Motor speech disorders associated with primary progressive aphasia

Background: Primary progressive aphasia (PPA) and conditions that overlap with it can be accompanied by motor speech disorders. Recognition and understanding of motor speech disorders can contribute to a fuller clinical understanding of PPA and its management as well as its localisation and underlying pathology.

Aims: To review the types of motor speech disorders that may occur with PPA, its primary variants, and its overlap syndromes (progressive supranuclear palsy syndrome, corticobasal syndrome, motor neuron disease), as well as with primary progressive apraxia of speech.

Main Contribution: The review should assist clinicians’ and researchers’ understanding of the relationship between motor speech disorders and PPA and its major variants. It also highlights the importance of recognising neurodegenerative apraxia of speech as a condition that can occur with little or no evidence of aphasia.

Conclusion: Motor speech disorders can occur with PPA. Their recognition can contribute to clinical diagnosis and management of PPA and to understanding and predicting the localisation and pathology associated with PPA variants and conditions that can overlap with them.     

Biomarkers in the primary progressive aphasias

Background: Primary progressive aphasia (PPA) is a progressive disorder of language that is increasingly recognised as an important presentation of a specific spectrum of neurodegenerative conditions.

Aims: In an era of etiologically specific treatments for neurodegenerative conditions, it is crucial to establish the histopathologic basis for PPA. In this review, I discuss biomarkers for identifying the pathology underlying PPA.

Main Contribution: Clinical syndromes suggest a probabilistic association between a specific PPA variant and an underlying pathology, but there are also many exceptions. A considerable body of work with biomarkers is now emerging as an important addition to clinical diagnosis. I review genetic, neuroimaging and biofluid studies that can help determine the pathologic basis for PPA.

Conclusions: Together with careful clinical examination, there is great promise that supplemental biomarker assessments will lead to accurate diagnosis of the pathology associated with PPA during life and serve as the basis for clinical trials in this spectrum of disease.     

Word retrieval therapies in primary progressive aphasia

Background: Primary progressive aphasia (PPA) with its three variants is a progressive neurodegenerative dementia in which language impairment is the first and most dominant symptom. Traditionally, speech-language pathologists who deliver therapy to adults with acquired neurogenic language disorders shy away from treatment of progressive aphasia as there is no promise of lasting effects and only limited data regarding treatment efficacy.

Aims: This paper comprises the most current review of the literature focused on treatment of naming impairments in PPA, and aims to encourage and assist clinicians in selecting intervention approaches for individuals with PPA. It highlights current trends and challenges in delivering successful therapy for naming deficits in PPA.

Main Contribution: We reviewed papers that reported different forms of naming therapy for patients with PPA, which included interventions that, although not always aimed directly at anomic deficits, brought about improvement in naming. Immediate gains, maintenance, and generalisation effects are summarised, along with a variety of approaches and methodologies that can be applied to the PPA population. We also provide a list of factors that were found to contribute to the success of therapy and to the maintenance and/or generalisation of treatment gains.

Conclusions: Current literature delivers encouraging evidence for clinicians wanting to provide naming therapy to patients with PPA. Although PPA is a progressive disorder, both the immediate treatment effects and, in many cases, maintenance results show that improvements are possible. The issues of generalisation of naming gains beyond the clinician’s office still require more studies to determine the best conditions, designs, and patient suitability.     

Therapy for naming deficits in two variants of primary progressive aphasia

Background: Primary progressive aphasia (PPA) refers to a progressive and selective decline in language due to neurodegenerative disease. There are three variants of PPA, progressive nonfluent aphasia (PNFA), semantic dementia (SD), and logopaenic progressive aphasia (LPA). All variants include impaired object naming, but distinct underlying deficits might interfere with naming. Therefore, individuals with different types of PPA may respond differently to naming therapy.

Aims: To identify differences in patterns of success and generalisation in response to the same treatment in patient with LPA and a patient with SD. Furthermore, we wished to identify whether the treatment effect was item specific (trained words) or generalised to untrained words in trained or untrained categories.

Methods & Procedures: Participants included an individual with LPA and one with SD. An assessment of lexical processing was administered before and after a naming treatment to assess underlying deficits and generalisation effects. Therapy consisted of a cueing hierarchy treatment. Treatment items consisted of pictured objects in the categories of fruits/vegetables and clothing.

