Aphasia in senile dementia of the Alzheimer type

Cognitive components of aging-related increase in word-finding difficulty

Word-finding difficulty (WFD) is a common cognitive complaint in aging, manifesting both in natural speech and in controlled laboratory tests. Various theories of cognitive aging have addressed WFD, and understanding its underlying mechanisms can help to clarify whether it has diagnostic value for neurodegenerative disease. Two influential "information-universal" theories attribute it to rather broad changes in cognition. The processing speed theory posits a general slowdown of all cognitive processes, while the inhibitory deficit hypothesis (IDH) predicts a specific problem in suppressing irrelevant information. One "information specific" theory of language production, the transmission deficit hypothesis (TDH), posits a breakdown in retrieval of phonological word forms from a corresponding lemma. To adjudicate between these accounts, we administered an online gamified covert naming task featuring picture-word interference (PWI), previously validated to elicit similar semantic interference and phonological facilitation effects as overt naming tasks. 125 healthy adults aged 18 to 85 completed the task, along with a battery of executive function tasks and a naturalistic speech sample to quantify WFD in connected speech. PWI effects provided strong support for the TDH but limited support for IDH, in that semantic interference increased and phonological facilitation decreased across the lifespan. However, neither of these effects on single-word retrieval associated with WFD measured in connected speech. Rather, overall reaction time for word retrieval (controlling for psychomotor slowing) was the best predictor of spontaneous WFD and executive function decline, suggesting processing speed as the key factor, and that verbal reaction time may be an important clinical measure.

Identifying neurocognitive disorder using vector representation of free conversation

In recent years, studies on the use of natural language processing (NLP) approaches to identify dementia have been reported. Most of these studies used picture description tasks or other similar tasks to encourage spontaneous speech, but the use of free conversation without requiring a task might be easier to perform in a clinical setting. Moreover, free conversation is unlikely to induce a learning effect. Therefore, the purpose of this study was to develop a machine learning model to discriminate subjects with and without dementia by extracting features from unstructured free conversation data using NLP. We recruited patients who visited a specialized outpatient clinic for dementia and healthy volunteers. Participants’ conversation was transcribed and the text data was decomposed from natural sentences into morphemes by performing a morphological analysis using NLP, and then converted into real-valued vectors that were used as features for machine learning. A total of 432 datasets were used, and the resulting machine learning model classified the data for dementia and non-dementia subjects with an accuracy of 0.900, sensitivity of 0.881, and a specificity of 0.916. Using sentence vector information, it was possible to develop a machine-learning algorithm capable of discriminating dementia from non-dementia subjects with a high accuracy based on free conversation.

A study of using cough sounds and deep neural networks for the early detection of Covid-19

The current clinical diagnosis of COVID-19 requires person-to-person contact, needs variable time to produce results, and is expensive. It is even inaccessible to the general population in some developing countries due to insufficient healthcare facilities. Hence, a low-cost, quick, and easily accessible solution for COVID-19 diagnosis is vital. This paper presents a study that involves developing an algorithm for automated and noninvasive diagnosis of COVID-19 using cough sound samples and a deep neural network. The cough sounds provide essential information about the behavior of glottis under different respiratory pathological conditions. Hence, the characteristics of cough sounds can identify respiratory diseases like COVID-19. The proposed algorithm consists of three main steps (a) extraction of acoustic features from the cough sound samples, (b) formation of a feature vector, and (c) classification of the cough sound samples using a deep neural network. The output from the proposed system provides a COVID-19 likelihood diagnosis. In this work, we consider three acoustic feature vectors, namely (a) time-domain, (b) frequency-domain, and (c) mixed-domain (i.e., a combination of features in both time-domain and frequency-domain). The performance of the proposed algorithm is evaluated using cough sound samples collected from healthy and COVID-19 patients. The results show that the proposed algorithm automatically detects COVID-19 cough sound samples with an overall accuracy of 89.2%, 97.5%, and 93.8% using time-domain, frequency-domain, and mixed-domain feature vectors, respectively. The proposed algorithm, coupled with its high accuracy, demonstrates that it can be used for quick identification or early screening of COVID-19. We also compare our results with that of some state-of-the-art works.

Rationale and study design of a randomized, placebo-controlled, double-blind phase 2b trial to evaluate efficacy, safety, and tolerability of an oral glutaminyl cyclase inhibitor varoglutamstat (PQ912) in study participants with MCI and mild AD-VIVIAD

BACKGROUND

Varoglutamstat (formerly PQ912) is a small molecule that inhibits the activity of the glutaminyl cyclase to reduce the level of pyroglutamate-A-beta (pGluAB42). Recent studies confirm that pGluAB42 is a particular amyloid form that is highly synaptotoxic and plays a significant role in the development of AD.

METHODS

This paper describes the design and methodology behind the phase 2b VIVIAD-trial in AD. The aim of this study is to evaluate varoglutamstat in a state-of-the-art designed, placebo-controlled, double-blind, randomized clinical trial for safety and tolerability, efficacy on cognition, and effects on brain activity and AD biomarkers. In addition to its main purpose, the trial will explore potential associations between novel and established biomarkers and their individual and composite relation to disease characteristics.

