The benefits and protective effects of behavioural treatment for dysgraphia in a case of primary progressive aphasia

Non-pharmacological interventions for improving language and communication in people with primary progressive aphasia

BACKGROUND

Primary progressive aphasia (PPA) accounts for approximately 43% of frontotemporal dementias and is mainly characterised by a progressive impairment of speech and communication abilities. Three clinical variants have been identified: (a) non-fluent/agrammatic, (b) semantic, and (c) logopenic/phonological PPA variants. There is currently no curative treatment for PPA, and the disease progresses inexorably over time, with devastating effects on speech and communication ability, functional status, and quality of life. Several non-pharmacological interventions that may improve symptoms (e.g. different forms of language training and non-invasive brain stimulation) have been investigated in people with PPA.

OBJECTIVES

To assess the effects of non-pharmacological interventions for people with PPA on word retrieval (our primary outcome), global language functions, cognition, quality of life, and adverse events.

SEARCH METHODS

We searched the Cochrane Dementia and Cognitive Improvement Group's trial register, MEDLINE (Ovid SP), Embase (Ovid SP), four other databases and two other trial registers. The latest searches were run on 26 January 2024.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) evaluating the effects of non-pharmacological interventions in people with PPA.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

There were insufficient data available to conduct the network meta-analyses that we had originally planned (due to trial data being insufficiently reported or not reported at all, as well as the heterogeneous content of the included interventions). Therefore, we provide a descriptive summary of the included studies and results. We included 10 studies, with a total of 132 participants, evaluating non-pharmacological interventions. These were: transcranial direct current stimulation (tDCS) or repetitive transcranial magnetic stimulation (rTMS) as stand-alone treatments (used by two and one studies, respectively); tDCS combined with semantic and phonological word-retrieval training (five studies); tDCS combined with semantic word-retrieval training (one study); and tDCS combined with phonological word-retrieval training (one study). Results for our primary outcome of word retrieval were mixed. For the two studies that investigated the effects of tDCS as stand-alone treatment compared to placebo ("sham") tDCS, we rated the results as having very low-certainty evidence. One study found a significant beneficial effect on word retrieval after active tDCS; one study did not report any significant effects in favour of the active tDCS group. Five studies investigated tDCS administered to the dorsolateral prefrontal cortex, inferior frontal cortex, left frontotemporal region, or the temporoparietal cortex, combined with semantic and phonological word-retrieval training. The most consistent finding was enhancement of word-retrieval ability for trained items immediately after the intervention, when behavioural training was combined with active tDCS compared to behavioural training plus sham tDCS. We found mixed effects for untrained items and maintenance of treatment effects during follow-up assessments. We rated the certainty of the evidence as very low in all studies. One study investigated tDCS combined with semantic word-retrieval training. Training was provided across 15 sessions with a frequency of three to five sessions per week, depending on the personal preferences of the participants. tDCS targeted the left frontotemporal region. The study included three participants: two received 1 mA stimulation and one received 2 mA stimulation. The study showed mixed results. We rated it as very low-certainty evidence. One study investigated tDCS combined with phonological word-retrieval training. Training was again provided across 15 sessions over a period of three weeks. tDCS targeted the left inferior frontal gyrus. This study showed a significantly more pronounced improvement for trained and untrained words in favour of the group that had received active tDCS, but we rated the certainty of the evidence as very low. One study compared active rTMS applied to an individually determined target site to active rTMS applied to a control site (vertex) for effects on participants' word retrieval. This study demonstrated better word retrieval for active rTMS administered to individually determined target brain regions than in the control intervention, but we rated the results as having a very low certainty of evidence. Four studies assessed overall language ability, three studies assessed cognition, five studies assessed potential adverse effects of brain stimulation, and one study investigated quality of life.

AUTHORS' CONCLUSIONS

There is currently no high-certainty evidence to inform clinical decision-making regarding non-pharmacological treatment selection for people with PPA. Preliminary evidence suggests that the combination of active tDCS with specific language therapy may improve impaired word retrieval for specifically trained items beyond the effects of behavioural treatment alone. However, more research is needed, including high-quality RCTs with detailed descriptions of participants and methods, and consideration of outcomes such as quality of life, depressive symptoms, and overall cognitive functioning. Moreover, studies assessing optimal treatments (i.e. behavioural interventions, brain stimulation interventions, and their combinations) for individual patients and PPA subtypes are needed. We were not able to conduct the planned (network) meta-analyses due to missing data that could not be obtained from most of the authors, a general lack of RCTs in the field, and heterogeneous interventions in eligible trials. Journals should implement a mandatory data-sharing requirement to assure transparency and accessibility of data from clinical trials.

Behavioral Treatment for Speech and Language in Primary Progressive Aphasia and Primary Progressive Apraxia of Speech: A Systematic Review

Primary progressive aphasia (PPA) and primary progressive apraxia of speech (PPAOS) are neurodegenerative syndromes characterized by progressive decline in language or speech. There is a growing number of studies investigating speech-language interventions for PPA/PPAOS. An updated systematic evaluation of the treatment evidence is warranted to inform best clinical practice and guide future treatment research. We systematically reviewed the evidence for behavioral treatment for speech and language in this population. Reviewed articles were published in peer-reviewed journals through 31 May 2021. We evaluated level of evidence, reporting quality, and risk of bias using a modified version of the American Speech-Language Hearing Association (ASHA) Levels of Evidence, an appraisal point system, additional reporting quality and internal/external validity items, and, as appropriate, the Single Case Experimental Design Scale or the Physiotherapy Evidence Database - PsycBITE Rating Scale for Randomized and Non-Randomized Controlled Trials. Results were synthesized using quantitative summaries and narrative review. A total of 103 studies reported treatment outcomes for 626 individuals with PPA; no studies used the diagnostic label PPAOS. Most studies evaluated interventions for word retrieval. The highest-quality evidence was provided by 45 experimental and quasi-experimental studies (16 controlled group studies, 29 single-subject designs). All (k = 45/45) reported improvement on a primary outcome measure; most reported generalization (k = 34/43), maintenance (k = 34/39), or social validity (k = 17/19) of treatment for at least one participant. The available evidence supports speech-language intervention for persons with PPA; however, treatment for PPAOS awaits systematic investigation. Implications and limitations of the evidence and the review are discussed.