Outcomes & Results: Two different patterns of performance were observed. The LPA participant improved in naming of treated items and untreated items in both treated and untreated categories. The participant with SD improved in naming treated items only, but showed less deterioration in untreated items in treated than untreated categories.

Conclusions: Individuals with PPA can show improved naming (at least temporarily) with therapy, but generalisation to untrained items may depend on the underlying cause of the naming deficit, which may differ across subtypes.     

Trouble and repair during conversations of people with primary progressive aphasia

Background: Primary progressive aphasia (PPA) affects a range of language domains that impact on communication. Little is known about the nature of conversation breakdown in PPA. The identification of trouble in conversation, its repair and the success of repairs has been used effectively to examine conversation breakdown in neurogenic language disorders such as dementia of the Alzheimer type (DAT) and acute onset aphasia. This study investigated trouble and repair in the conversations of people with PPA.

Aims: The first aim of this study is to describe the contributions of individuals with PPA and their conversation partner to conversation. The second aim is to describe the trouble that occurs in dyadic conversations between three individuals with PPA and their communication partner. The third aim is to describe the repair behaviours used by the individuals with PPA and their communication partners.

Methods & Procedures: Dyadic conversations about everyday activities between three individuals with PPA and their partners and three control dyads were video recorded and transcribed. Number of words, number of turns and length of turns were measured and trouble-indicating behaviours (TIBs) and repair behaviours were categorised.

Outcomes & Results: Individuals with PPA had reduced mean length of turn but maintained their share of turn-taking. They demonstrated a variety of TIBs that differed from the noninteractive repairs, which do not require a response from the partner in the conversation and which have been observed in studies of conversation in DAT. Their partners bore the greater burden of highlighting trouble and need for repair using collaborative, interactive, TIBs. Three different conversational profiles were observed in the three PPA dyads, reflecting different patterns of language and cognitive impairment.

Conclusions: Individuals with PPA were active participants in conversation effectively indicating and responding to trouble. Understanding trouble and repair in the conversations of individuals with PPA has the potential to enhance assessment and inform clinical practice.     

Long-term follow-up in primary progressive aphasia: Clinical course and health care utilisation

Background: Primary progressive aphasia (PPA) is a rare disorder. Data on health care utilisation and care-relevant symptoms are scarce.

Aims: The study aimed at finding out how patients with PPA are cared for, the extent of professional support utilised by family caregivers, and which care-relevant clinical symptoms and signs occur with advanced disease.

Method & Procedures: Forty-three family caregivers of patients with PPA were interviewed with a standardised questionnaire.

Outcomes & Results: A majority of caregivers cared for the patients at home without any support. More than 40% of the patients were treated with cholinesterase inhibitors or memantine. Only 9% of the patients received speech therapy. In advanced PPA, the majority of patients were unable to communicate and almost all needed 24-hr care. Other neurological symptoms appeared, and a considerable number of patients suffered from moderate or severe somatic illnesses.

Conclusion: Future studies are necessary to investigate the reasons why the PPA caregivers hardly utilise informal and formal support, what their specific needs are, and which kind of support and interventions prove to be useful.     

The patterns of progression in primary progressive aphasia—Implications for assessment and management

Background: Primary progressive aphasia (PPA) is a progressive language disorder with preserved cognitive function for at least 2 years from onset. The main variants currently distinguished are: non-fluent/agrammatic (nfvPPA), semantic (svPPA), and logopenic (lvPPA). Patients with initial language presentation may subsequently develop other symptoms, such as behavioural dysfunction or apraxia. The clinical pattern of PPA depends on the location of atrophy, the underlying pathology, and the stage of the disease.

Aims: This review aims at characterising longitudinal changes in clinical presentations of different PPA variants and at presenting implications of these changes for the assessment, diagnosis, and management.

Main contribution: The three PPA variants differ not only in terms of language impairment, but also with regard to cognitive and behavioural profile. Apraxia and rigidity frequently occur in the course of nfvPPA. Patients with lvPPA seem to follow the pattern of aphasic Alzheimer’s disease, where language impairment is accompanied by episodic memory deficit. Individuals diagnosed with svPPA often develop behavioural dysfunction similar to that observed in behavioural variant of frontotemporal dementia.

