Language Disorders: Aphasia H A Whitaker, Northern Michigan University, by paraphasias, word finding difficulty, and variably Marquette, WI, USA impaired comprehension, associated with distur- & 2007 Elsevier Inc. All rights reserved. bance of reading and writing, at times with This article is a revision of ‘Aphasia Syndromes’ in dysarthria, non-verbal constructional, and problem- Encyclopedia of Language and Linguistics, 2nd edition, solving difficulty and impairment of gesture.’’ Good- volume 1, pp 321–327, Copyright 2006, Elsevier Ltd. glass and Kaplan (1983: p. 5) defined aphasia as ‘‘the disturbance of any or all of the skills, associations and habits of spoken or written language produced Glossary by injury to certain brain areas that are specialized Agrammatism – Characterized by articles, auxiliary for these functions.’’ Basso and Cubelli (1999: verbs and some prepositions omitted or unrecogni- p. 181) defined aphasia as ‘‘a disorder of verbal zed in speech and writing. communication due to an acquired lesion of the cen- tral nervous system, involving one or more aspects of Agraphia – Characterized by an inability to produce the processes of comprehending and producing written language. verbal messages.’’ Implicit in these definitions, of Alexia – Characterized by an impaired ability to course, is a definition of language, itself a relatively recognize words and/or letters, thus affecting the complex concept. ability to extract meaning from written text. The clinical syndromes of aphasia have been as- sociated with particular anatomical loci in the central Anomia – Characterized by a struggle to find appropri- nervous system in the literature since the nineteenth ate words in naming items and conversational speech. century. Contemporary research, particularly aided Anomic Aphasia (also known as amnestic aphasia, with the used of modern brain-imaging techniques, nominal aphasia, and semantic aphasia) – Charac- suggests that in addition to the so-called classical terized by a failure to name or to retrieve names, language areas of the dominant (usually, left) hemi- and common and proper nouns in speech. sphere’s cortex (Broca’s area, Wernicke’s area, etc.), many other areas of the central nervous system Apraxia (also called aphemia) – Characterized by participate in language processing, including subcor- errors in the selection or ordering of sounds such tical structures (including the basal ganglia, cerebel- that resulting erroneous words sound like the lum and thalamus), other cortical areas of the target word but have the wrong meaning or are so dominant hemisphere (including inferior and mesial distorted as to be non-words. temporal lobe and insula) as well as various regions Broca’s Aphasia (also known as verbal aphasia, ex- of the non-dominant hemisphere. This article focuses pressive aphasia, and motor aphasia) –Characterized on aphasia as a behavior and not its anatomical by speech output exhibiting poorly articulated substrate. words with missing, added, or transposed sounds, difficulty initiating speech, and reduced vocabulary. Approaches Conduction Aphasia (also called central aphasia, In broad outline, there are two approaches to un- repetition aphasia, and afferent motor aphasia) – derstanding the nature of aphasia. The first is con- Characterized by the repetition of individual cerned with functional components, what people do sounds or words in speech. when engaged in language behaviors; the four mo- Global Aphasia (also called total aphasia) – Character- dalities of language – speaking, listening, reading, ized by equal impairment of all language modalities. and writing – are examples of functional compo- nents. Other functional components of language in- Wernicke’s Aphasia (also called syntactic aphasia, sen- clude being able to repeat what is said, initiating sory aphasia, and receptive aphasia) – Characterized by speech, speaking fluently, being able to name things impairment in the understanding of spoken language. and people, and being able to clearly articulate words. This approach to aphasia has typically been clinical; identifying impaired functional components Introduction of language in conjunction with impairments in one or more of the four modalities has led to a clinical Kertesz (1979: p. 2) defined aphasia as ‘‘a neurologic- classification of the aphasias that is used in assess- ally central disturbance of language characterized ment, rehabilitation, and research. An active area of 10 Language Disorders: Aphasia research in this approach has been correlating the naming. Although comprehension is noticeably better loci of brain lesions with functionally identified than production, some patients with Broca’s aphasia syndromes of aphasia. have difficulty comprehending less frequent syntactic The second approach might be termed neuro- structures, although most demonstrate the ability to linguistic; it is concerned with the structure comprehend single