syndrome might happen through a reduction of inflammation and white matter hyperintensities, and normalization of insulin and oxidation. The literature reviewed in this paper suggests that the main reach of MBI over MCI/AD development involves the management of stress, depressive symptoms, and inflammation. Future research must focus on achieving deeper understanding of MBI's mechanisms of action in the context of MCI and AD. This necessitates bridging the gap between neuroscientific subfields and a cross-domain integration between basic and clinical knowledge.

Analysis of verbal fluency ability in Alzheimer's disease: the role of clustering, switching and semantic proximities

The underlying nature of verbal fluency deficits in Alzheimer's disease (AD) was investigated in this study. Participants were 48 individuals with AD and 48 cognitively healthy older adults. Fluency performance on letter and category tasks was analyzed across two 30-s intervals for total words produced, mean cluster size, and total switches. Compared with the control group, AD participants produced fewer words and switches on both fluency tasks and had a reduced category cluster size. The AD group was differentially impaired on category compared with letter fluency and produced more repetitive responses but fewer category exemplars than controls on the category task. A multidimensional scaling approach revealed that AD participants' semantic maps were similar to controls. Overall, the data suggest that executive abilities involving search and retrieval processes and a reduced availability of semantically related words contributed to the AD group's poorer performance despite similar temporal recall and organizational patterns.

Communication Difficulty and Relevant Interventions in Mild Cognitive Impairment: Implications for Neuroplasticity

Mild Cognitive Impairment (MCI) represents a critical point for controlling cognitive decline. Patterns of communication difficulty have been observed in patients with MCI and warrant examination and management. The present systematic review examined (1) characteristics of communication difficulty in MCI by focusing on two domains: expressive and receptive communication, and (2) cognitive interventions that addressed communication difficulties in individuals with MCI. Of the 28 observational studies we reviewed, expressive and receptive communications were generally impaired in individuals with MCI, compared to their healthy counterparts. However, only one of seven interventions effectively improved communication related outcomes. We finished the paper with a discussion about how neuroplasticity influences communication abilities in individuals with MCI to inform the future development of interventions for communication difficulty.

Analysis of verbal fluency ability in amnestic and non-amnestic mild cognitive impairment

The purpose of this study was to investigate the pattern of performance on letter and category fluency tests of individuals with mild cognitive impairment (MCI). Previous research has suggested that organization strategies, including "clustering" (i.e., groups of related words) and "switching" (i.e., shift from one cluster to another), are important for efficient verbal fluency performance. Participants were 25 individuals with single-domain amnestic MCI (aMCI), 49 with multidomain aMCI, 16 with non-amnestic MCI (naMCI), and 90 cognitively healthy older adults. Fluency performances were analyzed across two 30-s intervals for total words produced, cluster size, and switching. Analyses of variance (ANOVAs) with follow-up tests revealed that the single-domain aMCI group performed comparably with healthy controls on each dependent measure across both fluency tasks. In contrast, the multidomain aMCI group showed performance decrements in total words and switching production compared with healthy controls on both fluency tasks, whereas the naMCI group produced fewer words and switches on letter fluency. Each group generated more words and switches during the first 30-s on both fluency tasks, with the exception of the naMCI group, whose switching on letter fluency did not decrease as the task progressed. As indicated by the single-domain aMCI group's unimpaired performance, our findings demonstrate that verbal fluency performance decreases as domains beyond memory become impaired in MCI. Reduced switching ability, which has been linked to prefrontal executive functioning, contributed the most to the poorer performance of individuals with multidomain MCI and naMCI.

Normal Cognitive Aging and Mild Cognitive Impairment: Drawing the Fine Line

Mild cognitive impairment (MCI) is a transitional diagnostic category between normal cognitive aging and dementia. Speech-language pathologists (SLPs) have a role in the management of MCI, particularly the assessment and treatment of cognitive-communicative impairments related to MCI. The difficulty lies in distinguishing between normal cognitive aging and pathological aging. SLPs will need to be equipped with knowledge regarding the neurobiological, cognitive, and cognitive-communicative changes occurring in both normal and pathological aging, specifically the alterations arising in MCI.

Does tip-of-the-tongue for proper names discriminate amnestic mild cognitive impairment?

