Transcranial Direct Current Stimulation Paired With Verb Network Strengthening Treatment Improves Verb Naming in Primary Progressive Aphasia: A Case Series

Dynamics of oral language and speech production through neuromodulation: A systematic review of non-invasive brain stimulation in neurodegeneration

Oral language and speech production analyses are emerging as innovative indicators of neurodegeneration. These components of expressive discourse permit dementia identification at early stages, even in neurodegenerative pathologies with non-dominant linguistic symptomatology. Simultaneously, non-invasive brain stimulation (NIBS) has been described as an effective neuromodulation technique to counter neurodegenerative symptoms. This systematic review assesses whether neuromodulation via NIBS can impact oral expressive discourse through oral language and speech production parameters in neurodegenerative contexts. We conducted a systematic review of NIBS studies reporting longitudinal changes of oral expressive output tasks in patients with a neurodegenerative condition. A systematic search of studies published between 2011 and 2024 was performed from four databases (Scopus, PubMed, PsycINFO, Embase). Data analysis yielded 27 relevant studies with quality assessed using the Cochrane RoB2 and JBI tools This review suggests that neuromodulation via NIBS can positively influence oral expression capacities. Nonetheless, neuromodulation impact varies based on clinical diagnosis, intervention parameters, and patient demographics. Speech production measures appear more sensitive to neuromodulation than oral production capability scores. Neuroimaging data further reveals that speech production longitudinal changes appear linked to NIBS-induced changes in brain activity. In that sense, speech and oral language production parameters emerge as potential sensitive indicators of neuromodulation effects and neurodegenerative symptomatology fluctuations. This review highlights the potential of NIBS in enhancing speech and oral language production in neurodegenerative conditions, highlighting the importance of personalized interventions and multidimensional assessment approaches. Future research should explore the integration of speech markers as progressive indicators of both symptomatic and neural developments.

Behavioral and neural effects of temporoparietal high-definition transcranial direct current stimulation in logopenic variant primary progressive aphasia: a preliminary study

Background

High-definition-tDCS (HD-tDCS) is a recent technology that allows for localized cortical stimulation, but has not yet been investigated as an augmentative therapy while targeting the left temporoparietal cortex in logopenic variant PPA (lvPPA). The changes in neuronal oscillatory patterns and resting-state functional connectivity in response to HD-tDCS also remains poorly understood.

Objective

We sought to investigate the effects of HD-tDCS with phonologic-based language training on language, cognition, and resting-state functional connectivity in lvPPA.

Methods

We used a double-blind, within-subject, sham-controlled crossover design with a 4-month between-treatment period in four participants with lvPPA. Participants completed language, cognitive assessments, and imaging with magnetoencephalography (MEG) and resting-state functional MRI (fMRI) prior to treatment with either anodal HD-tDCS or sham targeting the left supramarginal gyrus over 10 sessions. Language and cognitive assessments, MEG, and fMRI were repeated after the final session and at 2 months follow-up. Preliminary data on efficacy was evaluated based on relative changes from baseline in language and cognitive scores. Language measures included metrics derived from spontaneous speech from picture description. Changes in resting-state functional connectivity within the phonological network were analyzed using fMRI. Magnitudes of source-level evoked responses and hemispheric laterality indices from language task-based MEG were used to assess changes in cortical engagement induced by HD-tDCS.

Results

All four participants were retained across the 4-month between-treatment period, with satisfactory blinding of participants and investigators throughout the study. Anodal HD-tDCS was well tolerated with a side effect profile that did not extend past the immediate treatment period. No benefit of HD-tDCS over sham on language and cognitive measures was observed in this small sample. Functional imaging results using MEG and fMRI indicated an excitatory effect of anodal HD-tDCS compared to sham and suggested that greater temporoparietal activation and connectivity was positively associated with language outcomes.

Conclusion

Anodal HD-tDCS to the inferior parietal cortex combined with language training appears feasible and well tolerated in participants with lvPPA. Language outcomes may be explained by regression to the mean, and to a lesser degree, by ceiling effects and differences in baseline disease severity. The intervention has apparent temporoparietal correlates, and its clinical efficacy should be further studied in larger trials.

Clinical trial registration

ClinicalTrials.gov, Number NCT03805659.