nouns, verbs, or adjectives. Errors of language and which linguistic structures are may occur in word order, which is called paragram- impaired in aphasia. This approach begins with ana- matism, but this is more common to Wernicke’s lyses of aphasic language in terms of linguistic levels aphasia (discussed next). Nouns tend to be preserved – phonological, morphological, syntactic, semantic, better than verbs and adjectives in Broca’s aphasia, and discourse – and then may take either an exper- but grammatical function words are the most im- imental or applied tack, correlating linguistic deficits, paired. A concomitant of the shorter phrases and fre- brain lesions, and clinical syndromes. The neuro- quent pauses seen in Broca’s aphasia is an impairment linguistic approach typically furnishes linguistic de- in prosody, alterations such as impaired inflection, tails to the functional-clinical approach, particularly pitch, and rhythm; this is commonly referred to as in research applications. dysprosody. Repetition often shows the same impair- Studying the localization of lesions that cause ments as in conversational speech. Writing in Broca’s aphasia was at one time of major clinical impor- aphasia tends to be impaired analogously to speech tance; modern imaging techniques, applied to both output, but reading ability may be only mildly im- brain-damaged aphasic patients and non-brain- paired; writing will exhibit misspellings, letter omis- damaged experimental subjects, have shifted empha- sions, poor formation of letters, and agrammatism. sis to questions of which parts of the brain subserve Patients with Broca’s aphasia are generally more which language functions and/or which language aware that their speech and language is impaired than structures. A reasonable goal would be to identify a those with Wernicke’s aphasia and thus may struggle unique brain structure and its connections, damage to produce more correct responses. to which caused a well-defined clinical aphasia The lesions typically leading to Broca’s aphasia syndrome and a well-defined linguistic impairment. most often affect both the inferior frontal lobe and the anterior inferior portion of the parietal lobe; this is generally more extensive than the part of the third Functional-Clinical Aphasia Syndromes (inferior) frontal gyrus and surrounds that have been identified as Broca’s area. Broca’s Aphasia Broca’s aphasia has also been called verbal aphasia, Wernicke’s Aphasia expressive aphasia, efferent motor aphasia, and motor aphasia. The primary modality of language that is Wernicke’s aphasia has also been called syntactic affected is speech production, but writing is often af- aphasia, acoustic aphasia, sensory aphasia, and re- fected, too. Comprehension of spoken language and ceptive aphasia. The primary modality of language reading are usually much better preserved. According that is affected is speech perception, and reading may to the older scheme of dividing the aphasias into flu- be affected, too. The ability to produce speech and ent and non-fluent, Broca’s aphasia is the common the ability to write are usually much better preserved, variant of non-fluent aphasia. Speech output tends to although the content of speech and writing will likely exhibit poorly articulated words with missing, added, be impaired. According to the older scheme of or transposed sounds, and there is usually difficulty in dividing the aphasias into fluent and non-fluent, Wer- initiating speech. The range of vocabulary is often nicke’s aphasia is the common variant of fluent apha- reduced from premorbid levels, and speech output sia. The salient feature of Wernicke’s aphasia is an tends to rely a great deal on basic, highly familiar, and impairment in understanding spoken language, par- thus overlearned speech patterns. Speech is likely to ticularly when the content of the spoken language is be in short phrases with fewer words than expected, not predictable from the context or not otherwise punctuated with frequent pauses. Commonly seen in highly familiar. In milder forms, comprehension may Broca’s aphasia is agrammatism, speech and writing be contextually appropriate, e.g., a discussion of the in which the small elements of grammatical structure, weather, but lacking in details, e.g., unable to dis- typically the so-called function words such as articles, tinguish partially cloudy from overcast. On the other auxiliary verbs, and some prepositions, are omitted or hand, the speech of the Wernicke’s aphasic patient unrecognized. Anomia is also fairly common, causing may appear articulatorily fluent but paraphasic, that patients to struggle with finding the appropriate word, is, an intrusion of non-words, words out of order, and both in conversational speech and in confrontational word choices that are marginally related or unrelated Language Disorders: Aphasia 11 to the topic of the conversation. Paraphasias may (substitution of sounds) may intrude in both