Conclusions: Implications for patient care are dependent on PPA variant and on the stage of the disease. In svPPA, emphasis should be on the management of semantic and behavioural problems in daily life. Caregivers of nfvPPA patients should be informed about the possible emergence of apraxia and other movement disorders. In contrast, families of individuals with lvPPA should be made aware of and trained to cope with an episodic memory decline and possible progression to other varieties of PPA.     

Our journey with primary progressive aphasia

Background: My husband Boyd and I had a 6-year journey with primary progressive aphasia (PPA) that held many challenges for us along the way. This article describes that journey.

Aims & Main Contribution: I hope that hearing about our experience may be helpful to other people with a family member who has PPA, and provide clinicians and researchers insight into the PPA journey.

Conclusions: I hope that through more research, there can be more understanding about PPA and consequently more support for families with members suffering this cruel disease.     

Electroencephalography in primary progressive aphasia and apraxia of speech

ABSTRACT

Background: Past research has demonstrated that electroencephalography (EEG) is sensitive to what we now know as Primary Progressive Aphasia (PPA); however, the EEG profiles of patients with Primary Progressive Apraxia of Speech (PPAOS) and PPA, in the context of current consensus criteria, have not been studied.

Aims: The primary goal of this study was to explore the EEG profiles of patients of the nonfluent/agrammatic variant of PPA (agPPA) and PPAOS.

Methods and Procedures: Three patients with agPPA and five patients with PPAOS (two with aphasia) completed a head MRI scan and clinical EEG recording. Clinical radiologists and electrophysiologists reviewed respective imaging, blinded to clinical diagnosis.

Outcomes and Results: Patients with PPAOS who did not have aphasia had normal EEGs, while those with aphasia demonstrated theta slowing. Patients with agPPA also showed theta slowing, with one exception. MRI scans showed non-specific, age-related changes across clinical presentations.

Conclusions: This preliminary study suggests theta slowing is consistent with neurodegenerative aphasia, but not isolated apraxia of speech. EEG is a low-cost mechanism to identify possible biomarkers for use when clinical severity limits behavioral examinations or expert examiners are unavailable.     

Functional disability in primary progressive aphasia

Background: In primary progressive aphasia (PPA), assessment of language predominates over assessment of functional impairment in activities of daily living (ADLs) in clinical and research environments. Most of the knowledge on functional disability in PPA relies largely on anecdotal experience and limited numbers of studies published to date.

Aims: (1) To describe the different patterns of ADL functional disability in the main PPA variants: semantic variant, nonfluent aphasia, and the more recently defined logopenic variant; (2) to draw relations between functional disability, cognitive, and behavioural symptoms in the PPAs; (3) to examine the impact of functional disability on carer burden, and (4) to provide specific strategies to address the described problems.

Main Contribution: Profiles of disease progression are described from a functional perspective, as well as the relationship (or lack thereof) between functional disability and cognitive and behavioural symptoms. Dementia-management strategies for carers and professionals in overcoming day-to-day difficulties are provided, and the impact of functional deficits on those around the patient, including their spouses and children, are discussed.

Conclusions: Patterns of ADL functional disability and their progression vary between PPA subtypes. Understanding these different profiles of impairment is critical to the development of tailored interventions. There is a range of therapeutic strategies which can be trialled to promote improved ADL functioning, which in turn may also help in reducing levels of carer burden in PPA.     

The genetics of primary progressive aphasia

Background: Primary progressive aphasia (PPA) is a disorder in which language impairment is the initial and predominant symptom. Three main phenotypes are described, the nonfluent variant (nfvPPA), the semantic variant (svPPA) and the logopenic variant (lvPPA). Although PPA is most commonly a sporadic disorder, recent studies have shown an association of PPA with mutations in a number of genes.

Aims: To understand the extent to which PPA may be inherited, which genetic mutations may cause it, and whether the phenotypes of genetic PPA differ from sporadic PPA.

Main Contribution: In around 20–30% of patients with PPA, a family history is present although nfvPPA is more heritable than svPPA and lvPPA which are both usually sporadic disorders. Mutations in the progranulin (GRN) and chromosome 9 open reading frame 72 (C9orf72), genes are the major causes of genetic PPA.

