Assessment of Language Function in Dementia

David F. Tang-Wai, MDCM, FRCPC; Naida L. Graham, PhD


Geriatrics and Aging. 2008;11(2):103-110. 

In This Article

Abstract and Introduction

Impairment in language is a common finding among individuals with dementia and can be a presenting symptom, particularly in Alzheimer's dementia and primary progressive aphasia. Early recognition of language dysfunction can help with an accurate diagnosis, management, and prognosis. There are numerous established and validated language evaluation protocols. This article provides a simple means for the primary care physician to identify and evaluate language disorders in dementia, but it is not meant to replace established protocols.

Language is the ability to encode ideas into words or symbols for communication to someone else[1] and involves speaking, comprehending, reading, and writing. Language should be differentiated from speech, which is the motor aspect of spoken language production.[2] Impairments in speech arise from any process that disrupts the neuraxis from the cortex to muscle and encompass dysarthria (disturbance in articulation) and dysphonia (disturbance in the production of vocal sounds).

Aphasia is an acquired language impairment caused by damage to the brain. It may involve language production, comprehension, or both. Although stroke is the most common cause of aphasia seen in general practice, progressive aphasias can occur in different dementing syndromes. The aphasic syndromes caused by stroke (outlined in Figure 1) bear a resemblance to those associated with neurodegenerative disease, but the terms used to describe stroke aphasia are not generally used to describe language impairments in dementia (with the possible exception of transcortical sensory aphasia). In addition, the brain areas affected are usually more localized in aphasia caused by stroke than in dementia.[3]

Clinical Description and Localization of Some Aphasias Caused by Stroke

Identification of language impairment is important in dementia because it aids in the accurate diagnosis of a specific type of dementia, alters the prognosis, and changes the management. The language impairment can be missed–this frequently leads to misdiagnosis.[4]


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