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

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.

Atypical Alzheimer's dementia: Addressing the subtypes, epidemiology, atypical presentations, diagnostic biomarkers, and treatment updates

Alzheimer's disease is a progressive neurodegenerative disorder that primarily affects the elderly population; and is characterized by the gradual loss of memory, cognition, and ability to carry out daily activities. However, a growing body of research indicates that there exists a subtype of Alzheimer's disease known as Atypical Alzheimer's disease. Atypical Alzheimer's disease is a rare form of dementia that differs from the typical presentation of Alzheimer's disease, such as variations in the age of onset, distribution of brain pathology, and clinical symptoms. The patients affected have a younger age of onset and have predominantly visual, language, executive function, motor, and behavioral dysfunction. The diagnosis requires a comprehensive neurological evaluation with specific attention to cognitive and behavioral changes while ruling out other potential causes of dementia. Emerging biomarkers including CSF profiles, amyloid and tau PET imaging, and advanced neuroimaging techniques offer promising avenues for improving diagnostic accuracy and understanding disease mechanisms. In this article, we focus on atypical presentations seen in the posterior cortical variant, frontal variant, progressive aphasic variant, corticobasal syndrome and look at the specific biomarkers used in the diagnosis of each variant along with focusing on the treatment of the disease. We also aim to provide an understanding of Atypical Alzheimer's disease, its clinical features, the biomarkers helping in diagnosing the disease, the current treatment guidelines, and the current scientific advancements in the field.

Safety and Efficacy of Different Therapeutic Interventions for Primary Progressive Aphasia: A Systematic Review

Background: Primary progressive aphasia (PPA) is a neurodegenerative disorder that worsens over time without appropriate treatment. Although referral to a speech and language pathologist is essential for diagnosing language deficits and developing effective treatment plans, there is no scientific consensus regarding the most effective treatment. Thus, our study aims to assess the efficacy and safety of various therapeutic interventions for PPA. Methods: Google Scholar, PubMed, Web of Science, and the Cochrane Library databases were systematically searched to identify articles assessing different therapeutic interventions for PPA. To ensure comprehensive coverage, the search strategy employed specific medical subject headings. The primary outcome measure was language gain; the secondary outcome assessed overall therapeutic effects. Data on study characteristics, patient demographics, PPA subtypes, therapeutic modalities, and treatment patterns were collected. Results: Fifty-seven studies with 655 patients were included. For naming and word finding, errorless learning therapy, lexical retrieval cascade (LRC), semantic feature training, smartphone-based cognitive therapy, picture-naming therapy, and repetitive transcranial magnetic stimulation (rTMS) maintained effects for up to six months. Repetitive rTMS, video-implemented script training for aphasia (VISTA), and structured oral reading therapy improved speech fluency. Sole transcranial treatments enhanced auditory verbal comprehension, whereas transcranial direct current stimulation (tDCS) combined with language or cognitive therapy improved repetition abilities. Phonological and orthographic treatments improved reading accuracy across PPA subtypes. tDCS combined with speech therapy enhanced mini-mental state examination (MMSE) scores and cognitive function. Several therapies, including smartphone-based cognitive therapy and VISTA therapy, demonstrated sustained language improvements over six months. Conclusions: Various therapeutic interventions offer potential benefits for individuals with PPA. However, due to the heterogeneity in study designs, administration methods, small sample sizes, and lack of standardized measurement methods, drawing a firm conclusion is difficult. Further studies are warranted to establish evidence-based treatment protocols.

Effects of single-session repetitive transcranial magnetic stimulation to identify the optimal brain target in primary progressive aphasia

BACKGROUND

Non-invasive brain stimulation has shown positive results in maximizing the effects of language therapy in primary progressive aphasia (PPA). Due to the different patterns of brain damage in each aphasia variant, we hypothesized that patients with non-fluent and semantic variants would show a differential response to transcranial magnetic stimulation (TMS).

OBJECTIVE

We aimed to compare the clinical responses after a single session of repetitive TMS in the left inferior frontal gyrus (IFG) and the left dorsolateral prefrontal cortex (DLPC).

METHODOLOGY

Twenty patients with PPA (14 with non-fluent and 6 with semantic variants) were assessed before and after repetitive TMS over the IFG, DLPC, and vertex with several language tasks, connected speech, and a subjective impression of change scale.

RESULTS

IFG stimulation was associated with an improvement in words per minute and the subjective assessment in the non-fluent variant, but no effects were found in the semantic variant. DLPC stimulation was associated with an improvement in words per minute, repetition, and naming latency in the non-fluent variant, and in naming and subjective impression of change in the semantic variant.

CONCLUSIONS

Our study showed a differential effect of one session of brain stimulation over the IFG and DLPC in patients with non-fluent and semantic PPA variants. These findings suggest that the selection of the target of stimulation may be relevant for the success of brain stimulation and favor the use of DLPC over the IFG.