Conclusions: Key pointers that may suggest testing for a GRN mutation in PPA are a family history of one of the disorders within the frontotemporal dementia spectrum, a nfvPPA phenotype, particularly if presenting with a prominent anomia and asymmetrical fronto-temporo-parietal atrophy. In someone with nfvPPA and a family history, GRN should be tested initially but a search for hexanucleotide repeat expansions in the C9orf72 gene should be performed if negative, particularly if there are features of motor neurone disease, or a family history of someone with motor neurone disease. Mutations in other genes are only very rare causes of PPA but if GRN and C9orf72 are both negative, testing for mutations in the microtubule-associated protein tau (MAPT), valosin-containing protein (VCP) and presenilin 1 (PSEN1) should be considered.     

Relearning lost vocabulary in nonfluent progressive aphasia with MossTalk Words®

Background: The literature on aphasia has been growing rapidly, with reports of different therapeutic approaches for a post‐stroke anomia. While individuals with post‐stroke anomia frequently recover to some extent, the other end of the aphasia recovery continuum is occupied by those who experience relentless language dissolution as a result of progressive disorders such as primary progressive aphasia. One of the most recent additions to the field of aphasia rehabilitation is therapy whereby either part of or the entire therapy is administered via computer‐based programmes. There have been few treatment studies investigating the rehabilitation of language abilities in people with primary progressive aphasia (PPA).

Aims: The objectives of this investigation were to examine the ability of PPA individuals to relearn lost words and to determine the extent of benefits derived from MossTalk Words®, a computer‐based treatment for anomia.

Methods and Procedures: Using a multiple baseline across behaviours design, we explored treatment‐specific effects, maintenance, and generalisation of improvements derived from this therapy programme. Two participants with nonfluent PPA were treated, each on three lists of words for which low and stable baselines were first established. Sessions occurred two to three times a week. Treatment involved the presentation of a picture on the computer screen, with the participants being required to name it. Success in treatment was measured by probing list naming every second session. Once a participant attained 80% accuracy over two consecutive probes, or participated in 12 sessions (whichever occurred first), treatment of a list was terminated and the next list was started. Each participant was tested on all items immediately after therapy, and again 1 month later.

Outcomes and Results: Both participants improved their naming skills with the MossTalk Words®. P1 required only four sessions to reach the proposed criterion of 80% (up to 100%) correct on each list. The effects of treatment were maintained immediately and, to a lesser degree, 4 weeks later. P2 required all 12 sessions for each of the three lists. Results were variable immediately after testing, but seemingly maintained 4 weeks later.

Conclusions: The results demonstrate that both participants with primary progressive aphasia benefited (although to a different extent) from a computer‐based treatment for anomia. These results are encouraging and suggest that such a treatment may be a viable therapy approach for patients who suffer from PPA in the absence of a generalised cognitive impairment.     

Longitudinal study of single‐word comprehension in semantic dementia: A comparison with primary progressive aphasia and Alzheimer's disease

Background: Although semantic dementia (SD) is characterised by a multimodal loss of semantic knowledge, it has been demonstrated that lexical‐semantic representations are not equally disrupted in SD and that some categories may be recognised better than others. Little is known, however, about the pattern of the category‐specific comprehension deficits in SD and whether it differs from that of other forms of progressive aphasias.

Aims: This exploratory study aimed to investigate the evolution of category‐specific deficits of single‐word comprehension in progressive aphasias.

Methods & Procedures: A total of 19 patients with a clinical diagnosis of SD, 25 patients with primary progressive aphasia with agrammatic and relatively nonfluent speech (PPA), and 25 patients with Alzheimer's disease (AD) with aphasia were studied longitudinally with the Western Aphasia Battery (WAB). The Auditory Word Recognition subtest of the WAB was utilised to assess comprehension of words derived from different semantic categories.

Outcomes & Results: The analysis revealed that, over time, category‐specific deficits of single‐word comprehension were seen in all three groups of patients. Participants with SD as well as those with PPA and AD were impaired on both pointing to fingers and the right–left orientation task. However, patients with SD were the only group that showed defective recognition of their own body parts. Interestingly, individuals with SD had no difficulties identifying colours, letters, and numbers, even during the follow‐up testing. In addition, in all three groups the extent of category‐specific deficits was associated with the severity of aphasia.

Conclusions: These results indicate that category‐specific deficits of single‐word comprehension are frequently seen not only in patients with SD but also in individuals with PPA or AD, and that the extent of these deficits is associated with the severity of aphasia. However, the pattern of these deficits is often different in these three forms of neurodegenerative conditions and more dissociations between semantic categories are observed as each of these diseases progresses.     

