Linguistics Dementia and Language
by
Joël Macoir
  • LAST MODIFIED: 21 April 2021
  • DOI: 10.1093/obo/9780199772810-0275

Introduction

Neurodegenerative diseases progress over three distinct stages: (1) the preclinical stage, at which individuals can be placed on a continuum ranging from completely asymptomatic to a very subtle decline; (2) mild cognitive impairment (MCI), which is the symptomatic predementia stage of dementia, characterized by impairment in memory or other domains of cognition; and (3) dementia itself. Dementia is a common condition that mainly occurs in older people. It is characterized by a significant decline of cognitive functioning severe enough to impact activities of daily living and social functioning. The loss of cognitive functioning in dementia may affect long-term and short-term memory, attention, visual perception, executive functions, motor planning and execution, problem-solving, and language. Dementia can be caused by a wide range of pathological entities, among which Alzheimer’s disease (AD) is the most common. Other dementia types include vascular dementia (VaD), dementia in atypical parkinsonian syndromes such as dementia with Lewy bodies (DLB) and corticobasal degeneration (CBD), and frontotemporal dementia (FTD). While these are commonly associated with an impairment of episodic memory, the major forms of dementia are also characterized by deficits of language affecting comprehension and production abilities of words and sentences. Clinical linguistic profiles usually associated with common forms of dementia have been described, some more detailed than others. Neurolinguistic studies also went further than the mere description of symptoms and identified the functional localization of impaired and preserved processing components of the linguistic processing system in dementias. The initial evaluation is the first significant step toward the clinical management of dementia and is based on consensual diagnostic criteria. In some dementia syndromes, such as primary progressive aphasia (PPA), the characterization of language deficits is of major importance for the differential diagnosis of dementia. This article focuses on bibliographic resources related to language and communication disorders in mild cognitive disorders as well as in the most frequent primary progressive syndromes of dementia.

General Overviews

Deficits of spoken and written language processes are accompanying symptoms of the major forms of primary progressive dementias as well as vascular cognitive diseases. These deficits are often prominent symptoms of the disease and may occur early in the process. Substantial information is available for spoken language disturbances in AD as well as in PPA. However, relatively little is known about the patterns of spoken language deterioration in VaD and in dementia associated with atypical parkinsonian syndromes. Finally, knowledge about written language deficits in the major forms of dementia and their contribution to the overall language syndrome are much less established in the literature. The overviews listed here are suitable for graduate students, clinicians, and early-stage researchers. Ames, et al. 2017; Miller and Boeve 2016; and Smith and Farias 2018 are three books recommended for a general overview of the various aspects of neurodegenerative diseases, including diagnosis, epidemiology, neurobiology, treatment, and the characteristics of cognitive impairments. Reilly, et al. 2010 addresses the clinical and neuropsychological signs of non-Alzheimer’s dementias, while Grossman 2008; Macoir, et al. 2015; and Reilly, et al. 2011 encompass most aspects of language impairment in MCI and the major forms of dementia. In most of the following sections, the articles presenting the diagnostic criteria of the different neurodegenerative diseases are referenced, in order to provide the reader with a general overview of their clinical aspects.

  • Ames, D., J. T. O’Brien, and A. Burns. 2017. Dementia. 5th ed. Boca Raton, FL: CRC Press.

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    This book is intended for clinicians working in the field of dementia. In Part 1, they will find an extensive description of all the important issues of dementia, including health economic aspects, driving and palliative care. The other 6 parts concern the clinical aspects of the major forms of dementia (MCI, AD, VaD, DLB, FTD).

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  • Grossman, M. 2008. Language in dementia. In Handbook of the neuroscience of language. Edited by B. Stemmer and H. A. Whitaker, 279–287. Amsterdam: Elsevier.

    DOI: 10.1016/B978-008045352-1.00027-6Save Citation »Export Citation » Share Citation »

    This informative text addresses the impairment of the following specific aspects of language in dementia: phonology and speech processing, lexical retrieval in word production, semantic memory, and grammatical processing.