Noninvasive Brain Stimulation in Primary Progressive Aphasia with and Without Concomitant Speech and Language Therapy: Systematic Review and Meta-analysis

Primary progressive aphasias (PPA) represent a group of neurodegenerative conditions affecting verbal communication abilities for which no effective medication is currently available. Noninvasive brain stimulation (NiBS) has been mainly explored as adjunctive therapy to conventional speech and language therapy (SLT) with promising results. The present meta-analysis of randomized-controlled trials (RCTs) aims to evaluate the efficacy of NiBS in PPA patients on a range of linguistic tasks (naming, phonemic fluency, semantic fluency). A literature search was carried out using EMBASE and PUBMED, searching for multi-session RCTs administering NiBS on PPA patients as stand-alone or with SLT. The results were not significant overall, indicating a null difference between the active and the sham condition on language functions; pooled effects tended to be higher in parallel than in crossover studies and for follow-ups than post-treatment. In the naming analyses, the combined effects for the studies that coupled NiBS with SLT were slightly higher than the overall effect at each time point, although not significant. These results need to be considered with caution given the low number of included studies and small sample sizes, but offer relevant indications for future research in terms of optimal treatment protocols and personalization of therapies.

Efficacy and safety of transcranial magnetic stimulation on cognition in mild cognitive impairment, Alzheimer's disease, Alzheimer's disease-related dementias, and other cognitive disorders: a systematic review and meta-analysis

OBJECTIVE

We aim to analyze the efficacy and safety of TMS on cognition in mild cognitive impairment (MCI), Alzheimer's disease (AD), AD-related dementias, and nondementia conditions with comorbid cognitive impairment.

DESIGN

Systematic review, Meta-Analysis.

SETTING

We searched MEDLINE, Embase, Cochrane database, APA PsycINFO, Web of Science, and Scopus from January 1, 2000, to February 9, 2023.

PARTICIPANTS AND INTERVENTIONS

RCTs, open-label, and case series studies reporting cognitive outcomes following TMS intervention were included.

MEASUREMENT

Cognitive and safety outcomes were measured. Cochrane Risk of Bias for RCTs and MINORS (Methodological Index for Non-Randomized Studies) criteria were used to evaluate study quality. This study was registered with PROSPERO (CRD42022326423).

RESULTS

The systematic review included 143 studies (n = 5,800 participants) worldwide, encompassing 94 RCTs, 43 open-label prospective, 3 open-label retrospective, and 3 case series. The meta-analysis included 25 RCTs in MCI and AD. Collectively, these studies provide evidence of improved global and specific cognitive measures with TMS across diagnostic groups. Only 2 studies (among 143) reported 4 adverse events of seizures: 3 were deemed TMS unrelated and another resolved with coil repositioning. Meta-analysis showed large effect sizes on global cognition (Mini-Mental State Examination (SMD = 0.80 [0.26, 1.33], p = 0.003), Montreal Cognitive Assessment (SMD = 0.85 [0.26, 1.44], p = 0.005), Alzheimer's Disease Assessment Scale-Cognitive Subscale (SMD = -0.96 [-1.32, -0.60], p < 0.001)) in MCI and AD, although with significant heterogeneity.

CONCLUSION

The reviewed studies provide favorable evidence of improved cognition with TMS across all groups with cognitive impairment. TMS was safe and well tolerated with infrequent serious adverse events.

A Critical Review of Noninvasive Brain Stimulation Technologies in Alzheimer's Dementia and Primary Progressive Aphasia

Multiple pharmacologic agents now have been approved in the United States and other countries as treatment to slow disease and clinical progression for Alzheimer's disease. Given these treatments have not been proven to lessen the cognitive deficits already manifested in the Alzheimer's Clinical Syndrome (ACS), and none are aimed for another debilitating dementia syndrome identified as primary progressive aphasia (PPA), there is an urgent need for new, safe, tolerable, and efficacious treatments to mitigate the cognitive deficits experienced in ACS and PPA. Noninvasive brain stimulation has shown promise for enhancing cognitive functioning, and there has been interest in its potential therapeutic value in ACS and PPA. This review critically examines the evidence of five technologies in ACS and PPA: transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), transcranial random noise stimulation (tRNS), repetitive transcranial magnetic stimulation (rTMS), and noninvasive vagus nerve stimulation (nVNS). Many randomized controlled trials of tDCS and rTMS report positive treatment effects on cognition in ACS and PPA that persist out to at least 8 weeks, whereas there are few trials for tACS and none for tRNS and nVNS. However, most positive trials did not identify clinically meaningful changes, underscoring that clinical efficacy has yet to be established in ACS and PPA. Much is still to be learned about noninvasive brain stimulation in ACS and PPA, and shifting the focus to prioritize clinical significance in addition to statistical significance in trials could yield greater success in understanding its potential cognitive effects and optimal parameters.