Specificity in Generalization Effects of Transcranial Direct Current Stimulation Over the Left Inferior Frontal Gyrus in Primary Progressive Aphasia

OBJECTIVES

Generalization (or near-transfer) effects of an intervention to tasks not explicitly trained are the most desirable intervention outcomes. However, they are rarely reported and even more rarely explained. One hypothesis for generalization effects is that the tasks improved share the same brain function/computation with the intervention task. We tested this hypothesis in this study of transcranial direct current stimulation (tDCS) over the left inferior frontal gyrus (IFG) that is claimed to be involved in selective semantic retrieval of information from the temporal lobes.

MATERIALS AND METHODS

In this study, we examined whether tDCS over the left IFG in a group of patients with primary progressive aphasia (PPA), paired with a lexical/semantic retrieval intervention (oral and written naming), may specifically improve semantic fluency, a nontrained near-transfer task that relies on selective semantic retrieval, in patients with PPA.

RESULTS

Semantic fluency improved significantly more in the active tDCS than in the sham tDCS condition immediately after and two weeks after treatment. This improvement was marginally significant two months after treatment. We also found that the active tDCS effect was specific to tasks that require this IFG computation (selective semantic retrieval) but not to other tasks that may require different computations of the frontal lobes.

CONCLUSIONS

We provided interventional evidence that the left IFG is critical for selective semantic retrieval, and tDCS over the left IFG may have a near-transfer effect on tasks that depend on the same computation, even if they are not specifically trained.

CLINICAL TRIAL REGISTRATION

The Clinicaltrials.gov registration number for the study is NCT02606422.

Maintenance and Generalization of Lexical Items in Primary Progressive Aphasia: Reflections From the Roundtable Discussion at the 2021 Clinical Aphasiology Conference

PURPOSE

Our capacity to engage in society and maintain meaningful relationships is dependent on intact communication skills. They are compromised in a neurodegenerative language disorder termed primary progressive aphasia (PPA). Behavioral interventions for PPA are sparse and often limited to impairment-based approaches or communication skills training, although various functional interventions have been also described. The slow but relentless language decline does not naturally support maintenance and/or generalization of treatment gains, which should be the ultimate goal of any therapy. However, in some cases and under certain conditions, maintenance and generalization may be accomplished. While each type of intervention has much to offer to the PPA population, the clinical and research realms can benefit from a collective professional discussion on aspects of intervention conducive to maintenance and/or generalization of treatment gains in PPA. Such a discussion took place at the 2021 Clinical Aphasiology Conference during two roundtable sessions. The aims of the sessions were to review the premises of successful treatment approaches in PPA and to discuss factors fostering or inhibiting maintenance and generalization in PPA.

CONCLUSIONS

Current literature delivers, albeit in small doses, encouraging evidence for clinicians providing language intervention to patients with PPA. Although PPA is a progressive disorder, both the immediate treatment effects and, in many cases, evidence of maintenance and generalization demonstrate that improvements may be long lasting and transferrable. Several factors may enhance maintenance and generalization effects, including repeated practice, working with multiple exemplars of treatment items, booster sessions, group programs with built-in individual sessions, spared semantics, and personal relevance, to name a few. With this evidence in hand, we need to become more diligent about measuring and reporting clinical outcomes and delivering interventions that support maintenance and generalization of therapeutic gains beyond the clinician's office.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.19836370.

Sleep as a predictor of tDCS and language therapy outcomes

STUDY OBJECTIVES

To determine whether sleep at baseline (before therapy) predicted improvements in language following either language therapy alone or coupled with transcranial direct current stimulation (tDCS) in individuals with primary progressive aphasia (PPA).

METHODS

Twenty-three participants with PPA (mean age 68.13 ± 6.21) received written naming/spelling therapy coupled with either anodal tDCS over the left inferior frontal gyrus (IFG) or sham condition in a crossover, sham-controlled, double-blind design (ClinicalTrials.gov identifier: NCT02606422). The outcome measure was percent of letters spelled correctly for trained and untrained words retrieved in a naming/spelling task. Given its particular importance as a sleep parameter in older adults, we calculated sleep efficiency (total sleep time/time in bed x100) based on subjective responses on the Pittsburgh Sleep Quality Index (PSQI). We grouped individuals based on a median split: high versus low sleep efficiency.

RESULTS

Participants with high sleep efficiency benefited more from written naming/spelling therapy than participants with low sleep efficiency in learning therapy materials (trained words). There was no effect of sleep efficiency in generalization of therapy materials to untrained words. Among participants with high sleep efficiency, those who received tDCS benefitted more from therapy than those who received sham condition. There was no additional benefit from tDCS in participants with low sleep efficiency.

CONCLUSION

Sleep efficiency modified the effects of language therapy and tDCS on language in participants with PPA. These results suggest sleep is a determinant of neuromodulation effects.Clinical Trial: tDCS Intervention in Primary Progressive Aphasia https://clinicaltrials.gov/ct2/show/NCT02606422.

Behavioral interventions for primary progressive aphasia

Primary progressive aphasia (PPA) is a neurodegenerative syndrome characterized by a gradual loss of communication ability. Due to the centrality of communication deficits, speech-language pathologists play a prominent role in the provision of care for individuals with PPA. In this chapter, we outline a person-centered approach to the management of PPA that aims to preserve independence for as long as possible while anticipating future decline in communication and other domains. A growing evidence base supports the utility of speech-language treatment approaches in PPA, including restitutive, compensatory, and communication partner-focused techniques. Restitutive interventions aim to rebuild lost communication skills, such as naming or fluent speech production. Compensatory approaches include training with high- and low-tech augmentative and alternative communication systems that provide complementary means of communication beyond speech. Communication partner interventions focus on education and strategy training in order to equip conversation partners as skilled communication facilitators. Throughout intervention, clinicians should aim to provide treatment that impacts functional communication and promotes social engagement. Given the documented benefits of speech-language intervention in PPA, we are optimistic that such treatment will become the standard of care and that additional research will continue to improve the quality and accessibility of behavioral interventions.