sponta- appear in any variety of aphasia, but they are typi- neous speaking and in attempts to repeat what is cally more prevalent in Wernicke’s aphasia. As in heard. Within single words or very short phrases, Broca’s aphasia, grammar may be affected, rather articulatory fluency may be good, but patients than function words being omitted, they are more with conduction aphasia typically display phonemic likely to be used improperly or added extraneously. (or literal) paraphasias, a substitution of sounds. Grammatical word order constraints may be violated, Although within-phrase syntactic patterns tend to be a syntactic impairment called paragrammatism. Wer- normal, many conduction aphasic patients have dif- nicke’s aphasic patients are not likely to use complex ficulty with sentences containing pronouns and gram- sentence structure but rather will resort to simple, matical function words, as well as polysyllabic words. common declarative word order. Occasionally, pa- Other characteristics that may be found include dif- tients with Wernicke’s aphasia may talk excessively, ficulties in writing, showing some forms of agraphia even to the point of adding unrecognizable syllables, and ideomotor apraxia. Writing ability usually par- words, or phrases to their speech, a phenomenon allels speech output, showing deficits in spelling and known as jargon aphasia. Most researchers consider letter omissions or substitutions. As is the case for jargon aphasia to be a subtype of Wernicke’s aphasia. Broca’s aphasia, conduction aphasic patients are typi- In jargon aphasia, the jargon aphasic errors may be cally aware of their speech and language deficits. literal (single sounds), verbal (added words that are The lesions leading to conduction aphasia tend to recognizable), or neologistic (added words that be located in and around the supramarginal gyrus are unrecognizable). The patient with Wernicke’s and the arcuate fasciculus; the latter pathway con- aphasia may be able to write letters and words cor- nects the temporal lobe to the frontal lobe. Other rectly as a motor action, but the output reflects the lesions are along the border of the Sylvian fissure, patient’s fluent paraphasic speech, including a di- extending to the subjacent white matter. sorganized and rambling style, occasional to frequent repetitions of words or phrases, jargon aphasic errors, Anomic Aphasia and a lack of recognizable content. Reading tends Anomic aphasia is also known as amnestic or amnesic to follow auditory comprehension ability, typically aphasia, nominal aphasia, and semantic aphasia. The impaired. primary modality of language that is affected is speech The lesions responsible for Wernicke’s aphasia are production, restricted to the production of names, but typically in the middle to posterior temporal lobe, it is most easily observed by asking an aphasic patient particularly the superior gyrus, but frequently the to name an object, so an input problem cannot be middle temporal gyrus as well. These lesions often excluded. Anomia is described by the failure to name continue back to the junctions of the temporal lobe or to retrieve names, common and proper nouns; au- with the occipital and inferior parietal lobes, in the ditory comprehension is either unimpaired or only areas named the supramarginal and angular gyri. mildly impaired. One manifestation of anomic speech is a fluent output that lacks the nouns and verbs re- Conduction Aphasia lated to concepts. As a result, speech may be described as empty. Speech rate, articulation, and, surprisingly, Conduction aphasia has also been called central grammar are typically normal, and the on-line deficits aphasia, disorganized execution of the encoding in word retrieval may be signaled by noticeable program related to disturbed auditory feedback, rep- pauses. Accompanying impaired naming is the inabil- etition aphasia, and afferent motor aphasia. The ity to comprehend nouns or verbs in isolation; primary function of language that is affected is the however, object recognition is usually quite good. Al- repetition of speech, whereas comprehension and though reading and writing are usually preserved, in production tend to be much less impaired. Conduc- severe cases of anomia there may be an anomic alexia tion aphasic patients frequently attempt to correct or anomic agraphia. Some degree of anomia is found their repetition errors, implying a better preserved in virtually all varieties of aphasia; in part for that comprehension. The repetition errors may be at the reason, no specific localization for the causative le- level of individual sounds or words; repetition may sions has been or is likely to be documented. exhibit an agrammatic character. The speech of the patient with conduction aphasia is more often like Global Aphasia that seen in Wernicke’s aphasia but sometimes is like that seen in Broca’s aphasia. In addition to the rep- Global aphasia has also been called total