Convenient Auditory-Based Language and Executive Function Test (CABLET)

Abstract

The Convenient Auditory-Based Language and Executive Function Test (CABLET) is a specialized, brief neuropsychological screening instrument developed by Ohdake et al. (2023) to rapidly identify cognitive impairment in individuals diagnosed with Amyotrophic Lateral Sclerosis (ALS). Given the relentless progression of physical disability, upper-limb weakness, and bulbar dysfunction inherent to ALS, conventional neuropsychological assessments that rely on manual dexterity, speeded motor execution, or intelligible speech production frequently yield confounded results or impose unacceptable physical burdens on patients. The CABLET resolves this fundamental challenge through an entirely receptive, auditory-based architecture utilizing spoken verbal stimuli.

The instrument is divided into two distinct components: Test 1, which screens word repetition and lexical judgment (administration time: approximately 1 minute; maximum score: 32 points), serving as both a functional linguistic check and a gating task; and Test 2, which systematically evaluates verbal short-term memory, working memory, and semantic knowledge using an adaptive span paradigm (maximum score: 40 points). The entire battery yields a maximum total score of 72 points and is administered via standard paper-and-pencil scoring protocols.

Psychometric evaluation demonstrated remarkable diagnostic performance. Receiver operating characteristic (ROC) analyses revealed an area under the curve (AUC) of 0.894 for the CABLET total score and 0.893 for Test 2. Specifically, Test 2 demonstrated an optimal sensitivity of 100% paired with a specificity of 71.4%, effectively identifying cognitive decline without diagnostic degradation when adjusting for age, educational attainment, or disease severity. The instrument demonstrated robust convergent validity with composite measures of ALS-specific cognitive functions (total score: r = 0.630; Test 2: r = 0.645; both p < 0.001) and established clear discriminant validity against ALS-nonspecific cognitive domains such as visuospatial and episodic memory (total score: r = 0.168, p = 0.208; Test 2: r = 0.166, p = 0.213).

Keywords

Cognitive Test, Auditory-Based Language, Rapid Detection of Cognitive Impairment, Executive Function Test, Amyotrophic Lateral Sclerosis, Cognitive Dysfunction, Executive Function, Neuropsychological Tests, Auditory Perception, Word Repetition, Lexical Judgment, Verbal Short-Term Memory, Semantics Knowledge.

Authors

The CABLET was conceptualized, designed, and clinically validated by a multidisciplinary team of neurologists, neuroscientists, and neuropsychologists based primarily in Aichi Prefecture, Japan:

• Reiko Ohdake, MD, PhD — Brain and Mind Research Center, Nagoya University, Nagoya, Japan.
• Hirohisa Watanabe, MD, PhD (Corresponding Author) — Department of Neurology, School of Medicine, Fujita Health University (1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi 470-1192, Japan; Email: [email protected]); Brain and Mind Research Center, Nagoya University, Nagoya, Japan.
• Kazuya Kawabata, MD, PhD (ORCID: 0000-0002-8851-4377) — Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
• Aya Ogura, MSc — Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
• Maki Sato, PhD — Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
• Yasuhiro Tanaka, MD, PhD — Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
• Kazunori Imai, MD — Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
• Michihito Masuda, MD, PhD — Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
• Toshiyasu Kato, MD, PhD — Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
• Takamasa Yokoi, MD, PhD — Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
• Kazuhiro Hara, MD, PhD — Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
• Ryoichi Nakamura, MD, PhD — Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
• Naoki Atsuta, MD, PhD — Department of Neurology, Aichi Medical University School of Medicine, Nagakute, Japan.
• Masafumi Nakagawa, MD, PhD — International University of Health and Welfare, Narita, Japan.
• Masahisa Katsuno, MD, PhD — Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
• Gen Sobue, MD, PhD — Brain and Mind Research Center, Nagoya University; Aichi Medical University, Nagakute, Japan.

Purpose

The primary purpose of the Convenient Auditory-Based Language and Executive Function Test (CABLET) is to provide clinicians and clinical researchers with an accurate, motor-minimized, rapid screening instrument designed to detect cognitive impairment in patients diagnosed with Amyotrophic Lateral Sclerosis (ALS). For decades, ALS was clinically categorized as a pure motor neuron pathology sparing higher cortical faculties. However, contemporary neuroimaging, pathological, and neuropsychological research has irrevocably established that ALS exists along a pathological continuum with Frontotemporal Dementia (FTD), linked pathologically by the aggregation of abnormal TDP-43 (TAR DNA-binding protein 43).

