AI and Aphasia in the Digital Age: A Critical Review

Aphasiology has a long and rich tradition of contributing to understanding how culture, language, and social environment contribute to brain development and function. Recent breakthroughs in AI can transform the role of aphasiology in the digital age by leveraging speech data in all languages to model how damage to specific brain regions impacts linguistic universals such as grammar. These tools, including generative AI (ChatGPT) and natural language processing (NLP) models, could also inform practitioners working with clinical populations in the assessment and treatment of aphasia using AI-based interventions such as personalized therapy and adaptive platforms. Although these possibilities have generated enthusiasm in aphasiology, a rigorous interrogation of their limitations is necessary before AI is integrated into practice. We explain the history and first principles of reciprocity between AI and aphasiology, highlighting how lesioning neural networks opened the black box of cognitive neurolinguistic processing. We then argue that when more data from aphasia across languages become digitized and available online, deep learning will reveal hitherto unreported patterns of language processing of theoretical interest for aphasiologists. We also anticipate some problems using AI, including language biases, cultural, ethical, and scientific limitations, a misrepresentation of marginalized languages, and a lack of rigorous validation of tools. However, as these challenges are met with better governance, AI could have an equitable impact.

Therapies and Challenges in the Post-Stroke Aphasia Rehabilitation Arena: Current and Future Prospects

Aphasia is a serious consequence of stroke that results in a breakdown in communication. The course of aphasia recovery differs between afflicted individuals, and responsiveness to treatment cannot be predicted. Aphasiologists continue to investigate numerous behavioral treatment protocols that have shifted their focus to complimentary rehabilitation strategies. The aim of this study is threefold. First, to summarize the different categories of aphasia interventions post-stroke, considering their respective protocols, and present available evidence on the effectiveness of those protocols. Second, to document the challenges regarding the prediction of aphasia treatment response post-stroke in individual patients. Third, to report the challenges faced by researchers in recruiting people with aphasia (PWA) for treatment studies, and provide recommendations on how to increase participant recruitment and retention. This study provides up-to-date information on (i) effective therapies and aphasia recovery processes, and (ii) research recruitment hurdles together with potential strategies for overcoming them.

Better long-term speech outcomes in stroke survivors who received early clinical speech and language therapy: What's driving recovery?

Establishing whether speech and language therapy after stroke has beneficial effects on speaking ability is challenging because of the need to control for multiple non-therapy factors known to influence recovery. We investigated how speaking ability at three time points post-stroke differed in patients who received varying amounts of clinical therapy in the first month post-stroke. In contrast to prior studies, we factored out variance from: initial severity of speaking impairment, amount of later therapy, and left and right hemisphere lesion size and site. We found that speaking ability at one month post-stroke was significantly better in patients who received early therapy (n = 79), versus those who did not (n = 64), and the number of hours of early therapy was positively related to recovery at one year post-stroke. We offer two non-mutually exclusive interpretations of these data: (1) patients may benefit from the early provision of self-management strategies; (2) therapy is more likely to be provided to patients who have a better chance of recovery (e.g., poor physical and/or mental health may impact suitability for therapy and chance of recovery). Both interpretations have implications for future studies aiming to predict individual patients' speech outcomes after stroke, and their response to therapy.

Does acupuncture therapy improve language function of patients with aphasia following ischemic stroke? A systematic review and meta-analysis

BACKGROUND

Aphasia is one of the most common complications in patients with ischemic stroke. Studies have shown that acupuncture can improve the symptoms of aphasia patients. However, the effect of acupuncture on language function in patients with ischemic stroke is still controversial.

OBJECTIVE

This study aimed to critically assess the efficacy and safety of acupuncture for aphasia following ischemic stroke.

METHODS

PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Science Core Collection, China National Knowledge Infrastructure, Wanfang Digital Periodicals, and Chinese Science and Technology Periodicals database were searched. All randomized controlled trials (RCTs) that met the criteria were included.

RESULTS

Meta-analyses showed that mean difference in change of auditory comprehension score (MD = 7.71, 95% CI: 1.83 to 13.59, P = 0.01), spontaneous speech (MD = 2.77, 95% CI: 0.59 to 4.95, P = 0.01), repetition score (MD = 14.48, 95% CI: 11.04 to 17.91, P <  0.00001) and naming score (MD = 14.60, 95% CI: 11.33 to 17.88, P <  0.00001) measured by WAB scale were statistically significant. Subgroup analyses demonstrated that there were statistically significant mean differences in four items of WAB scale in patients with sub-acute stroke, and no statistically significant differences in patients with acute stroke.