aphasia. All etition deficit, patients with conduction aphasia language modalities are affected in global aphasia to are often afflicted with anomia; literal paraphasias an equal degree, unlike the other aphasias, in which a 12 Language Disorders: Aphasia processing disparity among the modalities is evident. sensory aphasia; the modality affected is hearing. It The causative lesions leading to global aphasia are causes patients to be unable to recognize speech typically very large, subtending all or most of sounds, while being able to hear non-language language cortex. environmental noises, animal sounds, and music. Other language modalities – speech production, read- ing, and writing – generally remain intact. Lesions Single-Modality Functional-Clinical typically leave Wernicke’s area undamaged, but de- Aphasia Syndromes stroy both Heschl’s gyrus (primary auditory cortex) in There are a number of aphasia syndromes that the language hemisphere and the afferent auditory predominantly affect a single language modality. pathways coming from the non-language hemisphere. The functional result is that Wernicke’s area behaves Apraxia of Speech as though it is isolated from auditory language input; the patient can hear but cannot understand or repeat Apraxia of speech has also been called aphemia, ver- speech sounds. Except for the severely impaired input bal apraxia, articulatory apraxia, and anarthria. Not processing of speech, the patient with pure word all researchers agree that this is an aphasia syndrome; deafness does not otherwise function like someone it is included here because, by definition, motor con- with Wernicke’s aphasia. Auditory agnosia, which trol of the speech musculature is not affected in ap- also reflects impaired processing of speech sounds, raxia of speech, in other words, it is independent of additionally reflects an impairment in processing dysarthria. Apraxia of speech often accompanies non-language environmental sounds. Broca’s aphasia but may be an independent, modal- ity-specific impairment. The modality affected is Agraphia speaking, and the problems are best described as er- rors in the selection or ordering of sounds such that Agraphia, an inability to produce written language, the resultant erroneous words either sound some- has several neurolinguistic variants, which are dis- thing like the target word but have the wrong mean- cussed later in the neurolinguistic structures section. ing or are so distorted that they are no longer words Functionally, it may appear as a written form of of the language. Broca’s aphasia and, since written language so often mirrors spoken language, is typically associated with Alexia with Agraphia an aphasia. But, because writing also includes vis- Alexia and agraphia are, respectively, input and output uospatial skills as well as motor skills that differ from impairments of written language. Alexia and agraphia speech, impairments in spatial orientation or visual may occur independently or together; alexia with discrimination can cause agraphia without aphasia. agraphia has also been called parietal-temporal alexia, Cases of pure agraphia frequently report damage central alexia, semantic alexia, angular alexia, and within the frontal lobe, but a few cases have also letter blindness. The primary modalities of language shown damage within the left superior parietal lobe. that are affected are reading and writing. Patients suf- fering from alexia with agraphia display impairments Alexia in both reading and writing skills. In general, their Alexia is an acquired reading problem exhibited as ability to copy words tends to be better preserved than an impaired ability to recognize words and/or letters, their spontaneous writing ability. The inability to read thus affecting the ability to extract meaning from and write extends into domains other than visual written text. There are several varieties of alexia, in- language: numbers, musical notation, and chemical cluding literal alexia (also referred to as letter blind- formulas can also be impaired. Speech output and ness because the problem is primarily with individual auditory comprehension may be somewhat impaired letters), verbal alexia (also referred to as word blind- but typically only in a mild form of anomia. Both the ness because whole words are primarily affected), location and the size of the lesion will strongly influ- general alexia (which refers to reading impairments ence the manifestation of any aphasia, but these are that affect grammatical and/or semantic processing particularly relevant in the impairment described as more than letters or words), and hemialexia, more alexia with agraphia; the causative lesions are pre- commonly called neglect alexia (which refers to the dominantly found in the region of the angular gyrus. impairment of attending to only half of a word or a line of text). In so-called pure alexia, written Pure Word Deafness language stimuli are seen but not