RESULTS

To be expected early 2023 CONCLUSION: This state of the art phase 2b study will yield important results for the field with respect to trial methodology and for the treatment of AD with a small molecule directed against pyroglutamate-A-beta.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04498650.

Connected Speech Deficit as an Early Hallmark of CSF-defined Alzheimer's Disease and Correlation with Cerebral Hypoperfusion Pattern

BACKGROUND

Diagnosis of prodromal Alzheimer's disease (AD) still represents a hot topic and there is a growing interest for the detection of early and non-invasive biomarkers. Although progressive episodic memory impairment is the typical predominant feature of AD, communicative difficulties can be already present at the early stages of the disease.

OBJECTIVE

This study investigated the narrative discourse production deficit as a hallmark of CSFdefined prodromal AD and its correlation with cerebral hypoperfusion pattern.

METHODS

Narrative assessment with a multilevel procedure for discourse analysis was conducted on 28 subjects with Mild Cognitive Impairment (15 MCI due to AD; 13 MCI non-AD) and 28 healthy controls. The diagnostic workup included CSF AD biomarkers. Cerebral hypoperfusion pattern was identified by SPECT image processing.

RESULTS

The results showed that the discourse analysis of global coherence and lexical informativeness indexes allowed to identify MCI due to AD from MCI non-AD and healthy subjects. These findings allow to hypothesize that the loss of narrative efficacy could be a possible early clinical hallmark of Alzheimer's disease. Furthermore, a significant correlation of global coherence and lexical informativeness reduction with the SPECT hypoperfusion was found in the dorsal aspect of the anterior part of the left inferior frontal gyrus, supporting the hypothesis that this area has a significant role in communicative efficacy, and in particular, in semantic selection executive control.

CONCLUSION

This study contributes to the understanding of the neural networks for language processing and their involvement in prodromal Alzheimer's disease. It also suggests an easy and sensitive tool for clinical practice that can help identifying individuals with prodromal Alzheimer's disease.

How to do things with (thousands of) words: Computational approaches to discourse analysis in Alzheimer's disease

Natural Language Processing (NLP) is an ever-growing field of computational science that aims to model natural human language. Combined with advances in machine learning, which learns patterns in data, it offers practical capabilities including automated language analysis. These approaches have garnered interest from clinical researchers seeking to understand the breakdown of language due to pathological changes in the brain, offering fast, replicable and objective methods. The study of Alzheimer's disease (AD), and preclinical Mild Cognitive Impairment (MCI), suggests that changes in discourse (connected speech or writing) may be key to early detection of disease. There is currently no disease-modifying treatment for AD, the leading cause of dementia in people over the age of 65, but detection of those at risk of developing the disease could help with the identification and testing of medications which can take effect before the underlying pathology has irreversibly spread. We outline important components of natural language, as well as NLP tools and approaches with which they can be extracted, analysed and used for disease identification and risk prediction. We review literature using these tools to model discourse across the spectrum of AD, including the contribution of machine learning approaches and Automatic Speech Recognition (ASR). We conclude that NLP and machine learning techniques are starting to greatly enhance research in the field, with measurable and quantifiable language components showing promise for early detection of disease, but there remain research and practical challenges for clinical implementation of these approaches. Challenges discussed include the availability of large and diverse datasets, ethics of data collection and sharing, diagnostic specificity and clinical acceptability.

The Level of NMDA Receptor in the Membrane Modulates Amyloid-β Association and Perforation

Alzheimer's disease is a neurodegenerative disorder that affects mostly the elderly. The main histopathological markers are the senile plaques formed by amyloid-β peptide (Aβ) aggregates that can perforate the plasma membrane of cells, increasing the intracellular calcium levels and releasing synaptic vesicles that finally lead to a delayed synaptic failure. Several membrane proteins and lipids interact with Aβ affecting its toxicity in neurons. Here, we focus on NMDA receptors (NMDARs) as proteins that could be modulating the association and neurotoxic perforation induced by Aβ on the plasma membrane. In fact, our results showed that decreasing NMDARs, using enzymatic or siRNA approaches, increased the association of Aβ to the neurons. Furthermore, overexpression of NMDARs also resulted in an enhanced association between NMDA and Aβ. Functionally, the reduction in membrane NMDARs augmented the process of membrane perforation. On the other hand, overexpressing NMDARs had a protective effect because Aβ was now unable to cause membrane perforation, suggesting a complex relationship between Aβ and NMDARs. Because previous studies have recognized that Aβ oligomers are able to increase membrane permeability and produce amyloid pores, the present study supports the conclusion that NMDARs play a critical protective role on Aβ actions in hippocampal neurons. These results could explain the lack of correlation between brain Aβ burden and clinically observed dementia.