BACKGROUND

Difficulty in retrieving people's names is very common in the early stages of Alzheimer's disease and mild cognitive impairment. Such difficulty is often observed as the tip-of-the-tongue (TOT) phenomenon. The main aim of this study was to explore whether a famous people's naming task that elicited the TOT state can be used to discriminate between amnestic mild cognitive impairment (aMCI) patients and normal controls.

METHODS

Eighty-four patients with aMCI and 106 normal controls aged over 50 years performed a task involving naming 50 famous people shown in pictures. Univariate and multivariate regression analyses were used to study the relationships between aMCI and semantic and phonological measures in the TOT paradigm.

RESULTS

Univariate regression analyses revealed that all TOT measures significantly predicted aMCI. Multivariate analysis of all these measures correctly classified 70% of controls (specificity) and 71.6% of aMCI patients (sensitivity), with an AUC (area under curve ROC) value of 0.74, but only the phonological measure remained significant. This classification value was similar to that obtained with the Semantic verbal fluency test.

CONCLUSIONS

TOTs for proper names may effectively discriminate aMCI patients from normal controls through measures that represent one of the naming processes affected, that is, phonological access.

Voxel-wise co-analysis of macro- and microstructural brain alteration in mild cognitive impairment and Alzheimer's disease using anatomical and diffusion MRI

BACKGROUND AND PURPOSE

To determine if a voxel-wise "co-analysis" of structural and diffusion tensor magnetic resonance imaging (MRI) together reveals additional brain regions affected in mild cognitive impairment (MCI) and Alzheimer's disease (AD) than voxel-wise analysis of the individual MRI modalities alone.

METHODS

Twenty-one patients with MCI, 21 patients with AD, and 21 cognitively normal healthy elderly were studied with MRI. Maps of deformation and fractional anisotropy (FA) were computed and used as dependent variables in univariate and multivariate statistical models.

RESULTS

Univariate voxel-wise analysis of macrostructural changes in MCI showed atrophy in the right anterior temporal lobe, left posterior parietal/precuneus region, WM adjacent to the cingulate gyrus, and dorsolateral prefrontal regions, consistent with prior research. Univariate voxel-wise analysis of microstructural changes in MCI showed reduced FA in the left posterior parietal region extending into the corpus callosum, consistent with previous work. The multivariate analysis, which provides more information than univariate tests when structural and FA measures are correlated, revealed additional MCI-related changes in corpus callosum and temporal lobe.

CONCLUSION

These results suggest that in corpus callosum and temporal regions macro- and microstructural variations in MCI can be congruent, providing potentially new insight into the mechanisms of brain tissue degeneration.

Semantic memory and language dysfunction in early Alzheimer's disease: a review

BACKGROUND

Language impairment in Alzheimer's disease occurs early, and language function deteriorates with progression of the illness to cause significant disability. This review focuses on language dysfunction in Alzheimer's disease and the contribution of semantic memory impairment.

METHODS

Electronic publication databases were searched for literature relevant to the review. Additionally, individual references were examined to elicit further studies not found by online search.

RESULTS

Language impairment in Alzheimer's disease initially affects verbal fluency and naming before breakdown in other facets. Naming and fluency require integrity of semantic concepts, and dysfunction may be a marker of primary semantic memory impairment rather than overall cognitive decline. Research suggests the presence of semantic loss several years prior to diagnosis. Imaging studies indicate an altered connectivity state with respect to language networks, and this is associated with potential semantic failure. This state may also be present in individuals with established risk factors for Alzheimer's disease. Compensatory recruitment of alternative cortical areas to supplement language function appears to occur and may be a target for future intervention.

CONCLUSIONS

Identifying and classifying the nature and degree of language impairment more closely could aid in developing targeted therapies. Treatments already established in other aphasic states, such as post-stroke, may be especially relevant. The nature of these and the protective nature of cognitive reserve are potential therapeutic avenues.