recognized as Pure word deafness has also been called auditory letters, as words, or both. In these cases, lesions tend agnosia, isolated speech deafness, and subcortical to compromise the visual association cortex in the Language Disorders: Aphasia 13 language hemisphere together with the callosal may be paraphasic, neologistic, anomic, and even fibers projecting from the other hemisphere, echolalic. Typical output may appear to be uninhib- effectively isolating central language brain areas ited. Patients with transcortical sensory aphasia from visual input. There is a variant of pure alexia typically tend to be unaware of their impairment; called letter-by-letter reading; such patients seem to as might be expected, their speech is occasionally process words by reading one letter at a time aloud misinterpreted as a psychogenic problem, such as before the word is identified. In some cases of alexia schizophrenia. Writing ability is usually disturbed in patients may successfully comprehend words if they a manner similar to that of patients with Wernicke are spelled out loud or traced on the palm, thus by- aphasia. passing visual input to access the language core brain regions. Transcortical Motor Aphasia Transcortical motor aphasia, another form of the transcortical aphasias, Transcortical Aphasias is sometimes known as dynamic aphasia or anterior isolation syndrome. Functionally, the causal lesion The transcortical aphasias are sometimes known as separates the processing of speech from the mecha- the echolalic aphasias; there are three types, trans- nisms for initiating the action to speak. Patients with cortical sensory, transcortical motor, and mixed transcortical motor aphasia tend to appear mute, or transcortical, the latter sometimes known as the iso- nearly so, and may even have an associated general lation syndrome. The modalities of language that akinesia, an inability to initiate action. Although are affected are speech comprehension (transcortical transcortical motor aphasia impairs the ability to in- sensory) and speech production (transcortical motor) itiate speech, once such patients begin talking, speech in the context of a sometimes dramatic spared ability output is typically relatively intact. Comprehension to repeat, thus contrasting with conduction aphasia. will be relatively normal, as will repetition. Prosody, In discussing the transcortical aphasias, it is useful to articulation, and grammatical structure remain quite consider the notion of the language core, the tempo- preserved even if verbal output is interrupted by ro-parieto-frontal cortex of the language-dominant incomplete sentences, verbal paraphasias, or false hemisphere in which resides the ability to repeat starts. When asked to say something, or otherwise what is heard as well as the ability to process the initiate a response without cues, these patients have a basic sounds and word and sentence structures of great deal of difficulty responding; however, when one’s language. Originally, the term transcortical asked to repeat words, phrases, or sentences, meant that an ability to reproduce the sound struc- performance is characteristically flawless. There is a ture or representation of a word was preserved, in range in ability in word retrieval, with some patients the context of being unable to construct its meaning; being able to perform well on tasks such as object this could be considered analogous to an ability to naming. Verbal output may improve if related to repeat a word in a foreign language that one does not common, repetitious material. The lesions that lead understand. The predominant anatomically dis- to transcortical motor aphasia are typically found on tinguishing feature of these aphasias is that the the mesial surface of the anterior left frontal lobe, causative lesions are largely extra-Sylvian in location, near supplementary motor cortex, or along the lat- that is, outside the classic language core. The fol- eral aspect of the left frontal lobe; in either case these lowing provides a brief overview of the generally lesions fall outside of what is traditionally thought of accepted classical forms of the transcortical aphasias. as Broca’s area. Presumably the lesions impinge on an anterior cortical or subcortical site that forms part Transcortical Sensory Aphasia Transcortical sen- of a circuit linking the motor speech area with the sory aphasia is an uncommon form of aphasia that supplementary motor area and certain limbic struc- may occur when a lesion functionally isolates Wer- tures considered essential for the initiation of speech nicke’s areas from the rest of the brain, leaving the and other actions. reception-to-output sufficiently unimpaired that rep- etition is preserved; neither speech comprehension Mixed Transcortical Aphasia Mixed transcortical nor spontaneous speech remain intact. The simplest aphasia, known also as the isolation syndrome, may way to describe transcortical sensory