Connected Language in Late Middle-Aged Adults at Risk for Alzheimer's Disease

Connected language is often impaired among people with Alzheimer's disease (AD), yet little is known about when language difficulties first emerge on the path to a clinical diagnosis. The objective of this study was to determine whether individuals with psychometric (preclinical) evidence of amnestic mild cognitive impairment (pMCI) showed deficits in connected language measures. Participants were 39 pMCI and 39 cognitively healthy (CH) adults drawn from the Wisconsin Registry for Alzheimer's Prevention, who were matched for age, literacy, and sex. Participants completed a connected language task in which they described the Cookie Theft picture from the Boston Diagnostic Aphasia Examination. Language samples were analyzed across three language domains: content, syntactic complexity, and speech fluency. Paired t-tests were used to compare CH and pMCI groups on all variables, and Cohen's d effect sizes were calculated for each comparison. The CH and pMCI groups differed significantly on measures of content (e.g., CH group produced more semantic units, more unique words and had larger idea density, on average, than the pMCI group). The picture description findings are consistent with previous retrospective studies showing semantic language differences in adults with autopsy-confirmed AD. Given that these comparisons are between cognitively healthy and pMCI individuals (before a clinical MCI diagnosis), these findings may represent subtle language difficulty in spontaneous speech, and may be predictive of larger language changes over time.

Linguistic Features Identify Alzheimer's Disease in Narrative Speech

BACKGROUND

Although memory impairment is the main symptom of Alzheimer's disease (AD), language impairment can be an important marker. Relatively few studies of language in AD quantify the impairments in connected speech using computational techniques.

OBJECTIVE

We aim to demonstrate state-of-the-art accuracy in automatically identifying Alzheimer's disease from short narrative samples elicited with a picture description task, and to uncover the salient linguistic factors with a statistical factor analysis.

METHODS

Data are derived from the DementiaBank corpus, from which 167 patients diagnosed with "possible" or "probable" AD provide 240 narrative samples, and 97 controls provide an additional 233. We compute a number of linguistic variables from the transcripts, and acoustic variables from the associated audio files, and use these variables to train a machine learning classifier to distinguish between participants with AD and healthy controls. To examine the degree of heterogeneity of linguistic impairments in AD, we follow an exploratory factor analysis on these measures of speech and language with an oblique promax rotation, and provide interpretation for the resulting factors.

RESULTS

We obtain state-of-the-art classification accuracies of over 81% in distinguishing individuals with AD from those without based on short samples of their language on a picture description task. Four clear factors emerge: semantic impairment, acoustic abnormality, syntactic impairment, and information impairment.

CONCLUSION

Modern machine learning and linguistic analysis will be increasingly useful in assessment and clustering of suspected AD.

Early-onset and late-onset Alzheimer's disease are associated with distinct patterns of memory impairment

The goal of this study was to investigate the specific patterns of memory breakdown in patients suffering from early-onset Alzheimer's disease (EOAD) and late-onset Alzheimer's disease (LOAD). Twenty EOAD patients, twenty LOAD patients, twenty matched younger controls, and twenty matched older controls participated in this study. All participants underwent a detailed neuropsychological assessment, an MRI scan, an FDG-PET scan, and AD patients had biomarkers as supporting evidence of both amyloïdopathy and neuronal injury. Results of the neuropsychological assessment showed that both EOAD and LOAD groups were impaired in the domains of memory, executive functions, language, praxis, and visuoconstructional abilities, when compared to their respective control groups. EOAD and LOAD groups, however, showed distinct patterns of memory impairment. Even though both groups were similarly affected on measures of episodic, short term and working memory, in contrast semantic memory was significantly more impaired in LOAD than in EOAD patients. The EOAD group was not more affected than the LOAD group in any memory domain. EOAD patients, however, showed significantly poorer performance in other cognitive domains including executive functions and visuoconstructional abilities. A more detailed analysis of the pattern of semantic memory performance among patient groups revealed that the LOAD was more profoundly impaired, in tasks of both spontaneous recall and semantic recognition. Voxel-Based Morphometry (VBM) analyses showed that impaired semantic performance in patients was associated with reduced gray matter volume in the anterior temporal lobe (ATL) region, while PET-FDG analyses revealed that poorer semantic performance was associated with greater hypometabolism in the left temporoparietal region, both areas reflecting key regions of the semantic network. Results of this study indicate that EOAD and LOAD patients present with distinct patterns of memory impairment, and that a genuine semantic impairment may represent one of the clinical hallmarks of LOAD.

Risk Factors for Progression of Alzheimer Disease in a Canadian Population: The Canadian Outcomes Study in Dementia (COSID)

OBJECTIVE

To determine risk factors for clinically significant progression during 12 months in patients with mild-to-moderate Alzheimer disease.

METHOD

Community-dwelling patients with mild-to-moderate Alzheimer disease were enrolled in a 3-year prospective study, the Canadian Outcomes Study in Dementia (commonly referred to as COSID), at 32 Canadian sites. Assessments included the Global Deterioration Scale (GDS) for disease severity, the Mini-Mental State Examination (MMSE) for cognition, the Functional Autonomy Measurement System (SMAF) for daily functioning, and the NeuroPsychiatric Inventory (NPI) for behaviour, measured at baseline and at 12 months. Logistic regression identified factors associated with GDS decline, and subsequent stepwise regression identified key independent predictors. Area under the curve (AUC) was then calculated for the model.