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  • Macoir, J., Y. Turgeon, and R. Laforce Jr. 2015. Language processes in delirium and dementia. In International encyclopedia of the social and behavioral sciences. 2d ed. Vol. 13. Edited by James D. Wright, 360–367. Oxford: Elsevier.

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    In this chapter, the authors provide a comprehensive review of language and communication disorders in AD, VaD, LBD, and PPA. In some of them, language deficits result from impairment to linguistic processes per se. In others, they rather result from impairments affecting other cognitive functions.

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  • Miller, B. L., and B. F. Boeve. 2016. The behavioral neurology of dementia. 2d ed. Cambridge: Cambridge Univ. Press.

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    This book provides students, clinicians, and researchers with in-depth knowledge of all the clinical aspects of the major forms of dementia, illustrated by clinical descriptions of diseases and symptoms.

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  • Reilly, J., A. D. Rodriguez, M. Lamy, and J. Neils-Strunjas. 2010. Cognition, language, and clinical pathological features of non-Alzheimer’s dementias: An overview. Journal of Communication Disorders 43.5: 438–452.

    DOI: 10.1016/j.jcomdis.2010.04.011Save Citation »Export Citation » Share Citation »

    This review article provides an overview of cognition and language characteristics of the most common non-Alzheimer’s dementias, namely PPA, VaD, LBD, and Parkinson’s disease. Their specific pathological features are also briefly outlined.

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  • Reilly, J., J. Troche, and M. Grossman. 2011. Language processing in dementia. In The handbook of Alzheimer’s disease and other dementias. Edited by A. E. Budson and N. W. Kowall, 336–368. Hoboken, NJ: Wiley-Blackwell.

    DOI: 10.1002/9781444344110.ch12Save Citation »Export Citation » Share Citation »

    This overview provides distinctive descriptions of disorders affecting phonology, naming, as well as semantic, grammatical, and discourse processing in AD and in PPA.

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  • Smith, G. E., and S. T. Farias, eds. 2018. APA handbook of dementia. APA Handbooks in Psychology. Washington, DC: American Psychological Association.

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    This comprehensive handbook addresses assessment, comorbidity, evaluation, and treatment of MCI, AD, LBD, VaD, FTD, and other less common dementias. It is a valuable resource for health professionals, researchers, and students interested in neurodegenerative disease.

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Language Impairment in Mild Cognitive Impairment (MCI) and Alzheimer’s Disease (AD)

MCI is the symptomatic prodromal stage of major neurocognitive disorders, including those with AD. MCI is a heterogeneous condition in which individuals may experience gradual cognitive decline as well as changes in personality and behavior. Two subtypes of MCI are acknowledged as distinct clinical syndromes, according to the involvement of memory functions: amnestic and non-amnestic. Readers will find a comprehensive description, along with the diagnostic criteria of MCI, in the review article Petersen 2016. With respect to language impairment, Johnson and Lin 2014 and Taler and Philipps 2008 are the most complete reviews of language impairment in MCI. There also exist numerous studies focusing on specific domains or linguistic abilities in MCI, such as verbal fluency, semantic processing, and discourse production. The AD stage is characterized by significant cognitive impairment and loss or significant decline in performance of instrumental activities of daily living, according to Scheltens, et al. 2016. The diagnostic criteria for AD are presented in McKhann, et al. 2011. Minati, et al. 2009 is also a good source of information regarding the clinical aspects of AD. As for language, Taler and Philipps 2008; Szatloczki, et al. 2015; and Verma and Howard 2012 provide a general overview of the linguistic domains and abilities usually affected in AD. For those wishing to explore in more detail, there exists a vast literature on the specific domains (e.g., lexical access, morphology, syntax, discourse) that may be affected in AD.

  • Johnson, M., F. Lin. 2014. Communication difficulty and relevant interventions in mild cognitive impairment: Implications for neuroplasticity. Topics in Geriatric Rehabilitation 30.1: 18–34.

    DOI: 10.1097/TGR.0000000000000001Save Citation »Export Citation » Share Citation »

    This systematic review of the literature focuses on language impairment affecting expressive and receptive communication in individuals with MCI. Of the twenty-eight observational studies reviewed, the authors showed that all aspects of communication are generally impaired in MCI, compared to healthy individuals.