aphasia is to be associated with Pick’s disease or carbon monoxide think of it as a form of Wernicke’s aphasia in which poisoning affecting the so-called watershed region the patient exhibits a severe comprehension deficit, of the cerebral vasculature; the language core, the but in which repetition, and thus articulation, is well peri-Sylvan speech areas, are functionally isolated preserved. In spite of intact articulation, the repeated from other brain functions, particularly higher-order speech of the transcortical sensory aphasic patient cognitive functions. The one remaining language 14 Language Disorders: Aphasia function is a striking ability to repeat words, phrases, was intended, or speech may be louder or quieter at and on occasion whole sentences. The isolation inappropriate times. syndrome is most clearly the functional opposite of conduction aphasia; the former patient can only re- Morphological Disorders peat speech, while the latter cannot repeat speech. Morphological disorders affect a word’s affixes, either Although articulatory fluency generally remains well (a) the inflectional affixes such as mark plural vs. preserved, the quasi-automatic repetition, often a singular, third person singular vs. first person singular, frank echolalia, is prominent in a context of few if or past vs. present tense (e.g., three cat for three cats, any other intact language functions. There is typi- he will jumped for he will jump) or (b) the deriva- cally a complete alexia and agraphia, with an occa- tional affixes such as mark words as nouns, verbs, or sional ability to scribble meaninglessly. As pointed adjectives (e.g., nationalness for nationality). out by Benson and Ardila, other than the ability to repeat, patients with mixed transcortical aphasia Syntactic Disorders exhibit the characteristics common to global aphasia. Syntactic disorders, agrammatism, affect the gram- matical structure of phrases and sentences. Obvi- Neurolinguistic Structures ously, if disorders of derivational or inflectional affixes discussed previously were to impact the gram- The second approach, a neurolinguistic analysis of the matical correctness of a phrase or sentence (e.g., he’s aphasias, focuses on which linguistic components of a regularity guy for he’s a regular guy) one would language are affected by brain damage, within the speak of a syntactic deficit that manifested as a framework of five, sometimes six, components of morphological error. The more common form of language: (1) phonology, or the sound system, (2) agrammatism is seen as the omission of grammatical morphology, or the structure of words, (3) syntax, or function words (e.g., boy hit ball for the boy was hit the grammatical system, (4) semantics, or the system by the ball), which clearly impacts the meaning of the of meaning, (5) narrative or discourse, or the compo- sentence as well as its grammaticality; thus, as was nent that strings sentences together in coherent syn- the case with morphological disorders, syntactic dis- tactic and semantic structure, and (6) the pragmatic or orders can overlap semantic disorders, too. A rarer language use system. Linguistic-based descriptions of form of syntactic disorder known as paragrammatism aphasic errors are neutral as to whether the errors are results in the inappropriate use and ordering of gram- seen in speech production or comprehension or in matical function words, rather than their omission written language. It is typical that the degree of im- (e.g., in on a the by a flower pot for in the flower pot). pairment (percentage of errors seen on testing) of Additional syntactic disorders involve the simplifica- linguistic components is different in different language tion, ordering, substitution, or omission of phrase- modalities; for example, a Broca’s aphasic patient is and sentence-level structures that may interact with likely to exhibit more severe agrammatism in speaking impairments in meaning. For example, if what the pot than in comprehending. It is occasionally documented put on the table was the boy were substituted for it that the linguistic impairments are overwhelmingly in was the pot that the boy put on the table,or,what the one modality (e.g., being able to recognize gram- boy put on the table was the pot, one would note that matical errors but being unable to avoid producing the grammatical errors of substitution and ordering them); this can lead to interesting theoretical issues resulted in a change in meaning. As will be readily regarding the nature of the language core brain areas, surmised, agrammatism is frequently, though not which are beyond the scope of this article. exclusively, seen in Broca’s aphasia; paragrammatism is less frequently seen in Wernicke’s aphasia because Phonological Disorders word order violations are infrequently observed syn- Phonological disorders are typically described in tactic disorders. terms of phonemes, the minimal significant unit of Semantic