Feasibility of home-based transcranial direct current stimulation combined with personalized word retrieval for improving naming in primary progressive aphasia

Background/Objectives

Primary progressive aphasia (PPA) is managed with speech-language therapy (SLT) to slow language decline. Pairing transcranial direct current stimulation (tDCS) with SLT can enhance its effects. However, further research is needed to confirm these findings and guide its clinical use. We evaluated the feasibility of providing an intervention combining tDCS with SLT as a home-based and remotely supervised intervention.

Methods

Participants with confirmed PPA who had word-finding difficulties were recruited for an open-label observational study. The intervention consisted of 20 daily sessions over 1 month, each with 45-min of personalized word retrieval training. During the first 30-min, participants received tDCS over the left inferior frontal gyrus (anode F7, cathode O1) at 2.0 mA. Language measures were remotely administered at baseline and intervention end.

Results

We enrolled 10 patients (age: 70 ± 7 years; 60% male) with confirmed logopenic variant (n = 2), semantic variant (n = 2), or unspecified (n = 6) PPA. The intervention was well-tolerated with no treatment-limiting adverse events. All participants completed all sessions, confirming the feasibility of the home-based treatment. There were no declines in language functioning measures, with improved naming for trained vs. untrained items (p = 0.003) and a significant improvement in confrontation naming (p = 0.016) from baseline to intervention end.

Conclusions

Our case series demonstrates that home-based tDCS added to SLT is feasible for patients with PPA. However, larger controlled studies are required to confirm its effectiveness in slowing language decline and to fully determine the benefits of this approach. This approach not only facilitates broader access to participation but also enables the extended treatment necessary to evaluate its clinical benefits, moving this treatment closer to clinical availability as a telehealth treatment.

Augmenting Verb-Naming Therapy With Neuromodulation Decelerates Language Loss in Primary Progressive Aphasia

PURPOSE

The purpose of the study was to evaluate Verb Network Strengthening Treatment (VNeST) paired with the transcranial direct current stimulation (tDCS) of the left inferior frontal gyrus, which was compared to VNeST paired with a sham stimulation in primary progressive aphasia (PPA).

METHOD

A double-blind, within-subject, sham-controlled crossover design was used. Eight participants with PPA were enrolled. Participants were enrolled in two treatment phases, one with VNeST plus real tDCS and one with VNeST plus sham. Participants received fifteen 1-hr sessions of VNeST in each phase. Linear mixed-effects models were used to compare changes between baseline and two follow-up time points (1 week and 8 weeks posttreatment) in naming trained verbs, untrained verbs, and untrained nouns; sentence production and comprehension; and producing content units and complete utterances in discourse.

RESULTS

VNeST was effective for significantly improving naming trained verbs and producing more complete utterances in discourse at 1 week posttreatment in both tDCS and sham conditions. A significant tDCS advantage yielded generalization of treatment effects to untrained verbs (at 1 week and 8 weeks posttreatment), sentence production (at 1 week posttreatment), and sentence comprehension (at 8 weeks posttreatment). Untrained verb naming and sentence comprehension declined when VNeST was not augmented with tDCS.

CONCLUSIONS

Our findings provide emerging evidence that VNeST paired with tDCS can improve word finding, and other language abilities, in people with PPA. VNeST without neuromodulation can improve trained verb naming, but untrained verbs will likely decline faster when VNeST is not augmented with tDCS. Future research is required with a larger sample size to continue investigating the potential of treating word finding with VNeST and tDCS in PPA.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.27914325.

Long-term, home-based transcranial direct current stimulation coupled with computerized cognitive training in frontotemporal dementia: A case report

We present the case of a 62-year-old woman with probable behavioral variant of frontotemporal dementia (bvFTD) with cognitive/language deficits who demonstrated improved performance on cognitive/language testing and in functional tasks following long-term, home-based transcranial direct current stimulation (tDCS) coupled with computerized cognitive training (CCT). The patient underwent home-based tDCS (anode on the left prefrontal cortex and cathode on the right homologue) for 46 sessions over 10 weeks along with CCT. On post-treatment testing, the patient improved by 3 points on the Mini-Mental State Exam (MMSE) (23 to 26). She also showed improvement on several cognitive/language tasks, such as immediate recall of single words and word pairs, total accurate words in sentence repetition, delayed recall, semantic processing, and sentence level comprehension. There was no decline in several other cognitive and language tasks. Family members reported subjective improvements in expressiveness, communication, and interaction with others as well as increased attention to grooming and style which contrasted with her pre-treatment condition. This report suggests that home-based tDCS combined with CCT for an extended period may slow decline, and improve cognitive/language performance and everyday function in FTD.

