Dementia and Language

by

Joël Macoir

• LAST REVIEWED: 14 September 2023
• 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.

  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).

• 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/B978-008045352-1.00027-6

  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.

• 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.

  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.

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

  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.

• 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.2010.04.011

  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.

• 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.ch12

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

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

  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.