Disorders sound in a language, or graphemes, the equivalent for the writing system. Errors may be described as Semantic disorders can take any number of forms, substitutions (e.g., bit for pit), omissions (e.g., cook depending upon what aspect of the semantic system is for crook), or sequencing errors (e.g., cattle for impaired. Substitution of similar-meaning words is tackle, as sounds). Other phonological errors include common (e.g., concert for orchestra) as is the inter- problems with the control of prosody: syllables may change of superordinates and subordinates (e.g., an- be shortened or lengthened incorrectly, pitch imal for dog). A common strategy for anomic patients contours may signal a question when a statement is to substitute an indefinite noun for an inaccessible Language Disorders: Aphasia 15 one (e.g., something or stuff in place of shirt or major problem with grapheme-to-phoneme convers- clothes). Semantic disorders may also impair know- ion, they have difficulty reading pronounceable ledge of features of objects (e.g., being unable to in- nonwords, as is the case with deep alexic patients. dicate that a fire truck is red or that grass is green) or Patients with phonological alexia typically do not attribute incorrect features to objects (e.g., something make the semantic errors seen in deep alexia; other- inanimate is given attributes of being alive). wise, the boundary between deep and phonological alexia is not always sharp and some patients seem to Narrative Disorders have many characteristics of both types. It has been Narrative or discourse disorders will affect the co- reported that deep alexia may evolve to phonological herent stringing of sentences or phrases together in alexia in the course of recovery. conversation, for example, changing a pronoun so Surface Alexia Patients with surface alexia have a that it no longer refers back to the person who is reading impairment characterized by their ability to being discussed or inappropriately changing the time read orthographically regular words (note that about frame of a narrative. Pragmatic disorders refer to im- 75% of the English lexicon is orthographically regular, pairments in language use, for example, no longer e.g., words such as top, jelly, sing) but a pronounced understanding that the statement ‘‘I could use some difficulty reading orthographically irregular words (in salt on my roast beef’’ is an indirect request to another English, words such as pint, come, bury are orthogra- person to pass the salt shaker to the speaker. It will be phically irregular). Errors made by surface alexic immediately apparent that, just as with morph- patients on irregular words tend to be regularizing er- ological and syntactic disorders, higher level prob- rors, that is, pronouncing them as though they were lems with discourse and pragmatics may be described orthographically regular. Surface alexic patients are in terms of semantic or syntactic errors. The different able to read pronounceable nonwords, e.g., heaf linguistic components of language, levels, are simul- would be read to rhyme with the word leaf, which is taneously present when language is being used. regular, but not deaf, which is irregular.
Alexias Agraphic Disorders The analysis of neurolinguistic structures has led to a As with reading impairments, there are three main syndrome classification of reading and writing dis- linguistic forms of agraphic disorders. The first is orders as follows. Three alexias have been defined in phonological agraphia, which is an impairment in terms of the putative locus in a psycholinguistic writing pronounceable pseudowords to dictation, model of reading: deep alexia, phonological alexia, with a much better preserved ability to write real and surface alexia. words and occasional difficulties with grammatical function words and abstract words. A second form is Deep Alexia Patients with deep alexia usually have semantic agraphia, which can occur with focal lesions sustained a lesion sufficiently large to produce an but is more commonly found in the early stages of aphasia, frequently a Broca’s aphasia; their reading is senile dementia of the Alzheimer type; such patients characterized by semantic errors in reading aloud may write real words and pseudowords normally to (the error is semantically related to the target word) dictation, but they make frequent semantic errors in and may also show visual errors (the error is visually written confrontation naming or written descriptions. similar but otherwise unrelated to the target word), A third form is lexical agraphia; these patients morphological errors (the error is a morphological preserve the phonological form of the word when variant of the target word), a concreteness effect writing, but produce spelling errors that normalize (concrete words are easier to read than abstract spelling to approximate to how the word sounds. ones), and difficulty in reading grammatical function