Spontaneous verbal repetition: A social strategy in aphasic conversation

Abstract

This study investigated the spontaneous verbal repetition of a person with aphasia during conversation. Research questions were: Does repetition occur as a spontaneous verbal behaviour? How is repetion effectively used? What are the motivations for its use? A person with aphasia and his wife video recorded eight of their naturally occurring conversations which were subsequently transcribed and sequenced into turns-at-talk. Frequency of repetition and the sequential organization of conversation sequences containing repetition were analysed. Repetition was a frequent behaviour, occurring an average of 8% of the time for all conversations. Repetition was effectively used to meet the social needs of the conversation relating to displays of uncertainty, agreement, alignment and acknowledgement. Motivations for repetition related to its use as a compensatory strategy to overcome specific language barriers and to establish perceptions of conversational proficiency.     

The incidence of cases of aphasia following first stroke referred to speech and language therapy services in Scotland

Background: Key to the provision of appropriate services is an understanding of the number of cases in a given population. This study examined the incidence of aphasia following first ever stroke. It was part of a larger study, the Aphasia in Scotland Study, which examined the provision of services for people with aphasia in Scotland.

Aims: The present study examines the incidence of aphasia referred to speech and language therapy services in people who have experienced their first ever stroke. The specific questions addressed were: What is the incidence of aphasia following first ever stroke? What is the percentage of aphasia following first ever stroke? What are the crude figures for aphasia following first ever stroke by age? What are the crude figures for aphasia following first ever stroke by gender? What are the crude figures for aphasia following first ever stroke by severity?

Methods & Procedures: All 14 health boards in Scotland were approached but only 3, NHS Borders, Orkney, and Shetland, were able to provide the level of information required. Respondents were asked to provide information about the age and gender and level of communication need of referred cases over a given year.

Outcomes & Results: Results suggested that the incidence of aphasia following first ever stroke was found to be 54, 57, and 77.5 per 100,000, for NHS Borders, Orkney, and Shetland respectively. This is slightly higher than in other comparable studies. The percentage of new cases of aphasia following a first ever stroke across NHS Borders, Orkney, and Shetland was 19, 22, and 34% respectively. The variability across the three sites is probably a function of the potential effect of small changes in the relatively low numbers. The majority of cases were, unsurprisingly, over 65 years of age but a substantial minority—17% (Shetland), 26% (Borders) and 36% (Orkney)—were below 65 years of age. One third of new cases resulted in severe aphasia. Although the proportions of men and women with aphasia were similar, women tended to be older at the point at which they experienced their first stroke.

Conclusions: The results are discussed in terms the practicalities of this sort of data collection exercise and the implications of the results for service delivery. There is a need for comparable local data collection exercises tied in to current epidemiological studies.     

Multiple languages,memory, and regression: An examination of Ribot's Law

Background: Low-tech visual scene displays (VSDs) combine contextually rich pictures and written text to support the communication of people with aphasia. VSDs create a shared communication space in which a person with aphasia and a communication partner co-construct messages.

Aims: The researchers examined the effect of low-tech VSDs on the content and quality of communicative interactions between a person with aphasia and unfamiliar communication partners.

Methods &; Procedures: One person with aphasia and nine unfamiliar communication partners engaged in short, one-on-one conversations about a specified topic in one of three conditions: shared-VSDs, non-shared-VSDs, and no-VSDs. Data included discourse analysis scores reflecting the conceptual complexity of utterances, content unit analyses of information communication partners gathered from the interaction, and Likert-scale responses from the person with aphasia about his perception of communicative ease and effectiveness.

Outcomes &; Results: Comparisons made across conditions revealed: (a) the most conversational turns occurred in the shared-VSDs condition; (b) communication partners produced utterances with higher conceptual complexity in the shared-VSDs condition; (c) the person with aphasia conveyed the greatest number of content units in the shared-VSDs condition; and (d) the person with aphasia perceived that information transfer, ease of conversational interaction, and partner understanding were best in the shared-VSDs condition.

Conclusions: These findings suggest that low-tech VSDs have an impact on the manner and extent to which a person with aphasia and a communication partner contribute to conversational interactions involving information transfer.     