Grammar learning in older adults is linked to white matter microstructure and functional connectivity

Age-related decline in cognitive function has been linked to alterations of white matter and functional brain connectivity. With regard to language, aging has been shown to be associated with impaired syntax processing, but the underlying structural and functional correlates are poorly understood. In the present study, we used an artificial grammar learning (AGL) task to determine the ability to extract grammatical rules from new material in healthy older adults. White matter microstructure and resting-state functional connectivity (FC) of task-relevant brain regions were assessed using multimodal magnetic resonance imaging (MRI). AGL performance correlated positively with fractional anisotropy (FA) underlying left and right Brodmann areas (BA) 44/45 and in tracts originating from left BA 44/45. An inverse relationship was found between task performance and FC of left and right BA 44/45, linking lower performance to stronger inter-hemispheric functional coupling. Our results suggest that white matter microstructure underlying specific prefrontal regions and their functional coupling affect acquisition of syntactic knowledge in the aging brain, offering further insight into mechanisms of functional decline in older adults.

Alzheimer's pathology in primary progressive aphasia

Primary progressive aphasia (PPA) is a neurodegenerative disorder with language impairment as the primary feature. Different subtypes have been described and the 3 best characterized are progressive nonfluent aphasia (PNFA), semantic dementia (SD) and logopenic/phonological aphasia (LPA). Of these subtypes, LPA is most commonly associated with Alzheimer's disease (AD) pathology. However, the features of PPA associated with AD have not been fully defined. Here we retrospectively identified 14 patients with PPA and either pathologically confirmed AD or cerebrospinal fluid (CSF) biomarkers consistent with AD. Analysis of neurological and neuropsychological features revealed that all patients had a syndrome of LPA with relatively nonfluent spontaneous speech, phonemic errors, and reduced digit span; most patients also had impaired verbal episodic memory. Analysis of the pattern of cortical thinning in these patients revealed left posterior superior temporal, inferior parietal, medial temporal, and posterior cingulate involvement and in patients with more severe disease, increasing involvement of left anterior temporal and frontal cortices and right hemisphere areas in the temporo-parietal junction, posterior cingulate, and medial temporal lobe. We propose that LPA may be a "unihemispheric" presentation of AD, and discuss this concept in relation to accumulating evidence concerning language dysfunction in AD.

Autonomic responses to pain in aging and dementia

Increasing age and dementia are accompanied by an increased risk for undertreatment of pain owing to difficulty in assessing pain. Registration of autonomic responses to pain may contribute to a more reliable pain assessment. The aim of this review was to gain more insight into autonomic responses to pain in older persons with and without dementia. Literature searches were performed in the online databases MEDLINE and Web of Science. Seven studies on autonomic responses to pain in older people with or without dementia were included in the review. Autonomic responses to pain are present in older people with and without dementia, although they may be attenuated. Because no distinction could be made between different dementia subtypes based on these studies, predictions of changes in autonomic responses to pain have been made based on neuropathological changes. It can be concluded that autonomic responses to pain are attenuated in older people with and without dementia. Studies to specify the changes in the different autonomic responses for the different dementia subtypes are needed.

Age-related impairment of ultrasonic vocalization in Tau.P301L mice: possible implication for progressive language disorders

Background

Tauopathies, including Alzheimer's Disease, are the most frequent neurodegenerative diseases in elderly people and cause various cognitive, behavioural and motor defects, but also progressive language disorders. For communication and social interactions, mice produce ultrasonic vocalization (USV) via expiratory airflow through the larynx. We examined USV of Tau.P301L mice, a mouse model for tauopathy expressing human mutant tau protein and developing cognitive, motor and upper airway defects.

Methodology/Principal Findings

At age 4–5 months, Tau.P301L mice had normal USV, normal expiratory airflow and no brainstem tauopathy. At age 8–10 months, Tau.P301L mice presented impaired USV, reduced expiratory airflow and severe tauopathy in the periaqueductal gray, Kolliker-Fuse and retroambiguus nuclei. Tauopathy in these nuclei that control upper airway function and vocalization correlates well with the USV impairment of old Tau.P301L mice.

Conclusions

In a mouse model for tauopathy, we report for the first time an age-related impairment of USV that correlates with tauopathy in midbrain and brainstem areas controlling vocalization. The vocalization disorder of old Tau.P301L mice could be, at least in part, reminiscent of language disorders of elderly suffering tauopathy.