words. Word frequency and word length may also Conclusion impact the prevalence of reading errors. Patients with In conclusion, the main recommendations today for deep alexia are impaired in grapheme-to-phoneme continued use of the functional/clinical aphasia syn- conversion; as a result, they have a pronounced dromes, the so-called classical syndromes, reviewed inability to read non-word letter strings that could be here are convenience and consistency. A great deal of possible words in the native language (e.g., for modern research in neurolinguistics, clinical neuro- English, the string vib or phite). psychology, and the cognitive neurosciences employs the classical aphasia syndromes for identifying Phonological Alexia Phonological alexic patients patient groups, notwithstanding the research in can read real words but because they also have a the late twentieth century that casts doubt upon the 16 Language Disorders: General validity of the consistent location of causative le- Clinical and Experimental Neuropsychology, pp. sions, other research that questions the logical co- 181–193. East Sussex, UK: Psychology Press. herence of the symptomatology of syndromes, and Benson FD and Ardila A (1996) Aphasia: A Clinical still other research that questions the possibility of Perspective. New York: Oxford University Press. Caplan D (2000) Aphasia. In: Kazdin AE (ed.) Encyclope- studying groups of patients classified in terms of dia of Psychology. Washington, DC: American Psycho- these syndromes. The most widely used test battery logical Association. in the United States, the Boston Diagnostic Aphasia Coltheart M (ed.) (1996) Phonological dyslexia. Special Examination (BDAE), from which the major aphasia issue of the Journal of Cognitive Neuropsychology syndrome typology originates, claims to be able to (September). classify only about three-fourths of all patients Coltheart M, Patterson K, and Marshall JC (eds.) with language impairments. One may still argue, (1980) Deep Dyslexia. London: Routledge and Kegan Paul. and many contemporary publications will attest, Gonzalez-Rothi LJ (1997) Transcortical motor, sensory, that the patients who can be so classified into syn- and mixed aphasia. In: LaPointe LL (ed.) Aphasia and dromes can, sensibly and statistically, be grouped Related Neurogenic Language Disorders, 2nd edn. New under these headings for research purposes. In York: Thieme. contrast, a linguistic typology of aphasia, a classifi- Goodglass H (1993) Understanding Aphasia. San Diego, cation of neurolinguistic impairments, would only be CA: Academic Press Inc. challenged by a better linguistic theory. Such a clas- Goodglass H and Kaplan E (eds.) (1983) The Assessment of Aphasia and Related Disorders, 2nd edn. Philadel- sification does characterize aphasic impairments even phia, PA: Lea & Febiger. if it does not neatly align with functional and clinical Kaplan E, Gallagher RE, and Glosser G (1998). Aphasia- categories, nor does it neatly align with particular related disorders. In: Sarno MT (ed.) Acquired Aphasia, brain regions as revealed by lesion localization or 3rd edn. San Diego, CA: Academic Press. imaging techniques. Caveat emptor. Kertesz A (1979) Aphasia and Associated Disorders. New York: Grune and Stratton. See also: Language and Communication in Aging; Patterson K, Marshall JC, and Coltheart M (eds.) (1985) Language Disorders: General; Speech and Communica- Surface Dyslexia: Cognitive and Neuropsychological tion (speech styles). Studies of Phonological Reading. London: Lawrence Erlbaum Associates. Pratt N and Whitaker HA (2006) Aphasia syndromes. In: Further Reading Encyclopedia of Language and Linguistics, 2nd edn. Amsterdam: Elsevier. Basso A and Cubelli R (1999) Clinical aspects of aphasia. Whitaker H and Whitaker HA (eds.) (1976) Studies in In: Denes G and Pizzamigliio L (eds.) Handbook of Neurolinguistics, vol. 1. New York: Academic Press.
Language Disorders: General and abstract thinking, as well as changes in per- M Goral, Boston University School of Medicine, sonality. Boston, MA, USA, and City University of New York Discourse Skills – Skills allowing the appropriate use Graduate Center, New York, NY, USA of pronouns, intonation patterns, and meeting M R Clark-Cotton and M L Albert, Boston University School of Medicine, Boston, MA, USA social expectations in conversation. Lexical Skills – Skills that relate to the production Published 2007 by Elsevier Inc. and comprehension of individual words. Syntactic Skills – Skills that enable a person to un- derstand and use conventional rules of grammar. Glossary Aphasia – Acquired, usually abrupt-onset language impairment resulting from brain damage. Overview of Language Disorders in Older Adults Dementia – Acquired disorder of cognitive and self-management abilities, that may be character- Language disorders in older adulthood can be ized by progressive decline of memory, judgment, generally divided into progressive impairments of