CONCLUSION

The present study suggests that acupuncture may improve the language function of patients with aphasia following ischemic stroke, especially during the sub-acute phase. However, due to insufficient sample sizes and information on the safety, more high-quality RCTs are still needed.

Effects of computer-based therapy versus therapist-mediated therapy in stroke-related aphasia: Pilot non-inferiority study

PURPOSE

The burgeoning growth of computer-based rehabilitation technologies has led to a paradigm shift in the delivery of aphasia intervention. The aim of this study was to conduct a pilot non-inferiority study comparing computer-based training for people with aphasia versus traditional therapist-mediated training on language skills, functional communication and quality of life outcomes in the hospital setting.

METHODS

Twenty-two fluent, monolingual Italian speakers with stroke-related aphasia in the acute phase of recovery were enrolled in the study. Participants were assigned randomly to computer-based or therapist-mediated aphasia treatment. Both groups received one, 50-minute session for 5 days per week over a period of 8 weeks. During the training, they were administered words and sentence comprehension, written naming, word completion, fluency, word and sentence reorganization tasks. The complexity of each task was increased progressively based on the severity of each person's language deficits.

RESULTS

Participants in both computer-based and traditional therapist-mediated aphasia intervention showed significant gains in language skills, functional communication and quality of life from pre- to post-treatment. Statistically significant within-group differences were found across all outcome measures. In contrast, no significant between-group and group x time interaction effects were found across language skills, functional communication and quality-of-life measures.

CONCLUSIONS

The overall pattern of findings suggested computer-based intervention was not inferior to traditional therapist-based intervention for enhancing functional communication deficits in stroke-related aphasia during the acute phase of recovery. A follow-up, fully-powered clinical trial is needed to confirm the reliability of these results.

The Screening Test for Aphasia and Dysarthria (STAD) for Patients with Neurological Communicative Disorders: A Large-Scale, Multicenter Validation Study in Japan

INTRODUCTION

Evaluation of multiple domains, such as language, articulation, and cognitive function, is frequently required in neurological communicative disorders. The purpose of this study was to investigate the performance of a 10-min screening scale for estimating aphasia, dysarthria, and cognitive dysfunction using a multicenter, large-sized consecutive series.

METHODS

We conducted a multicenter validation study that included 314 patients with brain injury between February 1 and June 31, 2018, from 20 medical centers across Japan. The Screening Test for Aphasia and Dysarthria (STAD) was developed in Japan in 2009, and a previous smaller-scale retrospective study established its high to moderate validity. All patients had undergone the STAD, and 212 of them underwent the Western Aphasia Battery or Assessment of Motor Speech for Dysarthria. The effect size on all 29 items and receiver operating curves of 3 sections of the STAD were analyzed based on external criteria, which were decided considering the clinical diagnosis of aphasia, dysarthria, and cognitive dysfunction. Correlations between the STAD and reference tests were calculated.

RESULTS

The phi coefficients of 23 out of 29 items exceeded the moderate effect size of 0.3 toward the targeted disorder. Overall, there was a good balance between sensitivity (82-92%) and specificity (77-78%), with moderate to large positive and negative likelihood ratios (3.7-4.19 and 0.1-0.23). The Pearson's r between the verbal section and Western Aphasia Battery Aphasia Quotient, the articulation section and Assessment of Motor Speech for Dysarthria, and the nonverbal section and Western Aphasia Battery Nonlinguistic Skills were 0.89, 0.70, and 0.79, respectively.

CONCLUSION

We demonstrated that the STAD has acceptable content and concurrent validity for the assessment of communicative function in patients with brain injury. This short screening tool can be useful in specific contexts, such as in early bedside investigations, to obtain a quick summary of communicative function prior to the administration of other tests, and in cases where more in-depth testing is not feasible.