RESULTS

Among 488 patients (mean age 76.5 years [SD 6.4], MMSE 22.1 [SD4.6], 44.1% male), 225 (46%) showed GDS decline. After adjusting for age, baseline risk factors for deterioration included the following: poorer cognition (lower MMSE score, OR 0.55; 95% CI 0.4 to 0.72 per 5 points, P ≤ 0.001), greater dependence (lower SMAF, OR 0.72; 95% CI 0.63 to 0.83 per 5 points, P ≤ 0.001), and more neuropsychiatric symptoms (higher NPI, OR 1.11; 95% CI 1.02 to 1.2 per 5 points, P = 0.02), with a protective effect of male sex (OR 0.59; 95% CI 0.39 to 0.9, P = 0.02), and higher (worse) GDS score (very mild, compared with mild OR 0.25; 95% CI 0.09 to 0.70, P ≤ 0.01; compared with moderate, OR 0.08; 95% CI 0.03 to 0.23, P < 0.001; compared with moderately severe, OR 0.03; 95% CI 0.01 to 0.11, P < 0.001). The AUC was 73% (P < 0.001) (sensitivity 90% and specificity 33%).

CONCLUSION

The progression of Alzheimer disease in Canada can be predicted using readily available clinical information.

Charting the decline in spontaneous writing in Alzheimer's disease: a longitudinal study

OBJECTIVE

This study aims to document the nature and progression of the spontaneous writing impairment observed in patients with Alzheimer's disease (AD) over a 12-month period using both a cross-sectional and prospective longitudinal design.

METHODS

Thirty-one minimal-moderate AD patients and 30 controls matched for age and socio-cultural background completed a simple and complex written description task at baseline. The AD patients then had follow-up assessments at 6 and 12 months.

RESULTS

Cross-sectional comparisons indicated that minimal-moderate AD patients produced more semantic paraphasias, phonological paraphasias, and empty and indefinite phrases, whilst producing fewer pictorial themes, repairing fewer errors, and producing shorter and less complex sentences than controls. The two groups could not be distinguished on visual paraphasias. Longitudinal follow-up, however, suggested that visual processing deteriorates over time, where the prevalence of visual errors increased over 12 months. Discussion The findings suggest that the deterioration of writing skills observed in the spontaneous writings of AD patients shows a pattern of impairment dominated by semantic errors with a secondary impairment in phonological processing, which is later joined by a disruption of visuospatial and graphomotor processing.

Profiling spontaneous speech decline in Alzheimer's disease: a longitudinal study

OBJECTIVE

This study aims to document the nature and progression of spontaneous speech impairment suffered by patients with Alzheimer's disease (AD) over a 12-month period, using both cross-sectional and prospective longitudinal design.

METHODS

Thirty one mild-moderate AD patients and 30 controls matched for age and socio-cultural background completed a simple and complex oral description task at baseline. The AD patients then underwent follow-up assessments at 6 and 12 months.

RESULTS

Cross-sectional comparisons indicated that mild-moderate AD patients produced more word-finding delays (WFDs) and empty and indefinite phrases, while producing fewer pictorial themes, repairing fewer errors, responding to fewer WFDs, produce shorter and less complex phrases and produce speech with less intonational contour than controls. However, the two groups could not be distinguished on the basis of phonological paraphasias. Longitudinal follow-up, however, suggested that phonological processing deteriorates over time, where the prevalence of phonological errors increased over 12 months. Discussion Consistent with findings from neuropsychological, neuropathological and neuroimaging studies, the language deterioration shown by the AD patients shows a pattern of impairment dominated by semantic errors, which is later joined by a disruption in the phonological aspects of speech.

Neuropsychology of Alzheimer's disease

The expression of neurodegenerative diseases can be categorized into three main symptomatic domains: neurological, cognitive and, neuropsychiatric. This review focuses on the cognitive profile and neuropsychological assessment of Alzheimer's disease (AD). The topography and progression of brain neuropathology determines the cognitive expression of the disease. Thus, in accordance with the initial involvement of the medial temporal lobe, cognitive changes in AD start with specific difficulties in encoding and storage of new information. This particular memory deficit can be optimally detected with memory tests that enhance mnemonic retrieval by means of encoding specificity technique such as the Free and Cued Selective Reminding Test (FCSRT). Along the course of the disease, the neuropathology spreads to association cortices, and other neuropsychological deficits can be detected. A comprehensive neuropsychological examination encompassing several cognitive domains can provide a pattern of altered and preserved functions that is helpful to early detection, differential diagnosis and even prognosis of progression in predementia stages. The use of adapted and standardized instruments is necessary to properly estimate cognitive and functional performance in AD.