The Cognitive Assessment Battery (CAB): a rapid test of cognitive domains

BACKGROUND

The study aimed to evaluate the Cognitive Assessment Battery (CAB) in a specialist clinic setting in order to find out if it if it could be a supplement to the Mini-mental State Examination (MMSE) and distinguish between normal aging, mild cognitive impairment (MCI) and dementia, as well as MCI of different severities.

METHODS

CAB consists of six short tests covering the cognitive domains of speed/attention, episodic memory, visuospatial functions, language and executive functions. It takes about 20 minutes to carry out and provides a quick overview of the patient's cognitive profile. Three groups were compared: healthy controls (N = 41), MCI (N = 83) and mild dementia (N = 28).

RESULTS

CAB distinguished very clearly between controls and MCI as well as MCI and dementia. On further analysis CAB also distinguished between MCI of different severities. It also showed to have good sensitivity and specificity for identifying more severe MCI.

CONCLUSIONS

CAB seems to be a useful supplement to MMSE and a screening instrument for MCI and dementia with good sensitivity and specificity.

Capacity of the Catalan and Spanish versions of the Bilingual Aphasia Test to distinguish between healthy aging, mild cognitive impairment and Alzheimer's disease

This study analysed the capacity of the Catalan and Spanish versions of the Bilingual Aphasia Test (BAT) to distinguish between normal and pathological aging. Both versions of the test were administered to 45 bilingual subjects: 15 healthy aging subjects, 15 patients with mild cognitive impairment and 15 patients with Alzheimer's disease. To explore which combination of subtests was best suited to differentiate the three study groups, stepwise discriminant analyses were performed using each version of the Bilingual Aphasia Test separately and together. The percentages of properly classified subjects were as follows: 93.3% when the Spanish version was administered, 88.9% when the Catalan version was administered and 95.6% when both versions were used. The subtests that best classified the subjects were of the lexical-semantic type but also related to metalinguistic capacity and language organisation skills. The performance of each group in Catalan and Spanish was more similar than different.

Cognitive intervention for persons with mild cognitive impairment: A meta-analysis

Cognitive training for persons with mild cognitive impairment (MCI) has become a hot topic. However to date it remains controversial whether persons with MCI can really benefit from cognitive intervention. We aim to further investigate this by using meta-analysis of seventeen clinical studies of cognitive intervention for MCI. The results demonstrate that after training, patients with MCI improve significantly both in overall cognition and overall self-ratings. Specifically, persons with MCI obtain moderate benefits in language, self-rated anxiety and functional ability, and receive mild benefits in episodic memory, semantic memory, executive functioning/working memory, visuo-spatial ability, attention/processing speed, MMSE, self-rated memory problem, quality of life, activities of daily life and self-rated depression. The results also suggest that persons with MCI benefit from the cognitive intervention in the follow-up data. The present meta-analysis demonstrates that cognitive intervention can be a potential efficient method to enhance cognitive and functional abilities in persons with MCI, although the improvements may be domain-specific.

Performance on a measure of category fluency in cognitively impaired elderly

Measures of verbal fluency are widely used in the assessment of cognitive functioning of the elderly. However, limited research has evaluated patterns (across specific timed intervals) of performance on tasks of language fluency in different forms of dementia. The current study investigated semantic fluency in 488 elderly individuals (249 with Alzheimer's dementia, 97 Vascular dementia, 97 Mild Cognitive Impairment and 45 cognitively intact) across 15-second intervals in an animal naming task using retrospective chart review. Normal controls produced significantly more exemplars and AD patients produced fewer animal names than the other groups. After the first 15- second time interval, the demented groups produced significantly fewer exemplars than the non-demented. At the end of 30 seconds it was possible to differentiate normal aging from MCI who no longer differed from the VaD group. Overall, it appears that the greatest and most clinically meaningful differences between the diagnostic groups were detected in the first three 15-second intervals. The present findings support the use of time intervals and total scores on tasks of verbal fluency in clinical settings and for research purposes.