Current Approaches to the Treatment of Post-Stroke Aphasia

Aphasia, impairment of language after stroke or other neurological insult, is a common and often devastating condition that affects nearly every social activity and interaction. Behavioral speech and language therapy is the mainstay of treatment, although other interventions have been introduced to augment the effects of the behavioral therapy. In this narrative review, we discuss advances in aphasia therapy in the last 5 years and focus primarily on properly powered, randomized, controlled trials of both behavioral therapies and interventions to augment therapy for post-stroke aphasia. These trials include evaluation of behavioral therapies and computer-delivered language therapies. We also discuss outcome prediction trials as well as interventional trials that have employed noninvasive brain stimulation, or medications to augment language therapy. Supported by evidence from Phase III trials and large meta-analyses, it is now generally accepted that aphasia therapy can improve language processing for many patients. Not all patients respond similarly to aphasia therapy with the most severe patients being the least likely responders. Nevertheless, it is imperative that all patients, regardless of severity, receive aphasia management focused on direct therapy of language deficits, counseling, or both. Emerging evidence from Phase II trials suggests transcranial brain stimulation is a promising method to boost aphasia therapy outcomes.

Predictors of Poststroke Aphasia Recovery: A Systematic Review-Informed Individual Participant Data Meta-Analysis

BACKGROUND AND PURPOSE

The factors associated with recovery of language domains after stroke remain uncertain. We described recovery of overall-language-ability, auditory comprehension, naming, and functional-communication across participants' age, sex, and aphasia chronicity in a large, multilingual, international aphasia dataset.

METHODS

Individual participant data meta-analysis of systematically sourced aphasia datasets described overall-language ability using the Western Aphasia Battery Aphasia-Quotient; auditory comprehension by Aachen Aphasia Test (AAT) Token Test; naming by Boston Naming Test and functional-communication by AAT Spontaneous-Speech Communication subscale. Multivariable analyses regressed absolute score-changes from baseline across language domains onto covariates identified a priori in randomized controlled trials and all study types. Change-from-baseline scores were presented as estimates of means and 95% CIs. Heterogeneity was described using relative variance. Risk of bias was considered at dataset and meta-analysis level.

RESULTS

Assessments at baseline (median=43.6 weeks poststroke; interquartile range [4-165.1]) and first-follow-up (median=10 weeks from baseline; interquartile range [3-26]) were available for n=943 on overall-language ability, n=1056 on auditory comprehension, n=791 on naming and n=974 on functional-communication. Younger age (<55 years, +15.4 Western Aphasia Battery Aphasia-Quotient points [CI, 10.0-20.9], +6.1 correct on AAT Token Test [CI, 3.2-8.9]; +9.3 Boston Naming Test points [CI, 4.7-13.9]; +0.8 AAT Spontaneous-Speech Communication subscale points [CI, 0.5-1.0]) and enrollment <1 month post-onset (+19.1 Western Aphasia Battery Aphasia-Quotient points [CI, 13.9-24.4]; +5.3 correct on AAT Token Test [CI, 1.7-8.8]; +11.1 Boston Naming Test points [CI, 5.7-16.5]; and +1.1 AAT Spontaneous-Speech Communication subscale point [CI, 0.7-1.4]) conferred the greatest absolute change-from-baseline across each language domain. Improvements in language scores from baseline diminished with increasing age and aphasia chronicity. Data exhibited no significant statistical heterogeneity. Risk-of-bias was low to moderate-low.

CONCLUSIONS

Earlier intervention for poststroke aphasia was crucial to maximize language recovery across a range of language domains, although recovery continued to be observed to a lesser extent beyond 6 months poststroke.

Effect of Buyang Huanwu decoction for the rehabilitation of ischemic stroke patients: a meta-analysis of randomized controlled trials

Purpose

Buyang Huanwu decoction (BHD) is a widely used traditional Chinese medicine for the rehabilitation of ischemic stroke patients in China, but its clinical efficacy and safety have not been adequately assessed. In this paper, we conducted a systematic review and meta-analysis to evaluate the efficacy and safety of BHD.

Methods

We searched seven electronic databases from inception to 31 March 2019. The language was limited to Chinese and English. Randomized controlled trials evaluating the efficacy and safety of BHD for the rehabilitation of ischemic stroke patients were included in the meta-analysis. Reviewers independently performed the screening, data extraction, bias assessment, and data analysis. The treatment efficacy was pooled in a meta-analysis using RevMan 5.3 software with a random-effect model. Any disagreement was resolved by discussion among all reviewers. The PRISMA statement was used in the review process.