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  • McKhann, G. M., D. S. Knopman, H. Chertkow, et al. 2011. The diagnosis of dementia due to Alzheimer’s disease: Recommendations from the National Institute on Aging-Alzheimer’s Association workgroups on diagnostic guidelines for Alzheimer’s disease. Alzheimer’s & Dementia 7.3: 263–269.

    DOI: 10.1016/j.jalz.2011.03.005Save Citation »Export Citation » Share Citation »

    This article, which emerged from the work of an international panel of clinicians and scientists, presents the criteria for all-cause dementia and for probable and possible dementia due to AD. These criteria involve elements related to the progression of the disease, the nature of cognitive deficits, and the presence or absence of concomitant diseases or symptoms.

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  • Minati, L., T. Edginton, M. G. Bruzzone, and G. Giaccone. 2009. Current concepts in Alzheimer’s disease: A multidisciplinary review. American Journal of Alzheimer’s Disease and Other Dementias 24.2: 95–121.

    DOI: 10.1177/1533317508328602Save Citation »Export Citation » Share Citation »

    This article is a survey of general knowledge on epidemiology, genetics, risk factors, progression of cognitive deficits (memory, language, visual processing, attention, executive functions, praxis), assessment methods, and treatment of AD.

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  • Petersen, R. C. 2016. Mild cognitive impairment. Continuum 22.2: 404–418.

    DOI: 10.1212/CON.0000000000000313Save Citation »Export Citation » Share Citation »

    At the MCI stage of AD, individuals show low performance in one or more cognitive domains, including language, while they usually maintain their independence of function in daily life. In this article, the author provides a comprehensive portrait of MCI, including diagnostic criteria and clinical presentation, illustrated by two cases.

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  • Scheltens, P., K. Blennow, M. M. B. Breteler, et al. 2016. Alzheimer’s disease. Lancet 388.10043: 505–517.

    DOI: 10.1016/S0140-6736(15)01124-1Save Citation »Export Citation » Share Citation »

    This review article, which is directed more to experts, covers all the various aspects of dementia due to AD; that is, clinical signs and symptoms, epidemiology, imaging, treatment, etc.

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  • Szatloczki, G., I. Hoffmann, V. Vincze, J. Kalman, and M. Pakaski. 2015. Speaking in Alzheimer’s disease, is that an early sign? Importance of changes in language abilities in Alzheimer’s disease. Frontiers in Aging Neuroscience 7:195.

    DOI: 10.3389/fnagi.2015.00195Save Citation »Export Citation » Share Citation »

    In this article, the authors examine the relation between AD, language functions, and language domains. More specifically, they address the impairment of phonetics and phonology as well as lexical, semantic, and pragmatic domains of language in AD. They also briefly explore the relationship between language and cognition in AD.

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  • Taler, V., and N. Philipps. 2008. Language performance in Alzheimer’s disease and mild cognitive impairment: A comparative review. Journal of Clinical and Experimental Neuropsychology 30.5: 501–556.

    DOI: 10.1080/13803390701550128Save Citation »Export Citation » Share Citation »

    In this review, the authors describe the performance of individuals with MCI in tasks assessing semantic and syntactic processing, writing, and word, sentence, and discourse production and comprehension. Then they compare these findings to the linguistic impairment usually observed in AD. Finally, they provide recommendations for the optimal assessment of language in MCI.

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  • Verma, M., and R. J. Howard. 2012. Semantic memory and language dysfunction in early Alzheimer’s disease: A review. International Journal of Geriatric Psychiatry 27.12: 1209–1217.

    DOI: 10.1002/gps.3766Save Citation »Export Citation » Share Citation »

    This paper focused on the impairment of language functions occurring early in the course of AD. The authors show that, at this early stage, language is mainly characterized by semantic impairment affecting naming abilities and verbal fluency.