Epidemiological studies indicate that up to 50% of ALS patients demonstrate non-motor cognitive or behavioral alterations during their disease trajectory, with approximately 10% to 15% fulfilling full diagnostic criteria for comorbid frontotemporal dementia (ALS-FTD), and an additional 30% to 40% exhibiting discrete cognitive impairment predominantly localized to executive control, social cognition, and linguistic processing (ALSci). The presence of cognitive decline significantly impacts clinical outcomes, being strongly correlated with poor treatment compliance (such as refusal or mismanagement of non-invasive positive pressure ventilation and gastrostomy), accelerated disease progression, reduced survival times, and markedly elevated caregiver burden.

Despite the critical need for routine cognitive monitoring, standard bedside tests—such as the Mini-Mental State Examination (MMSE) or the Montreal Cognitive Assessment (MoCA)—exhibit marked psychometric invalidity when applied to this clinical demographic. These conventional instruments place heavy reliance on upper-extremity motor speed (e.g., trail making, clock drawing, copying intersecting figures) and fluent oral articulation (e.g., verbal fluency, sentence repetition). In ALS patients suffering from progressive paresis, muscular atrophy, fasciculations, or severe dysarthria, low scores often reflect neuromuscular failure rather than true cognitive breakdown.

Although specialized multidimensional tools such as the Edinburgh Cognitive and Behavioural ALS Screen (ECAS) have been developed to accommodate physical deficits, comprehensive batteries often require 30 to 45 minutes to administer. In routine outpatient clinics or at advanced disease stages characterized by respiratory compromise and pervasive physical exhaustion, an extensive assessment can precipitate profound cognitive fatigue, thereby skewing diagnostic precision. The CABLET addresses this critical clinical gap by providing a ultra-brief (Test 1 requiring ~1 minute, Test 2 requiring only several additional minutes), purely auditory-based assessment that imposes minimal output burden, facilitating high-throughput bedside detection of frontotemporal cognitive dysfunction.

Psychological Construct

The CABLET evaluates a constellation of cognitive faculties specifically vulnerable to frontotemporal neurodegeneration in motor neuron disease. Rather than measuring global intellect, the tool concentrates on discrete cognitive subdomains categorized within consensus criteria (Strong et al., 2017) as ALS-specific (executive functions, working memory, and language processing) while deliberately excluding ALS-nonspecific domains (visuospatial construction and non-verbal episodic memory).

1. Auditory-Verbal Processing and Repetition

The initial construct assessed within Test 1 involves the acoustic analysis of spoken language and the functional integrity of the phonological loop. By presenting verbal stimuli of varying phonetic and syllabic lengths, the test establishes whether the participant can perceive, decode, and audibly echo back phonemic tokens. This subscale serves an essential dual function: it measures basic receptive language and articulatory capability while establishing a gating threshold. If a patient cannot reproduce words due to profound dysarthria or severe auditory agnosia, continuing to executive testing is contraindicated to avoid invalid test results.

2. Lexical Judgment and Orthographic/Phonological Access

Embedded within Test 1 is the assessment of lexical judgment, a language metric sensitive to frontotemporal linguistic erosion. In individuals with ALS, language dysfunction frequently mirrors the non-fluent or semantic variants of primary progressive aphasia (PPA). The lexical decision paradigm requires patients to differentiate real words from phonologically plausible non-words or semantic distractors. This process assesses the integrity of the mental lexicon, the ventral auditory language pathway, and the left perisylvian network without requiring extensive written or oral composition.

3. Verbal Short-Term Memory and Working Memory Span

Central to Test 2 is the evaluation of verbal storage capacity and dynamic cognitive manipulation. In accordance with classical working memory models, the maintenance of verbal sequences under interference conditions demands not only passive maintenance in the short-term phonological buffer but also continuous oversight by the central executive. ALS pathology characteristically compromises working memory through the degradation of dorsolateral prefrontal cortical networks. The CABLET tracks the upper limits of the patient’s span threshold using a tailored adaptive sequence tracking paradigm that captures span degradation.

4. Semantic Knowledge and Executive Manipulation

The advanced sequence tasks within Test 2 interweave executive control with semantic category operations. Unlike passive digit span tasks, the executive manipulation of words requires the patient to hold linguistic information active in memory while organizing, sorting, or classifying terms based on abstract semantic rules. This recruits frontostriatal loops responsible for inhibitory control, cognitive set shifting, and rule-guided category retrieval. By synthesizing semantic classification within an active memory span paradigm, the construct specifically indexes the executive-language interface characteristic of prefrontal and anterior temporal degeneration.