Results

A total of 11 studies with 1084 patients were included in the meta-analysis. The results suggested that BHD was superior to other treatments in terms of clinical efficacy in symptoms and daily activities (n = 684, RR = 1.12, 95% CI: 0.99 to 1.27), clinical efficacy in TCM symptoms (n = 280, RR = 1.45, 95% CI: 1.03 to 2.03), National Institute of Health stroke scale (n = 192, MD = 1.66, 95% CI: -1.08 to 4.40), and activities of daily living (n = 200, MD = 8.20, 95% CI: -3.95 to 20.35).

Conclusions

The results supported the clinical use of BHD for the rehabilitation of ischemic stroke patients. However, the methodological qualities of the included studies were relatively low, and there were limited reports on adverse events. The clinical efficacy and safety of BHD need to be further confirmed by more well-designed and high-quality randomized controlled trials to warrant the clinical recommendation of BHD for the rehabilitation of ischemic stroke patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12955-021-01728-6.

An Efficient Bedside Measure Yields Prognostic Implications for Language Recovery in Acute Stroke Patients

BACKGROUND

It is estimated that ∼30% of stroke survivors have aphasia, a language disorder resulting from damage to left-hemisphere language networks. In acute care settings, efficient identification of aphasia is critical, but there is a paucity of efficient bedside assessments.

OBJECTIVE

To determine whether objective measures on a picture description task administered within 48 hours post stroke (a) predict language recovery, (b) estimate left-hemisphere lesion volume and location, and (c) correlate with other bedside language assessments.

METHOD

Behavioral data were scored at acute and chronic time points. Neuroimaging data were used to determine associations between the picture description task, other language assessments, and lesion volume and location.

RESULTS

Acute content units, age, and total lesion volume predicted communication recovery; F3,18 = 3.98, P = 0.024; r = 0.40. Significant correlations were found between the picture description task and lesion volume and location. Picture description outcomes were also associated with other clinical language assessments.

DISCUSSION

This picture description task quickly predicted the language performance (communication recovery and outcome) for patients who suffered a left-hemisphere stroke. Picture description task measures correlated with damage in the left hemisphere and with other, more time-consuming and cumbersome language assessments that are typically administered acutely at bedside.

CONCLUSION

The predictive value of this picture description task and correlations with existing language assessments substantiate the clinical importance of a reliable yet rapid bedside measure for acute stroke patients that can be administered by a variety of health care professionals.

Clinical Implementation of Transcranial Direct Current Stimulation in Aphasia: A Survey of Speech-Language Pathologists

Purpose The objectives of this study are to (a) identify speech-language pathologists' (SLPs') familiarity with transcranial direct current stimulation (tDCS), (b) quantify what SLPs consider necessary tDCS-related improvement in aphasia severity (i.e., tDCS enhancement; desired improvement above and beyond traditional behavioral therapy) to implement this adjuvant therapy for the clinical management of aphasia, and (c) identify concerns that could potentially hinder the clinical adoption of tDCS. Method A brief (14-question) survey was disseminated via e-mail and social media outlets targeting SLPs working with individuals with aphasia. Results Two hundred twenty-one individuals responded, and 155 valid surveys were analyzed. Seventy-one percent of participants reported familiarity with tDCS prior to taking the survey. Clinicians reported a desired mean enhancement of 22.9% additional points on the Western Aphasia Battery-Revised Aphasia Quotient. Importantly, 94.2% of SLPs reported concerns regarding the implementation of tDCS in clinical settings (i.e., safety, cost, administrative approval, reimbursement and training). Conclusions This is the first study to identify SLPs' perspectives regarding the clinical adoption of tDCS. Results suggest the majority of queried SLPs were familiar with tDCS prior to taking the survey. Although SLPs report a desired improvement of approximately 23% additional points on the Western Aphasia Battery-Revised Aphasia Quotient to consider adopting tDCS into practice, many SLPs reported concerns regarding clinical adoption. Responses from the current survey offer important preliminary evidence to begin bridging the research-to-practice gap as it relates to the clinical implementation of tDCS. Relatedly, these results will inform future clinical trials.

Computerized Training in Poststroke Aphasia: What About the Long-Term Effects? A Randomized Clinical Trial

BACKGROUND

Poststroke aphasia is a very disabling disorder, which may affect speech expression, comprehension, and reading or writing. Treatment of aphasia should be initiated as soon as possible after the brain injury; however, the improvement of language functions can occur also in the chronic phase.