Acoustic markers associated with impairment in language processing in Alzheimer's Disease

This study broaches in a novel way the analysis of cognitive impairment characteristic of the early stages of Alzheimer's Disease (AD). Specifically, we attempt to determine the acoustic speech parameters that are sensitive to the onset of the disease, and their association with the language deficit characteristic of AD. Speech analysis was carried out on 21 elderly patients with AD using Praat software, which analyzes the acoustic components of speech. The data obtained were subjected to stepwise regression, using the overall scores obtained in the test as the criterion variable, and the scores on the frequency, amplitude and periodicity variables as predictors of performance. We found that the percentage of voiceless segments explains a significant portion of the variance in the overall scores obtained in the neuropsychological test. This component seems to be related mainly to the patient's ability in phonological fluency. This finding could permit the creation of a diagnostic test for AD through analysis of the acoustic speech parameters at very low cost in terms of both time and resources.

Subtle cognitive impairment in elders with Mini-Mental State Examination scores within the 'normal' range

OBJECTIVE

The Mini-Mental State Examination (MMSE) is commonly used as a screening test for dementia, yet MMSE scores above the cut-off for dementia (24-30) are widely thought to have limited utility, particularly in older persons. The study investigates whether scores within this range can be indicative of pre-symptomatic levels of cognitive impairment.

METHODS

Ninety-six community-dwelling older persons aged 62-89  years (mean = 75.2 years), who had obtained MMSE scores between 25 and 30, were tested on the computer-based Subtle Cognitive Impairment Test (SCIT).

RESULTS

Compared with individuals who obtained a perfect score of 30 on the MMSE, individuals with scores of 28-29 made more errors on the SCIT, whereas those with scores of 25-27 on the MMSE made the most errors on the SCIT (F(2,94) = 9.84, p < 0.01). Individuals who made errors in the language (r(94) = -0.47, p < 0.01), attention (r(94) = 0.24, p < 0.05) and visual construction (r(94) = -0.27, p < 0.01) subtests of the MMSE were more likely to display impaired SCIT performance.

CONCLUSIONS

The pattern of performance on the SCIT varied in a systematic way, depending on the MMSE subtest in which the errors were made, raising the possibility that there may be different subtypes of subtle cognitive impairment within the ostensibly normal population of older persons.

Agraphia in Korean patients with early onset Alzheimer's disease

BACKGROUND

Agraphia in Korean patients may be different from agraphia in other patients who use alphabetical writing systems due to the "visuoconstructional script" characteristics of the Korean writing system, Hangul. Patients with early onset Alzheimer's disease (EOAD) have a severe degree of hypometabolism in the parietal area, which is known to be involved in processing visuospatial function. Thus, we explored the diverse error patterns manifested in writing single syllables in Korean patients with EOAD.

METHODS

A study sample of 35 patients with EOAD and 18 healthy controls (HC) performed a Hangul writing task. We analyzed the erroneous responses of the subjects according to visuoconstructional and linguistic characteristics. In addition, we evaluated the relationship between Hangul writing and the neuropsychological variables as well as the severity of dementia.

RESULTS

When comparing the total number of erroneous responses between EOAD and HC groups, the performances of EOAD patients were significantly worse than those of HC. EOAD patients demonstrated visuoconstructional errors even in the early stages of the disease. Severity of dementia and multiple cognitive domains such as attention, language, immediate memory, and frontal executive functions significantly correlated with the performance of Hangul writing.

CONCLUSION

Our findings suggest that patients with EOAD exhibit not only linguistic errors but also visuoconstructional manifestations of agraphia, which are associated with cognitive impairments in the multiple domains.

Linguistic development in Alzheimer's disease: 12 months language training including use of a personal computer system: a pilot study

OBJECTIVE

To assess linguistic development in patients with mild and moderate Alzheimer's disease (AD) who underwent treatment with a drug and regularly performed language activities.

METHODS

For 12 months, five patients with mild-to-moderate AD participated in a Stimulation-Activation-Training programme (SAT) including pragmatic, semantic, writing, conversation and counting sessions. A computer with exercise programs and a keyboard with a printer were used as complements to ordinary stationery. The linguistic competence was assessed using a standardized assessment tool.

RESULTS

The assessment indicated preservation or slight changes of the patients' linguistic competence over the period and greater confidence in the management of the language. The personal computer system was a well accepted novelty.

CONCLUSION

The documented approach, SAT training interlaced with everyday life tasks, may be helpful in maintaining and improving remaining language functions in patients with mild or moderate AD.

The expression and assessment of emotions and internal states in individuals with severe or profound intellectual disabilities

The expression of emotions and internal states by individuals with severe or profound intellectual disabilities is a comparatively under-researched area. Comprehensive or standardized methods of assessing or understanding the emotions and internal states within this population, whose ability to communicate is significantly compromised, do not exist. The literature base will be discussed and compared to that applicable to the general population. Methods of assessing broader internal states, notably depression, anxiety, and pain within severe or profound intellectual disabilities are also addressed. Finally, this review will examine methods of assessing internal states within genetic syndromes, including hunger, social anxiety, and happiness within Prader-Willi, Fragile-X and Angelman syndrome. This will allow for identification of robust methodologies used in assessing the expression of these internal states, some of which may be useful when considering how to assess emotions within individuals with intellectual disabilities.