Theoretical Framework

The theoretical framework guiding the design of the CABLET is rooted in contemporary cognitive neuropsychology, Baddeley’s multi-component model of working memory, and the clinicopathological model of Frontotemporal Lobar Degeneration (FTLD).

From a neuropathological perspective, ALS is characterized by the prion-like propagation of hyperphosphorylated, ubiquitinated 43-kDa TAR DNA-binding protein (TDP-43) aggregates. In accordance with the staging system formulated by Brettschneider and colleagues, TDP-43 pathology originates in the agranular motor cortex and the somatomotor nuclei of the brainstem and spinal cord (Stage 1), cascades into the prefrontal neocortex, primary sensory cortices, and the striatum (Stage 2), subsequently reaches the prefrontal and anterior cingulate cortices alongside the postcentral sensory areas (Stage 3), and ultimately invades anteromedial temporal structures including the hippocampus (Stage 4). Cognitive manifestations in ALS precisely track this pathological progression: executive dysfunction, cognitive inertia, and linguistic retrieval deficits emerge early due to Stage 2 and Stage 3 prefrontal-subcortical disruption, whereas classical episodic memory loss and visuospatial disorientation remain absent until advanced Stage 4 involvement.

Drawing on Alan Baddeley’s working memory model, cognitive efficiency depends upon the coordinated interaction between domain-specific slave systems—most notably the phonological loop and the visuospatial sketchpad—and a domain-general central executive system housed within the prefrontal cortex. The central executive governs attentional allocation, selective inhibition, task-switching, and strategic retrieval from long-term memory. In ALS, the central executive shows early vulnerability, rendering complex tasks requiring simultaneous storage and mental manipulation disproportionately impaired compared to simple rote retention.

Crucially, the theoretical framework incorporates the consensus diagnostic criteria established by the Second International Research Group on ALS and FTD (Strong et al., 2017). Under these criteria, neurocognitive compromise in ALS is explicitly dichotomized into:

• ALS-Specific Deficits: Executive dysfunction (impaired planning, set-shifting, working memory, inhibitory control), language dysfunction (loss of semantic access, syntax breakdown, phonemic fluency deficits), and social cognitive alterations.
• ALS-Nonspecific Deficits: Visuospatial processing deficits and isolated episodic memory impairment, which are typically indicative of comorbid neurodegenerative conditions (such as Alzheimer’s disease) or severe global terminal-stage decline.

By restricting its operational domain strictly to auditory-verbal processing, working memory, and semantic executive operations, the CABLET aligns with this theoretical bifurcation. It maximizes diagnostic specificity by isolating ALS-specific cognitive markers while minimizing noise generated by motor disability or irrelevant cognitive domains.

Validity

The psychometric validity of the CABLET was rigorously evaluated in the original validation study by Ohdake et al. (2023), which enrolled a well-characterized cohort of ALS patients alongside demographically matched healthy controls. The investigation concentrated on diagnostic criterion validity, receiver operating characteristic metrics, and cross-domain convergent and discriminant validity.

Diagnostic Sensitivity and Specificity (ROC Analysis)

The diagnostic utility of the CABLET in separating ALS patients with cognitive impairment from cognitively intact patients was examined using Receiver Operating Characteristic (ROC) curves. The diagnostic performance metrics demonstrated high accuracy:

• Total Score Diagnostic Accuracy: The Area Under the Curve (AUC) for the overall CABLET total score was 0.894, indicating high discrimination between cognitively intact and cognitively impaired ALS cohorts.
• Test 2 Performance: Test 2 independently achieved an AUC of 0.893. Diagnostic cutoff modeling indicated that Test 2 delivered an extraordinary sensitivity of 100% alongside a specificity of 71.4%. This indicates that Test 2 functions exceptionally well as a rapid screening measure, avoiding false-negative classifications.
• Robustness Across Covariates: To confirm that diagnostic accuracy was not driven by non-cognitive factors, ROC comparisons were calculated both with and without the inclusion of age, educational attainment, and physical disease severity (measured via the revised ALS Functional Rating Scale, ALSFRS-R) as covariates. No statistically significant variations in the AUC metrics were observed, confirming that the CABLET indexes genuine cognitive impairment rather than functional physical decline or demographic variance.