Nonliteral language in Alzheimer dementia: a review

The use of nonliteral language in clinical assessment, especially testing the patients' ability to interpret proverbs, has a long tradition in psychiatry. However, its diagnostic sensitivity and specificity in dementias is not yet clear. The aim of this review article is to examine the current evidence on nonliteral/figurative language (proverb, metaphor, metonymy, idiom, irony, sarcasm) comprehension in Alzheimer's disease and related disorders. A comprehensive literature search identified 25 studies (16 proverb, 3 metaphor, 0 metonymy, 5 idiom, 3 sarcasm) on nonliteral language comprehension in dementia. Studies predominantly indicate a deficit. Most studies investigated Alzheimer's dementia. Applied correctly, nonliteral language is a worthwhile diagnostic tool to evaluate language and abstract thinking in dementias. During assessment, familiarity testing (e.g., by asking "are you familiar with the proverb XY") is obligatory. Still, future research is needed in several areas: evidence on decline of nonliteral language over the course of the illness is limited. So far, almost no studies delineated proverb comprehension in high risk populations such as patients with mild cognitive impairment. Currently, there is a lack of studies addressing performance in direct comparison to relevant differential diagnosis like older-age depression, delirium, brain lesion, or other psychiatric conditions.

Emotional prosody perception and production in dementia of the Alzheimer's type

PURPOSE

In this study, the authors investigated emotional prosody in patients with moderate Dementia of the Alzheimer's type (DAT) With Late Onset. It was expected that both expression and reception of prosody would be impaired relative to age-matched controls.

METHOD

Twenty DAT and 20 control participants engaged in 2 expressive and 2 receptive tasks with randomly presented exemplars of sentences targeting the emotions of happiness, anger, sadness, and surprise.

RESULTS

In the expressive tasks, objective acoustic measurements revealed significantly less pitch modulation by the patient group, but these measurements showed that they retained the ability to vary pitch level, pitch modulation, and speaking rate as a function of emotion. In the receptive tasks, perception of emotion by the patient group was significantly inferior to the control group.

CONCLUSIONS

Implications are discussed regarding impaired emotional prosody in DAT, and the utility of objective acoustic measures in revealing subtle deficits and overcoming methodological inconsistencies is emphasized. Further research is critical in advancing our understanding of this pervasive disorder and is important, clinically, in the provision of specific interventions.

Propositional density and cognitive function in later life: findings from the Precursors Study

OBJECTIVES

We used longitudinal data from the Johns Hopkins Precursors Study to test the hypothesis that written propositional density measured early in life is lower for people who develop dementia categorized as Alzheimer's disease (AD). This association was reported in 1996 for the Nun Study, and the Precursors Study offered an unprecedented chance to reexamine it among respondents with different gender, education, and occupation profiles.

METHODS

Eighteen individuals classified as AD patients (average age at diagnosis: 74) were assigned 2 sex-and-age matched controls, and propositional density in medical school admission essays (average age at writing: 22) was assessed via Computerized Propositional Idea Density Rater 3 linguistic analysis software. Adjusted odds ratios (ORs) for the matched case-control study were calculated using conditional (fixed-effects) logistic regression.

RESULTS

Mean propositional density is lower for cases than for controls (4.70 vs. 4.99 propositions per 10 words, 1-sided p = .01). Higher propositional density substantially lowers the odds of AD (OR = 0.16, 95% confidence interval = 0.03-0.90, 1-sided p = .02).

DISCUSSION

Propositional density scores in writing samples from early adulthood appear to predict AD in later life for men as well as women. Studies of cognition across the life course might beneficially incorporate propositional density as a potential marker of cognitive reserve.

Relationship between regional atrophy rates and cognitive decline in mild cognitive impairment

We investigated the relationship between regional atrophy rates and 2-year cognitive decline in a large cohort of patients with mild cognitive impairment (MCI; n = 103) and healthy controls (n = 90). Longitudinal magnetic resonance image (MRI) scans were analyzed using high-throughput image analysis procedures. Atrophy rates were derived by calculating percent cortical volume loss between baseline and 24 month scans. Stepwise regressions were performed to investigate the contribution of atrophy rates to language, memory, and executive functioning decline, controlling for age, gender, baseline performances, and disease progression. In MCI, left temporal lobe atrophy rates were associated with naming decline, whereas bilateral temporal, left frontal, and left anterior cingulate atrophy rates were associated with semantic fluency decline. Left entorhinal atrophy rate was associated with memory decline and bilateral frontal atrophy rates were associated with executive function decline. These data provide evidence that regional atrophy rates in MCI contribute to domain-specific cognitive decline, which appears to be partially independent of disease progression. MRI measures of regional atrophy can provide valuable information for understanding the neural basis of cognitive impairment in MCI.