Dysgraphia in primary progressive aphasia: Characterisation of impairments and therapy options

Background: Spelling impairment is common in primary progressive aphasia (PPA). Although behavioural interventions tend to focus on spoken language, remediation of written language may be desirable, either because an individual’s regular use of writing makes it a priority or because writing is needed for communication in cases where it is better preserved than spoken language.

Aims: This paper has three aims: (1) to provide an up-to-date survey of spelling and handwriting impairments in each variant of PPA, (2) to provide guidance on characterisation of dysgraphia and identification of loci of impairment, and (3) to outline possible interventions. Because the number of studies which have specifically evaluated therapy for dysgraphia in PPA is small, this paper also reviews relevant studies of therapy in non-progressive dysgraphia.

Main Contribution: Review of the literature indicated that the most common pattern of spelling impairment in the semantic variant of PPA is surface dysgraphia (impairment in lexical spelling). The profile is more variable in the non-fluent and logopenic variants of PPA, but most commonly there is impairment in lexical spelling and in phoneme-to-grapheme conversion. Review of the literature on therapy for dysgraphia indicated that four main types of therapy have been evaluated and shown to improve spelling performance: (1) training of spelling of specific target words (used to ameliorate lexical and graphemic buffer impairments), (2) training of sound-to-spelling correspondence rules (used to treat impairment in assembled spelling), (3) training in segmentation of stimulus words into smaller chunks (to make them manageable for a damaged graphemic buffer, or as a first stage in applying sound-to-spelling correspondence rules), and (4) learning to identify and self-correct errors (used in treatment of graphemic buffer disorder).

Conclusions: It is likely that spelling impairment in PPA would be responsive to treatment, although this has only been demonstrated in the logopenic variant. Reported improvements following therapy for anomia demonstrate that relearning is possible in PPA, despite the progressive nature of the condition. This gives reason for optimism regarding a positive response to therapy for dysgraphia in all variants of PPA.     

Treating a semantic word production deficit in aphasia with verbal and gesture methods

Background: Classical aphasiology, based on the study of stroke sequelae, fuses speech fluency and grammatical ability. Nonfluent (Broca's) aphasia often is accompanied by agrammatism; whereas in the fluent aphasias grammatical deficits are not typical. The assumption that a similar relationship exists in primary progressive aphasia (PPA) has led to the dichotomisation of this syndrome into fluent and nonfluent subtypes.

Aims: This study compared elements of fluency and grammatical production in the narrative speech of individuals with PPA to determine if they can be dissociated from one another.

Methods &; Procedures: Speech samples from 37 individuals with PPA, clinically assigned to agrammatic (N?=?11), logopaenic (N?=?20), and semantic (N?=?6) subtypes, and 13 cognitively healthy control participants telling the “Cinderella Story” were analysed for fluency—i.e., words per minute (WPM) and mean length of utterance in words (MLU-W)—and grammaticality, i.e., the proportion of grammatically correct sentences, open-to-closed-class word ratio, noun-to-verb ratio, and correct production of verb inflection, noun morphology, and verb argument structure. Between-group differences were analysed for each variable. Correlational analyses examined the relation between WPM and each grammatical variable, and an off-line measure of sentence production.

Outcomes &; Results: Agrammatic and logopaenic groups both had lower scores on the fluency measures and produced significantly fewer grammatical sentences than did semantic and control groups. However, only the agrammatic group evinced significantly impaired production of verb inflection and verb argument structure. In addition some semantic participants showed abnormal open-to-closed and noun-to-verb ratios in narrative speech. When the sample was divided on the basis of fluency, all the agrammatic participants fell in the nonfluent category. The logopaenic participants varied in fluency but those with low fluency showed variable performance on measures of grammaticality. Correlational analyses and scatter plots comparing fluency and each grammatical variable revealed dissociations within PPA participants, with some nonfluent participants showing normal grammatical skill.

Conclusions: Grammatical production is a complex construct comprising correct usage of several language components, each of which can be selectively affected by disease. This study demonstrates that individuals with PPA show dissociations between fluency and grammatical production in narrative speech. Grammatical ability, and its relationship to fluency, varies from individual to individual, and from one variant of PPA to another, and can even be found in individuals with semantic PPA in whom a fluent aphasia is usually thought to accompany preserved ability to produce grammatical utterances.