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Language Impairment in Vascular Dementia (VaD)

Cognitive impairment due to vascular disease may result from an array of causes, including dementias following ischemic or hemorrhagic stroke, repeated cerebral infarction, and chronic ischemia without discrete infarction. Vascular cognitive impairment may range from the least severe (i.e., vascular mild cognitive impairment) to the most severe (i.e., vascular dementia, or VaD). Readers will find a comprehensive description, along with the diagnostic criteria of VaD in the review article Gorelick, et al. 2011. The review article O’Brien and Thomas 2015 also presents a comprehensive portrait of the clinical and pathological characteristics of VaD. Compared to AD, there is much more heterogeneity of cognitive impairment in VaD. Therefore, in contrast with AD, less is known about the patterns of cognitive deterioration in VaD. In VaD, these deficits are directly dependent on the brain areas affected by the vascular pathology. The most commonly reported cognitive impairments in VaD are bradyphrenia (slowed cognition), dysexecutive symptoms (e.g., difficulty in problem-solving and planning), and decreased initiation and spontaneity. Few studies have systematically described cognitive and language disorders in VaD, given their substantial heterogeneity. Most of them aimed to differentiate VaD from AD. In this respect, Levy and Chelune 2007 and Desmond 2004 present a succinct contrast between AD and VaD in regard to cognitive and linguistic impairment. Overall, these studies indicate that the language impairment in VaD mainly results from primary executive dysfunction.

Language Impairment in Primary Progressive Aphasia (PPA)

Primary progressive aphasia (PPA) is a neurodegenerative syndrome associated with atrophy of the frontal and temporal regions of the left hemisphere, typically resulting in language impairment. PPA is a heterogeneous condition, in which the most prominent clinical feature is a difficulty with language (deficit of language production, object naming, syntax, or word comprehension), while other cognitive domains are not affected at onset and in the early stages of the disease (Mesulam, et al. 2014). Recommendations for the diagnosis and the classification of PPA were proposed by an international group of experts (Gorno-Tempini, et al. 2011). These recommendations provide a classification of PPA and its three main variants, namely the nonfluent/agrammatic variant (nfvPPA), semantic variant (svPPA), and logopenic variant (lvPPA). Each of these variants will be separately described in further subsections. Readers will find a comprehensive description of language impairment in the three PPA variants, along with their clinical presentation, assessment framework, and neuroanatomical substrates, in Marshall, et al. 2018. An overview of the clinical, anatomical and pathological features of the three PPA variants is also provided in Montembeault, et al. 2018, as well as in Rohrer and Warren 2019. Finally, the linguistic characteristics of the three PPA variants are specifically addressed in Grossman 2018.

Language Impairment in the Nonfluent/Agrammatic Variant PPA (nfvPPA)

According to the classification proposed by Gorno-Tempini, et al. 2011 (cited under Language Impairment in Primary Progressive Aphasia (PPA)), at least one of the following two core features must be present to detect nfvPPA: (1) effortful, halting speech with inconsistent speech sound errors and distortions (apraxia of speech); and (2) agrammatism in language production. Moreover, at least two of the following three additional features must be present: (1) impaired comprehension of syntactically complex sentences, (2) spared single-word comprehension, and (3) spared object knowledge. Readers will find a comprehensive description of the syndrome in Grossman 2012 as well as in Schaffer and Henry 2020. As regards the first core feature of nfvPPA, individuals may present apraxia of speech, characterized by deficits in motor planning and sequencing of speech movements. As suggested by Duffy, et al. 2014, these deficits are responsible for the production of phonological errors as well as the slow rate and abnormal pauses in connected speech. The second clinical hallmark of nfvPPA is agrammatism in speech production, as observed in connected speech by Boschi, et al. 2017. As shown by Thompson and Mack 2014, agrammatism may also manifest in sentence comprehension, with difficulty in processing syntactically complex sentences, as well as in processing grammatical morphology, functional categories, and verb argument structure. By contrast, Grossman 2012 shows that single-word comprehension and semantic processing are usually unaffected in nfvPPA.