MATERIALS AND METHODS

Thirty-two patients were randomly assigned to either an experimental group (17 patients) treated with computerized rehabilitation training (Power-Afa, Maddaloni, Campania, Italy) or a control group (15 patients), submitted to conventional speech therapy. Patients were trained 3 times a week for 8 weeks, (i.e., 24 sessions of 45 minutes each), and assessed at baseline (T0), at the end of each training (T1), and 3 months after the end of the treatment (T2).

RESULTS

The experimental group had a significant improvement from T0 to T1 in all the outcomes, whereas for the control group patients such an improvement was significant only concerning Functional Independence Measure and ideomotor praxis. Notably, the improvements in cognitive and language functions were maintained at 3-month follow-up only in the experimental group.

CONCLUSIONS

The software Power-Afa can be considered a valuable tool in improving the linguistic and cognitive recovery in patients affected by poststroke aphasia in the chronic phase. Further studies with larger samples and longer follow-up periods are needed to confirm such promising findings.

Early Recovery of Aphasia through Thrombolysis: The Significance of Spontaneous Speech

BACKGROUND

Aphasia is one of the most devastating stroke-related consequences for social interaction and daily activities. Aphasia recovery in acute stroke depends on the degree of reperfusion after thrombolysis or thrombectomy. As aphasia assessment tests are often time-consuming for patients with acute stroke, physicians have been developing rapid and simple tests. The aim of our study is to evaluate the improvement of language functions in the earliest stage in patients treated with thrombolysis and in nontreated patients using our rapid screening test.

MATERIALS AND METHODS

Our study is a single-center prospective observational study conducted at the Stroke Unit of the University Medical Hospital of Trieste (January-December 2016). Patients treated with thrombolysis and nontreated patients underwent 3 aphasia assessments through our rapid screening test (at baseline, 24 hours, and 72 hours). The screening test assesses spontaneous speech, oral comprehension of words, reading aloud and comprehension of written words, oral comprehension of sentences, naming, repetition of words and a sentence, and writing words.

RESULTS

The study included 40 patients: 18 patients treated with thrombolysis and 22 nontreated patients. Both groups improved over time. Among all language parameters, spontaneous speech was statistically significant between 24 and 72 hours (P value = .012), and between baseline and 72 hours (P value = .017).

CONCLUSIONS

Our study demonstrates that patients treated with thrombolysis experience greater improvement in language than the nontreated patients. The difference between the 2 groups is increasingly evident over time. Moreover, spontaneous speech is the parameter marked by the greatest improvement.

Efficacy of early cognitive-linguistic treatment for aphasia due to stroke: A randomised controlled trial (Rotterdam Aphasia Therapy Study-3)

Introduction

One third of patients with acute stroke have aphasia. The majority receive speech and language therapy. There is evidence for a beneficial effect of speech and language therapy on restoring communication, but it is unknown whether and how efficacy of speech and language therapy is influenced by timing of treatment. We studied whether speech and language therapy early after stroke by way of intensive cognitive-linguistic treatment is more effective than no speech and language therapy in the Rotterdam Aphasia Therapy Study-3, a multicentre randomised single-blind trial.

Methods and patients

Stroke patients with first-ever aphasia were randomised within 2 weeks of onset to either 4 weeks of early intensive cognitive-linguistic treatment (1 h/day) or no language treatment. Hereafter, both groups received regular speech and language therapy. Primary outcome was the score on the Amsterdam-Nijmegen Everyday Language Test, measuring everyday verbal communication, 4 weeks after randomisation. Secondary outcomes were Amsterdam-Nijmegen Everyday Language Test at 3 and 6 months. The study was powered to detect a clinically relevant difference of four points on the Amsterdam-Nijmegen Everyday Language Test.

Results

Of the 152 included patients, 80 patients were allocated to intervention. Median treatment intensity in the intervention-group was 24.5 h. The adjusted difference between groups in mean Amsterdam-Nijmegen Everyday Language Test-scores 4 weeks after randomisation was 0.39, 95% confidence interval: [-2.70 to 3.47], p = 0.805. No statistically significant differences were found at 3 and 6 months after randomisation either.

Conclusion

Four weeks of intensive cognitive-linguistic treatment initiated within 2 weeks of stroke is not more effective than no language treatment for the recovery of post-stroke aphasia. Our results exclude a clinically relevant effect of very early cognitive-linguistic treatment on everyday language.