A Systematic Review of Transcranial Direct Current Stimulation in Primary Progressive Aphasia: Methodological Considerations

A variety of tDCS approaches has been used to investigate the potential of tDCS to improve language outcomes, or slow down the decay of language competences caused by Primary Progressive Aphasia (PPA). The employed stimulation protocols and study designs in PPA are generally speaking similar to those deployed in post-stroke aphasic populations. These two etiologies of aphasia however differ substantially in their pathophysiology, and for both conditions the optimal stimulation paradigm still needs to be established. A systematic review was done and after applying inclusion and exclusion criteria, 15 articles were analyzed focusing on differences and similarities across studies especially focusing on PPA patient characteristics (age, PPA variant, language background), tDCS stimulation protocols (intensity, frequency, combined therapy, electrode configuration) and study design as recent reviews and group outcomes for individual studies suggest tDCS is an effective tool to improve language outcomes, while methodological approach and patient characteristics are mentioned as moderators that may influence treatment effects. We found that studies of tDCS in PPA have clinical and methodological and heterogeneity regarding patient populations, stimulation protocols and study design. While positive group results are usually found irrespective of these differences, the magnitude, duration and generalization of these outcomes differ when comparing stimulation locations, and when results are stratified according to the clinical variant of PPA. We interpret the results of included studies in light of patient characteristics and methodological decisions. Further, we highlight the role neuroimaging can play in study protocols and interpreting results and make recommendations for future work.

Cognitive Intervention Strategies Directed to Speech and Language Deficits in Primary Progressive Aphasia: Practice-Based Evidence from 18 Cases

BACKGROUND

Practice-based evidence can inform and support clinical decision making. Case-report series about the implementation of programs in real-world clinical settings may contribute to verifying the effectiveness of interventions for treating PPA in specific contexts, as well as illustrating challenges that need to be overcome.

OBJECTIVE

To describe and provide practice-based evidence on the effectiveness of four cognitive rehabilitation programs designed for individuals with PPA and directed to speech and language impairments, which were implemented in a specialized outpatient clinic.

METHODS

Multiple single-case study. Eighteen individuals with different subtypes of PPA were each assigned to one out of four training programs based on comprehensive speech and language assessments. The treatments targeted naming deficits, sentence production, speech apraxia, and phonological deficits. Pre- and post-treatment assessments were undertaken to compare trained and untrained items. Gains were generalized to a different task in the first two types of intervention (naming and sentence production). A follow-up assessment was conducted 1-8 months after treatment among 7 participants.

RESULTS

All individuals presented better performance in the trained items at the post-test for each rehabilitation program accomplished, demonstrating that learning of the trained strategies was achieved during the active phase of treatment. For 13 individuals, statistical significance was reached; while for five, the results were maintained. Results about untrained items, generalization to other tasks, and follow-up assessments are presented.

CONCLUSIONS

The positive results found in our sample bring some practice-based evidence for the benefits of speech and language treatment strategies for clinical management of individuals with PPA.

Language training for oral and written naming impairment in primary progressive aphasia: a review

BACKGROUND

Primary progressive aphasia (PPA) is a neurodegenerative disorder characterized by a gradual, insidious and progressive loss of language abilities, with naming difficulties being an early and persistent impairment common to all three variants. In the absence of effective pharmacological treatments and given the progressive nature of the disorder, in the past few decades, many studies have investigated the effectiveness of language training to minimize the functional impact of word-finding difficulties in daily life.

MAIN BODY

We review language treatments most commonly used in clinical practice among patients with different variants of PPA, with a focus on the enhancement of spoken and written naming abilities. Generalization of gains to the ability to name untrained stimuli or to other language abilities and the maintenance of these results over time are also discussed. Forty-eight studies were included in this literature review, identifying four main types of language treatment: a) lexical retrieval treatment, b) phonological and/or orthographic treatment, c) semantic treatment, and d) a multimodality approach treatment. Overall, language training is able to induce immediate improvements of naming abilities in all variants of PPA. Moreover, despite the large variability among results, generalization and long-term effects can be recorded after the training. The reviewed studies also suggest that one factor that determines the choice of a particular approach is the compromised components of the lexical/semantic processing system.

CONCLUSION

The majority of studies have demonstrated improvements of naming abilities following language treatments. Given the progressive nature of PPA, it is essential to apply language treatment in the early stages of the disease.

Selective Functional Network Changes Following tDCS-Augmented Language Treatment in Primary Progressive Aphasia

Objective

Transcranial direct current stimulation (tDCS) has shown promising results when used as an adjunct to behavioral training in neurodegenerative diseases. However, the underlying neural mechanisms are not understood and neuroimaging evidence from pre/post treatment has been sparse. In this study, we examined tDCS-induced neural changes in a language intervention study for primary progressive aphasia (PPA), a neurodegenerative syndrome with language impairment as the primary clinical presentation. Anodal tDCS was applied to the left inferior frontal gyrus (LIFG). To evaluate the hypothesis that tDCS promotes system segregation, analysis focused on understanding tDCS-induced changes in the brain-wide functional network connectivity of the targeted LIFG.

Methods

Resting-state fMRI data were obtained from 32 participants with PPA before and after receiving a written naming therapy, accompanied either by tDCS or sham stimulation. We focused on evaluating changes in the global connectivity of the stimulated LIFG-triangularis (LIFG-tri) region given its important role in lexical processing. Global connectivity was indexed by the graph-theoretic measure participation coefficient (PC) which quantifies a region’s level of system segregation. The values before and after treatment were compared for each condition (tDCS or Sham) as well as with age-matched healthy controls (n = 19).

Results

Higher global connectivity of the LIFG-tri before treatment was associated with greater dementia severity. After treatment, the tDCS group showed a significant decrease in global connectivity whereas the Sham group’s did not change, suggesting specific neural effects induced by tDCS. Further examination revealed that the decrease was driven by reduced connectivity between the LIFG-tri and regions outside the perisylvian language area, consistent with the hypothesis that tDCS enhances the segregation of the language system and improves processing efficiency. Additionally, we found that these effects were specific to the LIFG-tri and not observed in other control regions.

Conclusion

TDCS-augmented language therapy in PPA increased the functional segregation of the language system, a normalization of the hyper-connectivity observed before treatment. These findings add to our understanding of the nature of tDCS-induced neural changes in disease treatment and have applications for validating treatment efficacy and designing future tDCS and other non-invasive brain stimulation (NIBS) treatments.