Language Impairment in the Semantic Variant PPA (svPPA)

The svPPA is a clinical syndrome resulting from atrophy of the temporal lobes, leading to the selective impairment of semantic memory. Before the classification proposed by Gorno-Tempini, et al. 2011 (cited under Language Impairment in Primary Progressive Aphasia (PPA)), this syndrome was formerly known as semantic dementia. According to this classification, the following two core features must be present to establish a diagnosis of svPPA: (1) impaired confrontation naming, and (2) impaired single-word comprehension. Moreover, at least three of the following additional features must be present: (1) impaired object knowledge, (2) surface dyslexia or dysgraphia, (3) spared repetition, and (4) spared speech production (grammar and motor speech). A detailed description of the svPPA syndrome is provided in Hodges and Patterson 2007. The book chapter Hodges, et al. 2016 also presents an overview of the svPPA. The impact of semantic impairment on word and object processing is specifically addressed in Reilly and Peelle 2008.

  • Chiou, H. S., and A. H. Allison. 2020. Semantic dementia. In Primary progressive aphasia and other frontotemporal dementias. Edited by R. L. Utianski, 45–76. San Diego, CA: Plural Publishing, Inc.

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    This concise chapter is relevant for nonresearchers and clinicians who want to have an overview, based on evidence-based practice and research findings, of the clinical presentation, language, and cognitive manifestations of the svPPA.

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  • Hodges, J. R., and K. Patterson. 2007. Semantic dementia: A unique clinicopathological syndrome. Lancet Neurology 6.11: 1004–1014.

    DOI: 10.1016/S1474-4422(07)70266-1Save Citation »Export Citation » Share Citation »

    In this article, Hodges and Patterson describe the epidemiological, cognitive, and radiological features of the svPPA. The clinical features and the neuropsychological findings are explicitly described. The authors also interpret the nature of the impairment observed in svPPA in light of the theoretical models of semantic memory.

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  • Hodges, J. R., S. Savage, and K. E. Patterson. 2016. Semantic dementia (semantic variant primary progressive aphasia). In The Behavioral neurology of dementia. Edited by B. L. Miller and B. F. Boeve, 178–193. Cambridge, UK: Cambridge Univ. Press.

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    The clinical, neuropsychological, and radiological findings in svPPA are summarized in this book chapter. The impact of semantic impairment on verbal (naming, word comprehension) and nonverbal (object recognition, object use) knowledge and processing is more particularly addressed.

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  • Reilly J., and J. E. Peelle. 2008. Effects of semantic impairment on language processing in semantic dementia. Seminars in Speech and Language 29.1: 32–43.

    DOI: 10.1055/s-2008-1061623Save Citation »Export Citation » Share Citation »

    In addition to the description of the svPPA syndrome, this review article discusses the effects of semantic impairment on language processing within the context of theoretical models of semantic memory. The authors also address the nature of the deficits observed in word naming and discourse production in this syndrome.

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Language Impairment in the Logopenic Variant PPA (lvPPA)

The lvPPA is the most recently identified PPA variant. According to the clinical criteria established in 2011, the two core features essential to the diagnosis of lvPPA are the presence of anomia in spontaneous speech and confrontation naming, and impaired repetition of sentences and phrases (Gorno-Tempini, et al. 2011, cited under Language Impairment in Primary Progressive Aphasia (PPA)). At least three of the following additional features must be present: (1) production of phonological errors, (2) preservation of semantic memory, (3) preservation of articulation and prosody, and (4) absence of agrammatism. Detailed descriptions of the lvPPA syndrome are provided in Henry and Gorno-Tempini 2010, Pressman and Gorno-Tempini 2016, and Rising and Beeson 2020. In all these bibliographic sources, background knowledge on the clinical presentation of lvPPA, underlying cognitive impairment, and differential diagnosis are presented.

  • Henry, M. L., and M. L. Gorno-Tempini. 2010. The logopenic variant of primary progressive aphasia. Current Opinion in Neurology 23.6: 633–637.

    DOI: 10.1097/WCO.0b013e32833fb93eSave Citation »Export Citation » Share Citation »

    This review outlines the speech-language profile and the associated cognitive and behavioral characteristics of the lvPPA. The authors also address the underlying deficit of the syndrome; that is, the impairment of the phonological short-term memory.

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  • Pressman, P., and M. L. Gorno-Tempini. 2016. Logopenic variant of primary progressive aphasia. In The Behavioral neurology of dementia. Edited by B. L. Miller and B. F. Boeve, 194–202. Cambridge, MA: Cambridge Univ. Press.