Melodic Intonation Therapy in Chronic Aphasia: Evidence from a Pilot Randomized Controlled Trial

Melodic Intonation Therapy (MIT) is a language production therapy for severely non-fluent aphasic patients using melodic intoning and rhythm to restore language. Although many studies have reported its beneficial effects on language production, randomized controlled trials (RCT) examining the efficacy of MIT are rare. In an earlier publication, we presented the results of an RCT on MIT in subacute aphasia and found that MIT was effective on trained and untrained items. Further, we observed a clear trend in improved functional language use after MIT: subacute aphasic patients receiving MIT improved considerably on language tasks measuring connected speech and daily life verbal communication. Here, we present the results of a pilot RCT on MIT in chronic aphasia and compare these to the results observed in subacute aphasia. We used a multicenter waiting-list RCT design. Patients with chronic (>1 year) post-stroke aphasia were randomly allocated to the experimental group (6 weeks MIT) or to the control group (6 weeks no intervention followed by 6 weeks MIT). Assessments were done at baseline (T1), after 6 weeks (T2), and 6 weeks later (T3). Efficacy was evaluated at T2 using univariable linear regression analyses. Outcome measures were chosen to examine several levels of therapy success: improvement on trained items, generalization to untrained items, and generalization to verbal communication. Of 17 included patients, 10 were allocated to the experimental condition and 7 to the control condition. MIT significantly improved repetition of trained items (β = 13.32, p = 0.02). This effect did not remain stable at follow-up assessment. In contrast to earlier studies, we found only a limited and temporary effect of MIT, without generalization to untrained material or to functional communication. The results further suggest that the effect of MIT in chronic aphasia is more restricted than its effect in earlier stages post stroke. This is in line with studies showing larger effects of aphasia therapy in earlier compared to later stages post stroke. The study was designed as an RCT, but was underpowered. The results therefore have to be interpreted cautiously and future larger studies are needed.

CLINICAL TRIAL REGISTRATION

www.ClinicalTrials.gov, identifier NTR 1961.

Speech and language therapy for aphasia following subacute stroke

The aim of this study was to investigate the time window, duration and intensity of optimal speech and language therapy applied to aphasic patients with subacute stroke in our hospital. The study consisted of 33 patients being hospitalized for stroke rehabilitation in our hospital with first stroke but without previous history of speech and language therapy. Sixteen sessions of impairment-based speech and language therapy were applied to the patients, 30-60 minutes per day, 2 days a week, for 8 successive weeks. Aphasia assessment in stroke patients was performed with Gülhane Aphasia Test-2 before and after treatment. Compared with before treatment, fluency of speech, listening comprehension, reading comprehension, oral motor evaluation, automatic speech, repetition and naming were improved after treatment. This suggests that 16 seesions of speech and language therapy, 30-60 minutes per day, 2 days a week, for 8 successive weeks, are effective in the treatment of aphasic patients with subacute stroke.

Screening tests for aphasia in patients with stroke: a systematic review

Aphasia has a large impact on the quality of life and adds significantly to the costs of stroke care. Early recognition of aphasia in stroke patients is important for prognostication and well-timed treatment planning. We aimed to identify available screening tests for differentiating between aphasic and non-aphasic stroke patients, and to evaluate test accuracy, reliability, and feasibility. We searched PubMed, EMbase, Web of Science, and PsycINFO for published studies on screening tests aimed at assessing aphasia in stroke patients. The reference lists of the selected articles were scanned, and several experts were contacted to detect additional references. Of each screening test, we estimated the sensitivity, specificity, likelihood ratio of a positive test, likelihood ratio of a negative test, and diagnostic odds ratio (DOR), and rated the degree of bias of the validation method. We included ten studies evaluating eight screening tests. There was a large variation across studies regarding sample size, patient characteristics, and reference tests used for validation. Many papers failed to report on the consecutiveness of patient inclusion, time between aphasia onset and administration of the screening test, and blinding. Of the three studies that were rated as having an intermediate or low risk of bias, the DOR was highest for the Language Screening Test and ScreeLing. Several screening tools for aphasia in stroke are available, but many tests have not been verified properly. Methodologically sound validation studies of aphasia screening tests are needed to determine their usefulness in clinical practice.