Convergent Validity

Convergent validity was established by comparing CABLET metrics against comprehensive neuropsychological battery composite scores specifically evaluating ALS-related cognitive domains. Composite z-scores combining standardized measures of executive function and language demonstrated substantial and statistically significant positive correlations with the CABLET:

• CABLET Total Score vs. ALS-specific Composite: r = 0.630 (p < 0.001)
• CABLET Test 2 Score vs. ALS-specific Composite: r = 0.645 (p < 0.001)

These findings substantiate that performance across the CABLET directly reflects deterioration within prefrontal and language networks specifically susceptible to ALS pathology.

Discriminant Validity

Discriminant validity was established by examining the relationships between CABLET performance and neuropsychological domains traditionally categorized as ALS-nonspecific. Composite z-scores summarizing visuospatial ability and non-verbal episodic memory failed to reach statistical correlation with CABLET performance:

• CABLET Total Score vs. ALS-nonspecific Composite: r = 0.168 (p = 0.208)
• CABLET Test 2 Score vs. ALS-nonspecific Composite: r = 0.166 (p = 0.213)

The absence of significant association with visuospatial and primary memory indices provides clear empirical evidence that the CABLET selectively captures frontotemporal and linguistic dysfunction without confounding from other cognitive modalities.

Reliability

Within the initial psychometric validation reported by Ohdake et al. (2023), primary empirical emphasis was directed toward establishing diagnostic sensitivity, specificity, and structural validity against external neurocognitive composites. Consequently, traditional internal consistency coefficients—such as Cronbach’s alpha or McDonald’s omega—were not formally published in the foundational pilot trial.

The omission of standard internal consistency metrics is common during the early-stage development of adaptive cognitive tests. Because Test 2 utilizes an adaptive, branch-dependent sequence algorithm (where progression or regression is contingent upon immediate trial accuracy), individual items are not administered uniformly to all participants. Classical true-score models assume identical item exposure across all examinees; applying traditional item-intercorrelation models to branched adaptive spans violates these foundational assumptions and can produce artificially distorted internal consistency coefficients.

Furthermore, formal test-retest reliability statistics were not reported in the primary pilot cohort due to the rapid physical deterioration inherent to ALS. Longitudinal stability analyses in neurodegenerative populations present significant methodological challenges: short retest intervals risk substantial practice effects in auditory span tasks, while longer intervals conflate psychometric instability with real neurodegenerative progression. Although the initial diagnostic stability is indirectly supported by the robust covariate-controlled AUC metrics (AUC > 0.89), ongoing and future validation trials must formally establish inter-rater concordance across multiple examiners, alternate-form reliability to support serial assessments, and short-term test-retest reliability in clinically stable patient subsets.

Factor Analysis

In the primary publication of the CABLET (Ohdake et al., 2023), formal statistical factor analyses—including Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA)—were not reported. The pilot nature of the study, coupled with the modest sample sizes common to specialized neuromuscular cohorts, precluded the multi-parameter modeling necessary to conduct robust structural equation modeling without introducing statistical overfitting.

Nonetheless, the structural architecture of the CABLET is grounded in a theoretically defined two-factor latent framework:

• Latent Factor 1: Receptive Phonological Integrity & Lexical Verification (Test 1). This component reflects early-stage acoustic phonological decoding, speech-motor execution, and semantic lexicon discrimination. Rather than behaving as a continuous dimensional variable across severe impairment ranges, this factor operates primarily as a low-variance ceiling task for intact individuals and as a qualitative threshold for dysarthric or aphasic individuals.
• Latent Factor 2: Executive-Working Memory & Semantic Organization (Test 2). This dimension accounts for the majority of the variance separating cognitively impaired from non-impaired ALS patients. The adaptive span paradigm taps directly into central executive capacity, attentional tracking, and semantic manipulation.

Future large-scale, multi-center investigations utilizing item response theory (IRT) and structural equation modeling will be valuable to formally confirm this two-factor model, verify unidimensionality within Test 2, and evaluate potential differential item functioning (DIF) across different languages, age brackets, and ALS clinical phenotypes.