White Matter Integrity Predicts Electrical Stimulation (tDCS) and Language Therapy Effects in Primary Progressive Aphasia

BACKGROUND

Transcranial direct current stimulation (tDCS), in conjunction with language therapy, improves language therapy outcomes in primary progressive aphasia (PPA). However, no studies show whether white matter integrity predicts language therapy or tDCS effects in PPA.

OBJECTIVE

We aimed to determine whether white matter integrity, measured by diffusion tensor imaging (DTI), predicts written naming/spelling language therapy effects (letter accuracy on trained and untrained words) with and without tDCS over the left inferior frontal gyrus (IFG) in PPA.

METHODS

Thirty-nine participants with PPA were randomly assigned to tDCS or sham condition, coupled with language therapy for 15 daily sessions. White matter integrity was measured by mean diffusivity (MD) and fractional anisotropy (FA) in DTI scans before therapy. Written naming outcomes were evaluated before, immediately after, 2 weeks, and 2 months posttherapy. To assess tDCS treatment effect, we used a mixed-effects model with treatment evaluation and time interaction. We considered a forward model selection approach to identify brain regions/fasciculi of which white matter integrity can predict improvement in performance of word naming.

RESULTS

Both sham and tDCS groups significantly improved in trained items immediately after and at 2 months posttherapy. Improvement in the tDCS group was greater and generalized to untrained words. White matter integrity of ventral language pathways predicted tDCS effects in trained items whereas white matter integrity of dorsal language pathways predicted tDCS effects in untrained items.

CONCLUSIONS

White matter integrity influences both language therapy and tDCS effects. Thus, it holds promise as a biomarker for deciding which patients will benefit from language therapy and tDCS.

How Evidence-Based Practice (E3BP) Informs Speech-Language Pathology for Primary Progressive Aphasia

Amelioration of communication impairment in primary progressive aphasia (PPA) is an area of clinical importance and current research. Speech-language pathologists (SLPs) have a range of skills and interventions to support communication in PPA; however, underrecognition of their role and low referral rates is an ongoing concern. The E3BP conceptualization of evidence-based practice comprises 3 components: research-based evidence, practice-based evidence, and informed patient preferences. Here, we will describe how evidence for managing the communication difficulties experienced by individuals with PPA exists at all 3 levels of the (E3BP) model, highlighting how this allows SLP interventions to be both evidence based and patient centered. We encourage health professionals to value and utilize the wide range of services that SLPs can offer when working with individuals with PPA, to educate, remediate everyday linguistic skills, increase daily participation, and maximize overall quality of life.

Brain volumes as predictors of tDCS effects in primary progressive aphasia

The current study aims to determine the brain areas critical for response to anodal transcranial direct current stimulation (tDCS) in PPA. Anodal tDCS and sham were administered over the left inferior frontal gyrus (IFG), combined with written naming/spelling therapy. Thirty people with PPA were included in this study, and assessed immediately, 2 weeks, and 2 months post-therapy. We identified anatomical areas whose volumes significantly predicted the additional tDCS effects. For trained words, the volumes of the left Angular Gyrus and left Posterior Cingulate Cortex predicted the additional tDCS gain. For untrained words, the volumes of the left Middle Frontal Gyrus, left Supramarginal Gyrus, and right Posterior Cingulate Cortex predicted the additional tDCS gain. These findings show that areas involved in language, attention and working memory contribute to the maintenance and generalization of stimulation effects. The findings highlight that tDCS possibly affects areas anatomically or functionally connected to stimulation targets.

Cognitive and language performance predicts effects of spelling intervention and tDCS in Primary Progressive Aphasia

Predictors of treatment effects allow individual tailoring of treatment characteristics, thereby saving resources and optimizing outcomes. Electrical stimulation coupled with language intervention has shown promising results in improving language performance in individuals with Primary Progressive Aphasia (PPA). The current study aimed to identify language and cognitive variables associated with response to therapy consisting of language intervention combined with transcranial direct current stimulation (tDCS). Forty individuals with PPA received written naming/spelling intervention combined with anodal tDCS or Sham, using a between-subjects, randomized design, with intervention delivered over a period of 3 weeks. Participants were assessed using a battery of neuropsychological tests before and after each phase. We measured letter accuracy during spelling of trained and untrained words, before, immediately after, 2 weeks, and 2 months after therapy. We used step-wise regression methods to identify variables amongst the neuropsychological measures and experimental factors that were significantly associated with therapy outcomes at each time-point. For trained words, improvement was related to pre-therapy scores, in RAVLT (5 trials sum), pseudoword spelling, object naming, digit span backward, spatial span backward and years post symptom onset. Regarding generalization to untrained words, improvement in spelling was associated with pseudoword spelling, RAVLT proactive interference, RAVLT immediate recall. Generalization effects were larger under tDCS compared to Sham at the 2-month post training measurement. We conclude that, for trained words, patients who improve the most are those who retain for longer language skills such as sublexical spelling processes (phoneme-to-grapheme correspondences) and word retrieval, and other cognitive functions such as executive functions and working memory, and those who have a better learning capacity. Generalization to untrained words occurs through improvement in knowledge of phoneme-to-grapheme correspondences. Furthermore, tDCS enhances the generalizability and duration of therapy effects.

Written Verb Naming Improves After tDCS Over the Left IFG in Primary Progressive Aphasia

Transcranial direct current stimulation (tDCS), a non-invasive neuromodulation technique, is an effective adjunct to naming treatments in post-stroke aphasia and primary progressive aphasia (PPA). Enhanced performance in oral and written naming and spelling of nouns with tDCS has been quantified in detail, but it is not known whether it is effective for verb treatment in PPA. We addressed the question of whether performance in naming and spelling of verbs can be augmented with anodal tDCS over the left inferior frontal gyrus (IFG). We compared tDCS coupled with oral and written verb naming/spelling treatment with oral and written verb naming/spelling treatment alone. In a double-blind, sham-controlled, crossover design, 11 participants with logopenic or non-fluent variant PPA received approximately 15 consecutive sessions of anodal tDCS and sham over the left IFG coupled with oral and written verb-naming + spelling treatment. Written verb-naming performance improved significantly more for trained verbs in the tDCS than the sham condition. Importantly, tDCS effects generalized to untrained items for written verb naming and were significant even at 2 months post-treatment. We conclude that tDCS over the left IFG can improve written verb naming and spelling in PPA.