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    This book chapter provides a comprehensive description of the essential characteristics of the lvPPA syndrome, intended for clinicians, graduate students, and researchers.

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  • Rising, K., and P. M. Beeson. 2020. The logopenic variant of primary progressive aphasia. In Primary progressive aphasia and other frontotemporal dementias. Edited by R. L. Utianski, 19–44. San Diego, CA: Plural Publishing, Inc.

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    The chapter presents an up-to-date description of the lvPPA, including demographics data, disease mechanisms, key features, and differential diagnosis with nfvPPA, svPPA, and AD.

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Language Impairment in Atypical Parkinsonian Syndromes

AD is the most common neurodegenerative cause of dementia and accounts for between 55 and 75 percent of all cases of dementia. Other forms of dementia, other than those already presented, may also cause language impairment. The most common neurodegenerative cause of parkinsonism (bradykinesia or akinesia, resting tremor, muscular rigidity, postural instability) is Parkinson’s disease. However, a significant number of individuals present with atypical features of Parkinson’s disease, including early dementia. These clinical presentations are grouped under the term “atypical parkinsonian syndromes.” Among these syndromes, dementia with Lewy bodies (DLB) and corticobasal degeneration (CBD) are associated with cognitive and language impairment. According to McKeith, et al. 2017, DLB is the second most common type of progressive dementia after AD. Although language is considered largely preserved in DLB, Metzler-Baddeley 2007 shows that the impairment of semantic memory may cause difficulties in word comprehension and word production, while Fields 2017 reports difficulty in verbal fluency and picture naming. Armstrong, et al. 2013 proposes diagnosis criteria for CBD, another atypical parkinsonian syndrome characterized by asymmetric motor symptoms (parkinsonism, dystonia, and myoclonus) and cognitive impairment. According to Machado De Oliveira, et al. 2017, the cognitive impairment associated with CBD includes deficit in visual spatial abilities, executive functions, memory, and language.

  • Armstrong, M. J., I. Litvan, A. E. Lang, et al. 2013. Criteria for the diagnosis of corticobasal degeneration. Neurology 80.5: 496–503.

    DOI: 10.1212/WNL.0b013e31827f0fd1Save Citation »Export Citation » Share Citation »

    In this article, an international consortium of neurologists, neuropsychologists, and movement disorders specialists present criteria for the diagnosis of CBD. These consensual criteria, established on the base of a systematic literature review, include the typical clinical features (motor and higher cortical features) and the different phenotypes of the syndrome.

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  • Burrell, J. R., J. R. Hodges, and J. B. Rowe. 2014. Cognition in corticobasal syndrome and progressive supranuclear palsy: A review. Movement Disorders 29.5: 684–693.

    DOI: 10.1002/mds.25872Save Citation »Export Citation » Share Citation »

    This review article focuses on multi-domain cognitive impairment in CBD. The impairments affecting executive functions are not specific to CBD and are therefore not very useful to the differential diagnosis. By contrast, the impairment of language, visuo-spatial function, and social cognition are more distinctive characteristics of CBD.

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  • Fields, J. A. 2017. Cognitive and neuropsychiatric features in Parkinson’s and Lewy body dementias. Archives of Clinical Neuropsychology 32.7: 786–801.

    DOI: 10.1093/arclin/acx085Save Citation »Export Citation » Share Citation »

    This review focuses on the contrast between DLB and Parkinson’s disease dementia regarding cognitive and neuropsychiatric features. Concerning language, DLB has been shown to affect verbal fluency and picture naming abilities of the same magnitude as in Parkinson’s disease.

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  • Machado De Oliveira, L., I. Barcellos, H. A. G. Teive, and R. P. Munhoz. 2017. Cognitive dysfunction in corticobasal degeneration. Arquivos de Neuro-Psiquiatria 5.8: 570–579.

    DOI: 10.1590/0004-282X20170077Save Citation »Export Citation » Share Citation »

    In this article, the authors show that cognitive deficits often present as the initial symptoms of CBD. They describe the impairments affecting visuospatial functions, motor control (apraxia), executive functions, and memory. With respect to language, nonfluent aphasia, with verbal apraxia and agrammatism, is the most common presentation of CBD.