Instrument / Measurement Tool

The CABLET is an examiner-administered neuropsychological assessment designed for bedside or clinical evaluation. Key operational characteristics include:

• Test Type: Original performance-based cognitive screening instrument focusing on receptive auditory language and executive working memory.
• Response Format: The test is administered using paper.
• Language Available: Japanese (original validation). Adaptations into other languages require careful phonological and semantic standardization.
• Target Population: Adult human populations (18 years and older; middle-aged 40–64 years; elderly 65+ years) diagnosed with Amyotrophic Lateral Sclerosis across all disease stages, as well as allied motor neuron syndromes where physical disability impedes conventional cognitive testing.
• Administration Structure:
  • Test 1: Word Repetition and Lexical Judgment
    • Purpose: Assesses basic auditory-verbal transmission, speech output capability, and lexical identification. Also functions as a clinical safety gate.
    • Scoring & Cutoff Rule: Maximum score is 32 points. If a participant scores 4 points or less on the word repetition subtask, they are deemed clinically inappropriate to proceed to Test 2 due to profound receptive/motor-articulatory failure.
    • Administration Time: Rapid, requiring approximately 1 minute.
  • Test 2: Verbal Short-Term Memory and Semantic Knowledge
    • Purpose: Assesses verbal working memory span and semantic classification under executive control.
    • Adaptive Span Paradigm: Across all sequence patterns, the examiner initiates testing at a 7-span task to rapidly detect executive-memory impairment.
    • Progression/Regression Rules: For a given sequence pattern, if the participant answers correctly on either of two trials, they advance to a longer span task (8 spans); if the participant is correct on the very first trial, the second trial for that span length is omitted. If the participant fails both trials at the 7-span level, the examiner immediately drops to a shorter span task (6 spans).
    • Sequencing: Participants proceed to subsequent sequence patterns only after completely finishing the adaptive 7-span branch rules for each specific pattern.
    • Scoring Logic: The final successfully mastered span length for each sequence pattern represents the score for that pattern. If a participant fails the minimum baseline threshold of the 4-span task across both trials, a score of 0 points is assigned for that pattern.
    • Maximum Score: Test 2 yields a maximum of 40 points.
  • Total Score Calculation: The global CABLET score is the sum of Test 1 and Test 2, yielding a maximum possible score of 72 points.

Permissions & Fee and Test Year

• Test Year of Publication: 2023.
• Intellectual Property & Permissions: The instrument is intellectual property developed by the original authors (Ohdake et al., 2023). The test materials are not published in the open public domain to preserve psychometric security and prevent uncontrolled patient pre-exposure. Researchers and clinicians wishing to use the official test protocols, manual, and scoring sheets must contact the corresponding author: Hirohisa Watanabe, MD, PhD, Department of Neurology, School of Medicine, Fujita Health University, Toyoake, Aichi, Japan (Email: [email protected]).
• Fee: No licensing fee is charged (free of charge for academic, non-commercial research and clinical diagnostic screening, subject to author approval).

References

• Baddeley, A. (2000). The episodic buffer: A new component of working memory? Trends in Cognitive Sciences, 4(11), 417–423. https://doi.org/10.1016/S1364-6613(00)01538-2
• Brettschneider, J., Del Tredici, K., Toledo, J. B., Robinson, J. L., Irwin, D. J., Grossman, M., Suh, E., Van Deerlin, V. M., Wood, E. M., Baek, Y., Kwong, L., Lee, E. B., Elman, L., McCluskey, L., Fang, L., Feldengut, S., Ludolph, A. C., Lee, V. M., & Trojanowski, J. Q. (2013). Stages of pTDP-43 pathology in amyotrophic lateral sclerosis. Annals of Neurology, 74(1), 20–38. https://doi.org/10.1002/ana.23937
• Ohdake, R., Watanabe, H., Kawabata, K., Ogura, A., Sato, M., Tanaka, Y., Imai, K., Masuda, M., Kato, T., Yokoi, T., Hara, K., Nakamura, R., Atsuta, N., Nakagawa, M., Katsuno, M., & Sobue, G. (2023). Convenient auditory-based language and executive function test for patients with amyotrophic lateral sclerosis: A pilot study. Archives of Clinical Neuropsychology, 38(1), 57–71. https://doi.org/10.1093/arclin/acac069
• Strong, M. J., Abrahams, S., Goldstein, L. H., Woolley, S., Mclaughlin, P., Snowden, J., Mioshi, E., Roberts-South, A., Benatar, M., Hortobágyi, T., Rosenfeld, J., Silani, V., Ince, P. G., & Turner, M. R. (2017). Amyotrophic lateral sclerosis – frontotemporal spectrum disorder (ALS-FTSD): Revised diagnostic criteria. Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration, 18(3–4), 153–174. https://doi.org/10.1080/21678421.2016.1267760

Items of the Scale