Reductions in GABA following a tDCS-language intervention for primary progressive aphasia

Transcranial direct current stimulation (tDCS) has shown efficacy in augmenting the effects of language therapy in primary progressive aphasia (PPA). The mechanism of action of tDCS is not understood, but preliminary work in healthy adults suggests it modulates γ-aminobutyric acid (GABA) levels to create an environment optimal for learning. It is unknown if this proposed mechanism translates to aging or neurodegenerative conditions. This study tested the hypothesis that tDCS reduces GABA at the stimulated tissue in PPA. We applied GABA-edited magnetic resonance spectroscopy to quantify GABA levels before and after a sham-controlled tDCS intervention with language therapy in PPA. All participants showed improvements but those receiving active tDCS showed significantly greater language improvements compared to sham both immediately after the intervention and at 2-month follow-up. GABA levels in the targeted tissue decreased from baseline after the intervention and remained decreased 2 months after the intervention. This work supports the hypothesis that tDCS modulates GABAergic inhibition to augment learning and is clinically useful for PPA combined with language therapy.

"The effect of tDCS on functional connectivity in primary progressive aphasia" NeuroImage: Clinical, volume 19 (2018), pages 703-715

Transcranial direct current stimulation (tDCS) is an innovative technique recently shown to improve language outcomes even in neurodegenerative conditions such as primary progressive aphasia (PPA), but the underlying brain mechanisms are not known. The present study tested whether the additional language gains with repetitive tDCS (over sham) in PPA are caused by changes in functional connectivity between the stimulated area (the left inferior frontal gyrus (IFG)) and the rest of the language network. We scanned 24 PPA participants (11 female) before and after language intervention (written naming/spelling) with a resting-state fMRI sequence and compared changes before and after three weeks of tDCS or sham coupled with language therapy. We correlated changes in the language network as well as in the default mode network (DMN) with language therapy outcome measures (letter accuracy in written naming). Significant tDCS effects in functional connectivity were observed between the stimulated area and other language network areas and between the language network and the DMN. TDCS over the left IFG lowered the connectivity between the above pairs. Changes in functional connectivity correlated with improvement in language scores (letter accuracy as a proxy for written naming) evaluated before and after therapy. These results suggest that one mechanism for anodal tDCS over the left IFG in PPA is a decrease in functional connectivity (compared to sham) between the stimulated site and other posterior areas of the language network. These results are in line with similar decreases in connectivity observed after tDCS over the left IFG in aging and other neurodegenerative conditions.

Treatment for spoken and written word retrieval in the semantic variant of primary progressive aphasia

This study investigated whether a treatment programme for spoken word retrieval, supplemented with written naming, was beneficial for an individual with right-hemisphere dominant semantic variant of PPA (svPPA). Assessment and treatment were delivered remotely through Skype. Treatment consisted of two phases of lexical retrieval therapy (Repetition and Reading in the Presence of a Picture: RRIPP), with and without written responses (Phases 1 and 2 respectively), and a third treatment phase based on the procedures of Conceptual Enrichment (COEN) therapy. The first two phases of treatment resulted in short-lasting improvements in spoken and written word retrieval, with greater improvement in Phase 2 when written production was also required. Both treatment phases resulted in gains only for treated items, but generalised to different depictions to those treated. However, Phase 2 also resulted in significant improvement of treated items on a comprehension task. COEN treatment did not result in significant gains in word retrieval or comprehension. This study reinforces the value of a simple lexical retrieval treatment delivered remotely. It adds to the current evidence that anomia in svPPA can be responsive to treatment, but also shows that challenges remain regarding maintenance effects and the generalisation of treatment effects to connected speech.

Electrical brain stimulation in different variants of primary progressive aphasia: A randomized clinical trial

Introduction

Transcranial direct current stimulation (tDCS) has been recently shown to improve language outcomes in primary progressive aphasia (PPA) but most studies are small and the influence of PPA variant is unknown.

Methods

Thirty-six patients with PPA participated in a randomized, sham-controlled, double-blind, within-subject crossover design for 15 daily sessions of stimulation coupled with written naming/spelling therapy. Outcome measures were letter accuracy of treated and untreated words immediately after and at 2 weeks and 2 months posttreatment.

Results

tDCS treatment was more effective than sham: gains for treated words were maintained 2 months posttreatment; gains from tDCS also generalized to untreated words and were sustained 2 months posttreatment. Different effects were obtained for each PPA variant, with no tDCS advantage for semantic variant PPA.

Discussion

The study supports using tDCS as an adjunct to written language interventions in individuals with logopenic or nonfluent/agrammatic PPA seeking compensatory treatments in clinical settings.

The effect of tDCS on functional connectivity in primary progressive aphasia

Transcranial direct current stimulation (tDCS) is an innovative technique recently shown to improve language outcomes even in neurodegenerative conditions such as primary progressive aphasia (PPA), but the underlying brain mechanisms are not known. The present study tested whether the additional language gains with repetitive tDCS (over sham) in PPA are caused by changes in functional connectivity between the stimulated area (the left inferior frontal gyrus (IFG)) and the rest of the language network. We scanned 24 PPA participants (11 female) before and after language intervention (written naming/spelling) with a resting-state fMRI sequence and compared changes before and after three weeks of tDCS or sham coupled with language therapy. We correlated changes in the language network as well as in the default mode network (DMN) with language therapy outcome measures (letter accuracy in written naming). Significant tDCS effects in functional connectivity were observed between the stimulated area and other language network areas and between the language network and the DMN. TDCS over the left IFG lowered the connectivity between the above pairs. Changes in functional connectivity correlated with improvement in language scores (letter accuracy as a proxy for written naming) evaluated before and after therapy. These results suggest that one mechanism for anodal tDCS over the left IFG in PPA is a decrease in functional connectivity (compared to sham) between the stimulated site and other posterior areas of the language network. These results are in line with similar decreases in connectivity observed after tDCS over the left IFG in aging and other neurodegenerative conditions.