Neuroanatomical structures and segregated circuits

Segregated neural circuits that effect particular domain-specific behaviors can be differentiated from neuroanatomical structures implicated in many different aspects of behavior. The basal ganglionic components of circuits regulating nonlinguistic motor behavior, speech, and syntax all function in a similar manner. Hence, it is unlikely that special properties and evolutionary mechanisms are associated with the neural bases of human language.

How to grow a human

I enlarge on the theme that the brain mechanisms required for languageand other aspects of the human mind evolved through selective changes in the regulatory genes governing growth. Extension of the period of postnatal growth increases the role of the environment in structuring the brain, and spatiotemporal programming (heterochrony) ofgrowth might explain hierarchical representation, hemispheric specialization, and perhaps sex differences.

Genes, specificity, and the lexical/functional distinction in language acquisition

Contrary to Müller's claims, and in support of modular theories, genetic factors play a substantial and significant role in language. The finding that some children with specific language impairment (SLI) have nonlinguistic impairments may reflect improper diagnosis of SLI or impairments that are secondary to linguistic impairments. Thus, such findings do not argue against the modularity thesis. The lexical/functional distinction appears to be innate and specifically linguistic and could be instantiated in either symbolic or connectionist systems.

Autonomy of syntactic processing and the role of Broca's area

Both autonomy and local specificity are compatible with observed interconnectivity at the cell level when considering two different levels: cell assemblies and brain systems. Early syntactic structuring processes in particular are likely to representan autonomous module in the language/brain system.

Neurobiological approaches to language: Falsehoods and fallacies

The conclusion that language is not really innate or modular is based on several fallacies. I show that the target article confuses communicative skills with linguistic abilities, and that its discussion of brain/language relations is replete with factual errors. I also criticize its attempt to contrast biological and linguistic principles. Finally, I argue that no case is made for the “alternative” approach proposed here.

Is human language just another neurobiological specialization?

One can disagree with Müller that it is neurobiologically questionable to suppose that human language is innate, specialized, and species-specific, yet agree that the precise brain mechanisms controlling language in any individual will be influenced by epigenesis and genetic variability, and that the interplay between inherited and acquired aspects of linguistic capacity deserves to be investigated.

Evolutionary principles and the emergence of syntax

The belief that syntax is an innate, autonomous, species-specific module is highly questionable. Syntax demonstrates the mosaic nature of evolutionary change, in that it made use of (and led to the enhancement of) numerous preexisting neurocognitive features. It is best understood as an emergent characteristic of the explosion of semantic complexity that occurred during hominid evolution.

Neurobiology and linguistics are not yet unifiable

Neurobiological models of language need a level of analysis that can account for the typical range of language phenomena. Because linguistically motivated models have been successful in explaining numerous language properties, it is premature to dismiss them as biologically irrelevant. Models attempting to unify neurobiology and linguistics need to be sensitive to both sources of evidence.

An innate language faculty needs neither modularity nor localization

Müller misconstrues autonomy to mean strict locality of brain function, something quite different from the functional autonomy that linguists claim. Similarly, he misperceives the interaction of learned and innate components hypothesized in current generative models. Evidence from sign languages, Creole languages, and neurological studies of rare forms of aphasia also argues against his conclusions.

Sign language and the brain: Apes, apraxia, and aphasia

The study of signed languages has inspired scientific' speculation regarding foundations of human language. Relationships between the acquisition of sign language in apes and man are discounted on logical grounds. Evidence from the differential hreakdown of sign language and manual pantomime places limits on the degree of overlap between language and nonlanguage motor systems. Evidence from functional magnetic resonance imaging reveals neural areas of convergence and divergence underlying signed and spoken languages.

Innateness, autonomy, universality? Neurobiological approaches to language

The concepts of the innateness, universality, species-specificity, and autonomy of the human language capacity have had an extreme impact on the psycholinguistic debate for over thirty years. These concepts are evaluated from several neurobiological perspectives, with an emphasis on the emergence of language and its decay due to brain lesion and progressive brain disease.

Evidence of perceptuomotor homologies and preadaptations for human language in nonhuman primates suggests a gradual emergence of language during hominid evolution. Regarding ontogeny, the innate component of language capacity is likely to be polygenic and shared with other developmental domains. Dissociations between verbal and nonverbal development are probably rooted in the perceptuomotor specializations of neural substrates rather than the autonomy of a grammar module. Aphasiologicaldata often assumed to suggest modular linguistic subsystems can be accounted for in terms of a neurofunctional model incorporating perceptuomotor-based regional specializationsand distributivity of representations. Thus, dissociations between grammatical functors and content words are due to different conditions of acquisition and resulting differences in neural representation. Human brains are characterized by multifactorial interindividual variability, and strict universality of functional organization is biologically unrealistic.

A theoretical alternative is proposed according to which (1) linguistic specialization of brain areas is due to epigenetic and probabilistic maturational events, not to genetic ”hard-wiring,” and (2) linguistic knowledge is neurally represented in distributed cell assemblies whose topography reflects the perceptuomotor modalities involved in the acquisition and use of a given item of knowledge.