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  • McKeith, I. G., B. F. Boeve, D. W. Dickson, et al. 2017. Diagnosis and management of dementia with Lewy bodies: Fourth consensus report of the DLB Consortium. Neurology 89.1: 88–100.

    DOI: 10.1212/WNL.0000000000004058Save Citation »Export Citation » Share Citation »

    This article presents the DLB consensus criteria established by a consortium of clinicians and researchers. The clinical profile of the syndrome includes core (fluctuating cognition, visual hallucinations, REM sleep behavior disorder, and parkinsonism) and supportive (e.g., apathy, anxiety, and depression) features.

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  • Metzler-Baddeley, C. A. 2007. A review of cognitive impairments in dementia with Lewy bodies relative to Alzheimer’s disease and Parkinson’s disease with dementia. Cortex 43.5: 583–600.

    DOI: 10.1016/s0010-9452(08)70489-1Save Citation »Export Citation » Share Citation »

    This article reviews cognitive impairments in DLB and specifically targets the impairment of perception, attention and executive functions, and memory. Within memory functions, the retrieval of semantic knowledge appears to be compromised in DLB, due to primary language deficit or to the dysexecutive impairment.

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The Impairment of Written Language in Neurodegenerative Diseases

Graham 2000 finds that, in contrast with the extensive literature on spoken language deficits, much less is known about the impairment of written language abilities, especially writing, in neurodegenerative diseases. Studies on reading and writing impairments in AD reflect a lack of consistency in findings. While the standard clinical portrait of AD suggests that written language abilities are largely preserved in patients, other studies, such as Harnish and Neils-Strunjas 2008 and Neils-Strunjas, et al. 2006, show that different patterns of written language impairment may be observed in AD, especially according to the progression of the disease. It is difficult to establish a clear profile of reading and writing impairments in VaD and atypical parkinsonian syndromes. However, as Graham 2014 shows, the absence or presence of these impairments are part of the clinical profile of the three PPA variants.

  • Graham, N. L. 2000. Dysgraphia in dementia. Neurocase 6.5: 365–376.

    DOI: 10.1080/13554790008402708Save Citation »Export Citation » Share Citation »

    This article reviews the spelling deficits associated with the major types of neurodegenerative diseases, including AD, PPA (svPPA and nfvPPA), LBD, and VaD. The author concludes that dysgraphia may take varying forms, although some profiles are typical in some of these syndromes, therefore contributing to their differential diagnosis.

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  • Graham, N. L. 2014. Dysgraphia in primary progressive aphasia: Characterisation of impairments and therapy options. Aphasiology 28.8–9: 1092–1111.

    DOI: 10.1080/02687038.2013.869308Save Citation »Export Citation » Share Citation »

    In this review article, the author provides a survey of spelling and handwriting impairments in each of the three variants of PPA. The functional origin of these impairments is also discussed in light of the cognitive and the connectionist models of reading.

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  • Harnish, S. M., and J. Neils-Strunjas. 2008. In search of meaning: Reading and writing in Alzheimer’s disease. Seminars in Speech and Language 29.1: 44–59.

    DOI: 10.1055/s-2008-1061624Save Citation »Export Citation » Share Citation »

    The profile of reading and writing impairments associated with AD are described in this review article and are compared to those observed in the svPPA. The theoretical reading and spelling models are summarized and used to identify the functional locus of the written language impairments in AD.

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  • Neils-Strunjas, J., K. Groves-Wright, P. Mashima, and S. Harnish. 2006. Dysgraphia in Alzheimer’s disease: A review for clinical and research purposes. Journal of Speech, Language, and Hearing Research 49: 1313–1330.

    DOI: 10.1044/1092-4388(2006/094)Save Citation »Export Citation » Share Citation »

    This comprehensive article presents a critical review of literature on dysgraphia associated with AD. The authors review dysgraphia in AD due to central spelling process impairment (lexical, phonological, semantic dysgraphia), due to impairment of nonlinguistic cognitive functions (attentional and executive deficit), and due to peripheral impairments of the writing system (i.e., motor aspects of writing).

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