The effect of tDCS on functional connectivity in primary progressive aphasia

Transcranial direct current stimulation (tDCS) is an innovative technique recently shown to improve language outcomes even in neurodegenerative conditions such as primary progressive aphasia (PPA), but the underlying brain mechanisms are not known. The present study tested whether the additional language gains with repetitive tDCS (over sham) in PPA are caused by changes in functional connectivity between the stimulated area (the left inferior frontal gyrus (IFG)) and the rest of the language network. We scanned 24 PPA participants (11 female) before and after language intervention (written naming/spelling) with a resting-state fMRI sequence and compared changes before and after three weeks of tDCS or sham coupled with language therapy. We correlated changes in the language network as well as in the default mode network (DMN) with language therapy outcome measures (letter accuracy in written naming). Significant tDCS effects in functional connectivity were observed between the stimulated area and other language network areas and between the language network and the DMN. TDCS over the left IFG lowered the connectivity between the above pairs. Changes in functional connectivity correlated with improvement in language scores (letter accuracy as a proxy for written naming) evaluated before and after therapy. These results suggest that one mechanism for anodal tDCS over the left IFG in PPA is a decrease in functional connectivity (compared to sham) between the stimulated site and other posterior areas of the language network. These results are in line with similar decreases in connectivity observed after tDCS over the left IFG in aging and other neurodegenerative conditions.

Transcranial direct current stimulation in post stroke aphasia and primary progressive aphasia: Current knowledge and future clinical applications

BACKGROUND

The application of transcranial direct current stimulation (tDCS) in chronic post stroke aphasia is documented in a substantial literature, and there is some new evidence that tDCS can augment favorable language outcomes in primary progressive aphasia. Anodal tDCS is most often applied to the left hemisphere language areas to increase cortical excitability (increase the threshold of activation) and cathodal tDCS is most often applied to the right hemisphere homotopic areas to inhibit over activation in contralesional right homologues of language areas. Outcomes usually are based on neuropsychological and language test performance, following a medical model which emphasizes impairment of function, rather than a model which emphasizes functional communication.

OBJECTIVE

In this paper, we review current literature of tDCS as it is being used as a research tool, and discuss future implementation of tDCS as an adjuvant treatment to behavioral speech-language pathology intervention.

METHODS

We review literature describing non-invasive brain stimulation, the mechanism of tDCS, and studies of tDCS in aphasia and neurodegenerative disorders. We discuss future clinical applications.

RESULTS/CONCLUSIONS

tDCS is a promising adjunct to traditional speech-language pathology intervention to address speech-language deficits after stroke and in the neurodegenerative disease, primary progressive aphasia. Limited data are available regarding how performance on these types of specific tasks translates to functional communication outcomes.

Group intervention for individuals with primary progressive aphasia and their spouses: Who comes first?

Primary progressive aphasia (PPA) is a neurodegenerative dementia in which language impairment is the first and most dominant symptom. There is a considerable dearth of interventions for PPA although language rehabilitation has made headway in managing the disorder. Thus far, no comprehensive services have been proposed for PPA clients and/or their spouses. This paper describes the first structured group intervention program designated exclusively for people with PPA and their caregivers. This pilot project originates from a clinical service and presents supporting evidence for initiation of a larger study to establish an evidence-based intervention for PPA. A 10-week intervention program comprised working on language activities, learning communication strategies, counselling and education. Outcome measures administered to participants and their spouses before and after the intervention were compared showed improvements in quality of communication and coping skills in the PPA group compared to controls. Qualitative comments from all 10 participants in the active treatment group highlighted the necessity of intervention that is tailored specifically to the PPA population and addresses the needs of both individuals with PPA and their caregivers. All participants in the intervention group contributed to the study and are also co-authors of this paper.

Communication Bridge: A pilot feasibility study of Internet-based speech-language therapy for individuals with progressive aphasia

Introduction

Individuals with aphasia symptoms due to neurodegenerative disease are under-referred for speech–language therapy (SLT) services. We sought to determine the feasibility of utilizing telepractice, via Internet videoconferencing, to connect individuals with progressive aphasia to a speech–language pathologist (SLP) for treatment.

Methods

Participants received an initial evaluation, 8 person-centered Internet-based SLT sessions, and 2 post-therapy evaluations. The feasibility of providing Web-based SLT, strategies used and their compliance, functional gains, and the duration of benefit were assessed.

Results

Thirty-four participants from 21 states and Canada were enrolled. Thirty-one participants completed the 6-month evaluation. SLP-assessed and self-reported functional gains and increased confidence in communication were documented at 2 months and maintained at 6 months postenrollment.

Discussion

Internet-based SLT using person-centered interventions provides a feasible model for delivering care to individuals with dementia and mild and/or moderate aphasia symptoms who have an engaged care-partner and prior familiarity with a computer.

Exploring generalisation processes following lexical retrieval intervention in primary progressive aphasia

PURPOSE

Within the current literature, positive intervention effects demonstrate the significant potential for people with Primary Progressive Aphasia (PPA) to learn/relearn words. Generalisation of intervention effects to other words and/or other contexts, however, remains unclear.

METHOD

This multiple baseline, case-series design investigated the effects of a self-cueing lexical retrieval intervention across word classes (nouns, verbs and adjectives) on four individuals with PPA, three suggestive of the semantic variant and one of the logopenic variant. The intervention integrated semantic, phonological and orthographic levels of language production and drew on autobiographical memory. Changes in accuracy in retrieving treated and untreated items (pre-intervention, post-intervention and 4-weeks maintenance) were determined using the Cochran's Q test, with follow-up McNemar pairwise comparisons.

RESULT

All participants showed significant improvements in naming treated items, across all word classes. Different patterns of generalised improvement to untreated words were found for each participant. In discourse, the semantic variant participants demonstrated a significant increase in correct information units, in contrast to the participant with the logopenic variant who remained stable.

CONCLUSION

This study provides evidence that people with PPA can show improved lexical retrieval following intervention. The findings suggest possible differences in generalisation across word classes and according to underlying deficit.