Diagnostic utility of sound naming in early Alzheimer's disease

While it is well known that picture naming (PN) is impaired in Alzheimer's disease (AD), sound naming (SN) has not been thoroughly investigated. We postulated that SN might be impaired more severely and earlier than PN, given the early involvement of the temporal cortex by AD-related pathology. SN and PN were assessed in 21 normal participants, 40 patients with mild cognitive impairment (MCI), and 27 patients in early stages of AD. Our results showed that SN accuracy and latency were more sensitive to advancing pathology in AD than PN accuracy and latency. SN was more useful and specific in distinguishing MCI patients from normal participants and therefore in potentially identifying the subset of MCI patients who already have impairment in more than one cognitive domain and may actually have incipient AD. These findings indicate a potential diagnostic utility of SN for early detection of the disease. Furthermore, even though most AD patients demonstrated more or less comparable impairment in both tasks, some were disproportionately impaired on SN and others were differentially impaired on PN. Future studies may be able to show that these discrepant groups correspond to patients with right and left hemisphere predominant AD, respectively.

The Toll-->NFkappaB signaling pathway mediates the neuropathological effects of the human Alzheimer's Abeta42 polypeptide in Drosophila

Alzheimer's (AD) is a progressive neurodegenerative disease that afflicts a significant fraction of older individuals. Although a proteolytic product of the Amyloid precursor protein, the Alphabeta42 polypeptide, has been directly implicated in the disease, the genes and biological pathways that are deployed during the process of Alphabeta42 induced neurodegeneration are not well understood and remain controversial. To identify genes and pathways that mediated Alphabeta42 induced neurodegeneration we took advantage of a Drosophila model for AD disease in which ectopically expressed human Alphabeta42 polypeptide induces cell death and tissue degeneration in the compound eye. One of the genes identified in our genetic screen is Toll (Tl). It encodes the receptor for the highly conserved Tl-->NFkB innate immunity/inflammatory pathway and is a fly homolog of the mammalian Interleukin-1 (Ilk-1) receptor. We found that Tl loss-of-function mutations dominantly suppress the neuropathological effects of the Alphabeta42 polypeptide while gain-of-function mutations that increase receptor activity dominantly enhance them. Furthermore, we present evidence demonstrating that Tl and key downstream components of the innate immunity/inflammatory pathway play a central role in mediating the neuropathological activities of Alphabeta42. We show that the deleterious effects of Alphabeta42 can be suppressed by genetic manipulations of the Tl-->NFkB pathway that downregulate signal transduction. Conversely, manipulations that upregulate signal transduction exacerbate the deleterious effects of Abeta42. Since postmortem studies have shown that the Ilk-1-->NFkB innate immunity pathway is substantially upregulated in the brains of AD patients, the demonstration that the Tl-->NFkB signaling actively promotes the process of Alphabeta42 induced cell death and tissue degeneration in flies points to possible therapeutic targets and strategies.

Analysis of brief language tests in the detection of cognitive decline and dementia

Lexical access difficulties are frequent in normal aging and initial stages of dementia.Verbal fluency tests are valuable to detect cognitive decline, evidencing lexico-semantic and executive dysfunction.

Raf kinase inhibitory protein knockout mice: expression in the brain and olfaction deficit

Raf kinase inhibitory protein (RKIP-1) is involved in the regulation of the MAP kinase, NF-kappaB, and GPCR signaling pathways. It is expressed in numerous tissues and cell types and orthologues have been documented throughout the animal and plant kingdoms. RKIP-1 has also been reported as an inhibitor of serine proteases, and a precursor of a neurostimulatory peptide. RKIP-1 has been implicated as a suppressor of metastases in several human cancers. We generated a knockout strain of mice to further assess RKIP-1's function in mammals. RKIP-1 is expressed in many tissues with the highest protein levels detectable in testes and brain. In the brain, expression was ubiquitous in limbic formations, and homozygous mice developed olfaction deficits in the first year of life. We postulate that RKIP-1 may be a modulator of behavioral responses.

Apolipoprotein epsilon-4 allele and the two-year progression of cognitive function in Chinese subjects with late-onset Alzheimer's disease

BACKGROUND

Although the significance of apolipoprotein E4 (Apo E4) in Alzheimer's disease (AD) has been well established in Caucasian populations, its role in determining the rate of cognitive decline in other ethnic groups has yet to be determined. This study examined the two-year progression of cognitive decline and its association with Apo E4 allelic status in a group of Chinese elderly subjects with AD.

METHOD

One hundred and four Chinese subjects with mild and moderate AD as assessed by the Clinical Dementia Rating (CDR 1 and 2) were followed up at a mean (SD) duration of 22.53 (5.21) months. The rate of cognitive decline and its association with Apo E4 allelic status was evaluated

RESULTS

At follow-up, 74 (73 percent) subjects were reassessed. Forty-nine remained stable at the same CDR and 25 had deteriorated. The mean (SD) deterioration in the Mini-Mental State Examination (MMSE) was 2.52 (4.38) and in the Mattis Dementia Rating Scale (DRS) was 9.03 (14.98) (paired t-test, p < 0. 001). There was no significant difference in the baseline MMSE and DRS scores between the "stable", "deteriorated", or "deceased" groups. Mildly demented subjects with the Apo E4 allele were more likely to have deteriorated to a more severe CDR than subjects without the Apo E4 allele (Pearson chi2 = 5.72, df 1, p = 0.017, Odds ratio = 6.3, CI 1.3 to 30.53).