Progressive logopenic/phonological aphasia: erosion of the language network

The primary progressive aphasias (PPA) are paradigmatic disorders of language network breakdown associated with focal degeneration of the left cerebral hemisphere. Here we addressed brain correlates of PPA in a detailed neuroanatomical analysis of the third canonical syndrome of PPA, logopenic/phonological aphasia (LPA), in relation to the more widely studied clinico-anatomical syndromes of semantic dementia (SD) and progressive nonfluent aphasia (PNFA). 32 PPA patients (9 SD, 14 PNFA, 9 LPA) and 18 cognitively normal controls had volumetric brain MRI with regional volumetry, cortical thickness, grey and white matter voxel-based morphometry analyses. Five of nine patients with LPA had cerebrospinal fluid biomarkers consistent with Alzheimer (AD) pathology (AD-PPA) and 2/9 patients had progranulin (GRN) mutations (GRN-PPA). The LPA group had tissue loss in a widespread left hemisphere network. Compared with PNFA and SD, the LPA group had more extensive involvement of grey matter in posterior temporal and parietal cortices and long association white matter tracts. Overlapping but distinct networks were involved in the AD-PPA and GRN-PPA subgroups, with more anterior temporal lobe involvement in GRN-PPA. The importance of these findings is threefold: firstly, the clinico-anatomical entity of LPA has a profile of brain damage that is complementary to the network-based disorders of SD and PNFA; secondly, the core phonological processing deficit in LPA is likely to arise from temporo-parietal junction damage but disease spread occurs through the dorsal language network (and in GRN-PPA, also the ventral language network); and finally, GRN mutations provide a specific molecular substrate for language network dysfunction.

Multiple cognitive deficits in patients during the mild cognitive impairment stage of Alzheimer's disease: how are cognitive domains other than episodic memory impaired?

BACKGROUND

Little is known about how cognitive domains other than episodic memory are affected during the mild cognitive impairment (MCI) stage of Alzheimer's disease (AD). We attempted to clarify this issue in this study.

METHODS

Fifty-seven Japanese subjects were divided into two groups: one comprising people in the MCI stage of AD (MCI group, n = 28) and the other of normal controls (NC group, n = 29). Cognitive functions were assessed using the Japanese version of the neurobehavioral cognitive status examination (J-COGNISTAT).

RESULTS

The MCI group performed significantly worse than the NC group on subtests that assessed orientation, confrontational naming, constructive ability, episodic memory, and abstract thinking. Three-quarters of the MCI group had deficits in memory and other non-mnemonic domains, particularly constructive ability and abstract thinking. However, within-subject comparisons showed that the MCI group performed significantly worse on the memory subtest compared to any other subtest.

CONCLUSIONS

Besides episodic memory, multiple non-mnemonic cognitive domains, such as constructive ability and abstract thinking, are also impaired during the MCI stage of AD; however, these non-mnemonic deficits are smaller than episodic memory impairment.

Longitudinal verbal fluency in normal aging, preclinical, and prevalent Alzheimer's disease

BACKGROUND

Few longitudinal studies evaluate differences in patterns of change of category compared to letter fluency across the spectrum of cognitive impairment.

METHODS

We compared change in category (animal and supermarket) and letter (F, A, S) fluency among 239 participants in 3 groups: remained cognitively normal throughout follow-up (n = 96), developed Alzheimer's Disease (AD; preclinical AD, n = 21), and with AD at initial testing (prevalent AD, n = 122).

RESULTS

At baseline, prevalent and preclinical AD groups scored lower on animal than letter fluency. On all fluency measures, the prevalent AD declined faster than other groups (all P < .0001), and preclinical AD declined faster than unimpaired (all P <or= .02). Overall, animal fluency declined faster than letter fluency; animal fluency declined significantly faster than letter fluency among cognitively normal and prevalent AD participants.

CONCLUSION

Greater longitudinal declines in category compared to letter fluency are consistent with cross-sectional studies. Steeper declines on both fluency measures distinguish preclinical AD from cognitively unimpaired individuals.