Positive impact of speech therapy in progressive non-fluent aphasia

The aim of this paper is to analyze the effects of intensive speech therapy intervention in a case of progressive non-fluent aphasia (PNFA). This is a dementia syndrome characterized by a progressive deficit in expressive language fluency and syntactic analysis, and by agrammatism and phonemic paraphasias. Although in the early stages there are no alterations in memory, comprehension, or visual processing, personality changes can slightly occur. To analyze the effects of speech therapy in this syndrome, a single case design with pre- and post-test was used. The participant was a male patient of 84 years with PNFA, who for twelve months received weekly speech therapy to stimulate the phonological, lexical and syntactic processing. He underwent neuropsychological assessment in three stages: six months before the onset of therapy, six months after therapy started and after completing 12 months of intervention. Assessment involved linguistic processing, general cognition, neuropsychiatric symptoms, quality of life (QOL) and activities of daily living (ADL). As a result of therapy, the patient showed a slight improvement in language prosody, fluency, and content of spontaneous speech, and a significant improvement in repetition, reading aloud, and oral-phonatory praxis. Other aspects of cognitive functioning (orientation, verbal naming, praxis, and memory) remained stable; ADLs and QoL improved. It is concluded that prolonged speech therapy can improve language processing and have a positive impact on other cognitive and socio-emotional processes in PNFA. This 12-month therapeutic stimulation not only slowed cognitive decline, but allowed to see maintenance of achievements and improvement of symptoms, which can be regarded as a success in PNFA treatment, considering the rapid progression of the disease.

Is descriptive writing useful in the differential diagnosis of logopenic variant of primary progressive aphasia, Alzheimer's disease and mild cognitive impairment?

Current classification of primary progressive aphasia (PPA) encompasses three variants: non-fluent (nfvPPA), semantic (svPPA) and logopenic (lvPPA). Previously lvPPA was regarded as aphasic form of Alzheimer's disease (AD). However, not all patients with lvPPA phenotype present with AD pathology. Despite abundant literature on differentiation of lvPPA from svPPA and nfvPPA, studies comparing lvPPA with AD and mild cognitive impairment (MCI) are scarce. This study aimed at analyzing written descriptive output in lvPPA, AD and MCI. Thirty-five patients participated in the study: 9 with lvPPA, 13 with AD and 13 with MCI. Most aspects of writing performance were comparable in three groups. However, letter insertion errors appeared in 44% patients with lvPPA, while they were absent in AD and MCI. Patients with lvPPA used more verbs than patients with AD. Writing profile may complement other neuropsychological assessment results in the differential diagnosis of lvPPA. Letter insertion errors and frequent verb use may raise a query of lvPPA.

Treatment of Primary Progressive Aphasia

OPINION STATEMENT

Primary progressive aphasia (PPA) is a neurodegenerative disease that primarily affects language functions and often begins in the fifth or sixth decade of life. The devastating effects on work and home life call for the investigation of treatment alternatives. In this paper, we present a review of the literature on treatment approaches for this neurodegenerative disease. We also present new data from two intervention studies we have conducted, a behavioral one and a neuromodulatory one using transcranial direct current stimulation (tDCS) combined with written production intervention. We show that speech-language intervention improves language outcomes in individuals with PPA, and especially in the short term, tDCS augments generalization and maintenance of positive language outcomes. We also outline current issues and challenges in intervention approaches in PPA.

Generalisation after treatment of acquired spelling impairments: A review

This paper provides a comprehensive review of treatment studies of acquired dysgraphia and the occurrence of generalisation after this treatment. The aim is to examine what determines the occurrence of generalisation by investigating the link between the level of impairment, the method of treatment, and the outcome of therapy. We present the outcomes of treatment with regard to generalisation in 40 treatment studies. We derive general principles of generalisation which provide us with a better understanding of the mechanism of generalisation: (1) Direct treatment effects on representations or processes; (2) interactive processing and summation of activation; and (3) strategies and compensatory skills. We discuss the implications of these findings for our understanding of the cognitive processes used for spelling. Finally, we provide suggestions for the direction of further research into this important area, as a better understanding of the mechanism of generalisation could maximise treatment effects for an individual with acquired dysgraphia.

Augmentation of spelling therapy with transcranial direct current stimulation in primary progressive aphasia: Preliminary results and challenges

BACKGROUND

Primary progressive aphasia (PPA) is a neurodegenerative disease that primarily affects language functions and often begins in the fifth or sixth decade of life. The devastating effects on work and family life call for the investigation of treatment alternatives. In this article, we present new data indicating that neuromodulatory treatment, using transcranial direct current stimulation (tDCS) combined with a spelling intervention, shows some promise for maintaining or even improving language, at least temporarily, in PPA.

AIMS

The main aim of the present article is to determine whether tDCS plus spelling intervention is more effective than spelling intervention alone in treating written language in PPA. We also asked whether the effects of tDCS are sustained longer than the effects of spelling intervention alone.

METHODS & PROCEDURES

We present data from six PPA participants who underwent anodal tDCS or sham plus spelling intervention in a within-subject crossover design. Each stimulation condition lasted 3 weeks or a total of 15 sessions with a 2-month interval in between. Participants were evaluated on treatment tasks as well as on other language and cognitive tasks at 2-week and 2-month follow-up intervals after each stimulation condition.

OUTCOMES & RESULTS

All participants showed improvement in spelling (with sham or tDCS). There was no difference in the treated items between the two conditions. There was, however, consistent and significant improvement for untrained items only in the tDCS plus spelling intervention condition. Furthermore, the improvement lasted longer in the tDCS plus spelling intervention condition compared to sham plus spelling intervention condition.

CONCLUSIONS

Neuromodulation with tDCS offers promise as a means of augmenting language therapy to improve written language function at least temporarily in PPA. The consistent finding of generalisation of treatment benefits to untreated items and the superior sustainability of treatment effects with tDCS justifies further investigations. However, the small sample size still requires caution in interpretation. Present interventions need to be optimised, and particular challenges, such as ways to account for the variable effect of degeneration in each individual, are discussed.