CONCLUSION

The presence of the Apo E4 allele may influence the rate of cognitive deterioration, particularly in subjects with mild AD.

Transgenic models of Alzheimer's disease: learning from animals

As the scope of the problem of Alzheimer's disease (AD) grows due to an aging population, research into the devastating condition has taken on added urgency. Rare inherited forms of AD provide insight into the molecular pathways leading to degeneration and have made possible the development of transgenic animal models. Several of these models are based on the overexpression of amyloid precursor protein (APP), presenilins, or tau to cause production and accumulation of amyloid-beta into plaques or hyperphosphorylated tau into neurofibrillary tangles. Producing these characteristic neuropathological lesions in animals causes progressive neurodegeneration and in some cases similar behavioral disruptions to those seen in AD patients. Knockout models of proteins involved in AD have also been generated to explore the native functions of these genes and examine whether pathogenesis is due to loss of function or toxic gain of function in these systems. Although none of the transgenic lines models the human condition exactly, the ability to study similar pathological processes in living animals have provided numerous insights into disease mechanisms and opportunities to test therapeutic agents. This chapter reviews animal models of AD and their contributions to developing therapeutic approaches for AD.

Confrontation naming does not add incremental diagnostic utility in MCI and Alzheimer's disease

As the incidence of dementia increases, there is a growing need to determine the diagnostic utility of specific neuropsychological tests in the early diagnosis of Alzheimer's disease (AD). In this study, the relative utility of Boston Naming Test (BNT) in the diagnosis of AD was examined and compared to the diagnostic utility of other neuropsychological measures commonly used in the evaluation of AD. Individuals with AD (n = 306), Mild Cognitive Impairment (MCI; n = 67), and cognitively normal subjects (n = 409) with at least 2 annual evaluations were included. Logistic regression analysis suggested that initial BNT impairment is associated with increased risk of subsequent AD diagnosis. However, this risk is significantly less than that imparted by measures of delayed recall impairments. A multivariate Cox proportional hazards regression analysis suggested that BNT impairment imparted no additional risk for subsequent AD diagnosis after delayed recall impairments were included in the model. Although BNT impairment occurred in all severity groups, it was ubiquitous only in moderate to severe dementia. Collectively these results suggest that although BNT impairments become more common as AD progresses, they are neither necessary for the diagnosis of AD nor particularly useful in identifying early AD.

The evolution of dysgraphia in Alzheimer’s disease

Evidence from recent studies suggests that writing may be an aspect of cognition capable of identifying impairments specific to patients with Alzheimer's Disease (AD). The precise nature and progression of the writing disorder, however, remains unclear. The current study assessed the central and peripheral aspects of writing among a sample of minimal, mild and moderate AD patients and a group of healthy elderly controls on a narrative description task. Comparisons of the two groups indicated that AD patients suffer from a primary impairment at the semantic level. Even those in the minimal stages of the disease could be differentiated from controls on measures of word finding and information conveyed. This semantic impairment was coupled with a secondary milder impairment in phonological processing. The prevalence of phonological errors increased, but no shift in error type (plausible/implausible) was identified as the disease progressed. In addition to the central impairments, patients evinced damage at the peripheral level. In the more severe stages, patients experienced more problems with letter formation and stroke placement and tended to rely upon the more simplistic writing form of print. The writing impairment in AD is multi-componential in nature and follows the pattern of cortical deterioration reported in the brains of AD patients.

Essentials of the proper diagnoses of mild cognitive impairment, dementia, and major subtypes of dementia

Loss of cognitive function in the elderly population is a common condition encountered in general medical practice. Diagnostic criteria and approaches have become more refined and explicit in the past several years. Precise diagnosis is feasible clinically. In this article, the precursor state and major subtypes of dementia are considered. Mild cognitive impairment is the term given to patients with cognitive impairment that is detectable by clinical criteria but does not produce impairment in daily functioning. When daily functioning is impaired as a result of cognitive decline, dementia is the appropriate syndromic label. Specific causes of dementia tend to have distinctive clinical presentations: the anterograde amnesic syndrome of Alzheimer disease; the syndrome of dementia with cerebrovascular disease; the syndrome of Lewy body dementia with its distinctive constellation of extrapyramidal features, disordered arousal, and dementia; the behavioral-cognitive syndrome of frontotemporal dementia; the primary progressive aphasias; and the rapidly progressive dementias. Because dementia syndromes have distinctive natural histories, precise diagnosis leads to a better understanding of prognosis. As new treatments become available for Alzheimer disease, the most common of the dementias, accurate diagnosis allows the appropriate patients to receive treatment.