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.

Baseline Conceptual-Semantic Impairment Predicts Longitudinal Treatment Effects for Anomia in Primary Progressive Aphasia and Alzheimer's Disease

Background

An individual's diagnostic subtype may fail to predict the efficacy of a given type of treatment for anomia. Classification by conceptual-semantic impairment may be more informative.

Aims

This study examined the effects of conceptual-semantic impairment and diagnostic subtype on anomia treatment effects in primary progressive aphasia (PPA) and Alzheimer's disease (AD).

Methods & Procedures

At baseline, the picture and word versions of the Pyramids and Palm Trees and Kissing and Dancing tests were used to measure conceptual-semantic processing. Based on norming that was conducted with unimpaired older adults, participants were classified as being impaired on both the picture and word versions (i.e., modality-general conceptual-semantic impairment), the picture version (Objects or Actions) only (i.e., visual-conceptual impairment), the word version (Nouns or Verbs) only (i.e., lexical-semantic impairment), or neither the picture nor the word version (i.e., no impairment). Following baseline testing, a lexical treatment and a semantic treatment were administered to all participants. The treatment stimuli consisted of nouns and verbs that were consistently named correctly at baseline (Prophylaxis items) and/or nouns and verbs that were consistently named incorrectly at baseline (Remediation items). Naming accuracy was measured at baseline, and it was measured at three, seven, eleven, fourteen, eighteen, and twenty-one months.

Outcomes & Results

Compared to baseline naming performance, lexical and semantic treatments both improved naming accuracy for treated Remediation nouns and verbs. For Prophylaxis items, lexical treatment was effective for both nouns and verbs, and semantic treatment was effective for verbs, but the pattern of results was different for nouns -- the effect of semantic treatment was initially nonsignificant or marginally significant, but it was significant beginning at 11 Months, suggesting that the effects of prophylactic semantic treatment may become more apparent as the disorder progresses. Furthermore, the interaction between baseline Conceptual-Semantic Impairment and the Treatment Condition (Lexical vs. Semantic) was significant for verb Prophylaxis items at 3 and 18 Months, and it was significant for noun Prophylaxis items at 14 and 18 Months.

Conclusions

The pattern of results suggested that individuals who have modality-general conceptual-semantic impairment at baseline are more likely to benefit from lexical treatment, while individuals who have unimpaired conceptual-semantic processing at baseline are more likely to benefit from semantic treatment as the disorder progresses. In contrast to conceptual-semantic impairment, diagnostic subtype did not typically predict the treatment effects.

Treatment of primary progressive aphasia by repetitive transcranial magnetic stimulation: a randomized, double-blind, placebo-controlled study

To evaluate the efficacy of high-frequency repetitive transcranial magnetic stimulation (rTMS) in patients with primary progressive aphasia (PPA). In this randomized, double-blind trial in a single center, patients who were diagnosed with PPA were randomly assigned to receive either real rTMS or sham rTMS treatment. High-frequency rTMS was delivered to the dorsolateral prefrontal cortex (DLPFC). The primary outcome was the change in Boston Naming Test (BNT) score at each follow-up compared to the baseline. The secondary outcomes included change in CAL (Communicative Activity Log) and WAB (Western Aphasia Battery) compared to baseline and neuropsychological assessments. Forty patients (16 with nonfluent, 12 with semantic and 12 with logopenic variant PPA) were enrolled and randomly assigned to the rTMS or sham rTMS group, with 20 patients in each group. Thirty-five patients (87.5%) completed a 6-month follow-up. Compared to the sham rTMS group, the BNT improvement and WAB improvement in the real rTMS group were significantly higher. These significant improvements could be observed throughout the entire 6-month follow-up. At 1 month and 3 months after treatment, CAL improvements of real rTMS were significantly higher than sham rTMS. The improvements in BNT, CAL and WAB did not significantly differ among PPA variants. No significant improvement in neuropsychological assessments was observed. High-frequency rTMS delivered to DLPFC improved language functions in patients with different PPA variants. The efficacy was still observed after 6 months of treatment. Trial registration: NCT04431401 ( https://clinicaltrials.gov/ct2/show/NCT04431401 ).