Treatment for apraxia of speech in nonfluent variant primary progressive aphasia

There is a growing body of literature examining the utility of behavioral treatment in primary progressive aphasia (PPA). There are, however, no studies exploring treatment approaches to improve speech production in individuals with apraxia of speech (AOS) associated with the nonfluent variant of PPA. The purpose of this study was to examine a novel approach to treatment of AOS in nonfluent PPA. We implemented a treatment method using structured oral reading as a tool for improving production of multisyllabic words in an individual with mild AOS and nonfluent variant PPA. Our participant showed a reduction in speech errors during reading of novel text that was maintained at one year post-treatment. Generalization of improved speech production was observed on repetition of words and sentences and the participant showed stability of speech production over time in connected speech. Results suggest that oral reading treatment may offer an efficient and effective means of addressing multisyllabic word production in AOS associated with nonfluent PPA, with lasting and generalized treatment effects.

Patterns of dysgraphia in primary progressive aphasia compared to post-stroke aphasia

We report patterns of dysgraphia in participants with primary progressive aphasia that can be explained by assuming disruption of one or more cognitive processes or representations in the complex process of spelling. These patterns are compared to those described in participants with focal lesions (stroke). Using structural imaging techniques, we found that damage to the left extrasylvian regions, including the uncinate, inferior fronto-occipital fasciculus, and sagittal stratum (including geniculostriate pathway and inferior longitudinal fasciculus), as well as other deep white and grey matter structures, was significantly associated with impairments in access to orthographic word forms and semantics (with reliance on phonology-to-orthography to produce a plausible spelling in the spelling to dictation task). These results contribute not only to our understanding of the patterns of dysgraphia following acquired brain damage but also the neural substrates underlying spelling.

Spelling intervention in post-stroke aphasia and primary progressive aphasia

Spelling–a core language skill–is commonly affected in neurological diseases such as stroke and Primary Progressive Aphasia (PPA). We present two case studies of the same spelling therapy (learning of phoneme-to-grapheme correspondences with help from key words) in two participants: one who had a stroke and one with PPA (logopenic variant). Our study highlights similarities and differences in the time course of each indivdual's therapy. The study evaluates the effectiveness and generalization of treatment in each case, i.e. whether the treatment affected the trained items and/or untrained items, and whether or not the treatment gains were maintained after the end of therapy. Both participants were able to learn associations between phonemes and graphemes as well as between phonemes and words. Reliable generalization to untrained words was shown only for the participant with post-stroke aphasia, but we were not able to test generalization to untrained words in the individual with PPA. The same spelling therapy followed a different time course in each case. The participant with post-stroke aphasia showed a lasting effect of improved spelling, but we were unable to assess maintenance of improvement in the participant with PPA. We discuss these differences in light of the underlying nature of each disease.

Treatment for apraxia of speech in nonfluent variant primary progressive aphasia

There is a growing body of literature examining the utility of behavioral treatment in primary progressive aphasia (PPA). There are, however, no studies exploring treatment approaches to improve speech production in individuals with apraxia of speech (AOS) associated with the nonfluent variant of PPA. The purpose of this study was to examine a novel approach to treatment of AOS in nonfluent PPA. We implemented a treatment method using structured oral reading as a tool for improving production of multisyllabic words in an individual with mild AOS and nonfluent variant PPA. Our participant showed a reduction in speech errors during reading of novel text that was maintained at one year post-treatment. Generalization of improved speech production was observed on repetition of words and sentences and the participant showed stability of speech production over time in connected speech. Results suggest that oral reading treatment is an efficient and effective means of addressing multisyllabic word production in AOS associated with nonfluent PPA, with lasting and generalized treatment effects.

Nonpharmacological interventions for cognitive impairments following primary progressive aphasia: a systematic review of the literature

This study provided a systematic review on nonpharmacological interventions applied to patients diagnosed with Primary Progressive Aphasia (PPA) and its variants: Semantic (SPPA), Nonfluent (NFPPA) and Logopenic (LPPA) to establish evidence-based recommendations for the clinical practice of cognitive rehabilitation for these patients.

METHODS

A PubMed and LILACS literature search with no time restriction was conducted with the keywords PPA (and its variants) AND rehabilitation OR training OR intervention OR therapy OR treatment OR effectiveness. To develop its evidence-based recommendations, a research committee identified questions to be addressed and determined the level of evidence for each study according to published criteria (Cicerone et al., 2000). Overall evidence for treatments was summarized and recommendations were derived.

RESULTS

Our search retrieved articles published from 1995 to 2013: 21 for SPPA, 8 for NFPPA, 3 for LPPA and 8 for PPA with no specification. Thirty-five studies were rated as Class III, consisting of studies with results obtained from one or more single-cases and that used appropriate single-subject methods with adequate quantification and analysis of results. The level of evidence of three functional interventions could not be established. One study was rated as Class II and consisted of a nonrandomized case-control investigation.

CONCLUSION

Positive results were reported in all reviewed studies. However, in order to be recommended, some investigation regarding the intervention efficacy was required. Results of the present review allows for recommendation of some nonpharmacological interventions for cognitive deficits following PPA as Practice Options. Suggestions for further studies on PPA interventions and future research are discussed.

Neuroimaging in aphasia treatment research: issues of experimental design for relating cognitive to neural changes

The design of functional neuroimaging studies investigating the neural changes that support treatment-based recovery of targeted language functions in acquired aphasia faces a number of challenges. In this paper, we discuss these challenges and focus on experimental tasks and experimental designs that can be used to address the challenges, facilitate the interpretation of results and promote integration of findings across studies.

Treatment for Progressive Impairments of Language

Primary progressive aphasia (PPA) is a relatively new diagnostic entity, for which few behavioral treatments have been investigated. Recent work has helped to clarify the nature of distinct PPA variants, including a nonfluent variant (NFV-PPA), a logopenic variant (LV-PPA), and a semantic variant (SV-PPA). This paper reviews treatment research to date in each subtype of PPA, including restitutive, augmentative, and functional approaches. The evidence suggests that restitutive behavioral treatment can result in improved or stabilized language performance within treated domains. Specifically, sentence production and lexical retrieval have been addressed in NFV-PPA, whereas lexical retrieval has been the primary object of treatment in LV and SV-PPA. Use of augmentative communication techniques, as well as implementation of functional communication approaches, also may result in improved communication skills in individuals with PPA. The ideal treatment approach may be one that combines restitutive, augmentative, and functional approaches to treatment, in order to maximize residual cognitive-linguistic skills in patients. Additional research is warranted to determine which modes of treatment are most beneficial in each type of PPA at various stages of severity.