Development and initial psychometric properties of the Warwick-Edinburgh Mental Wellbeing Scale-Intellectual Disability version

BACKGROUND

The Warwick-Edinburgh Mental Wellbeing Scale (WEMWBS; Tennant et al., 2007) is yet to be validated in the intellectual disability (ID) population. The aim of this study was to report the development process and assess the psychometric properties of a newly adapted version of the WEMWBS and the Short WEMWBS for individuals with mild to moderate IDs (WEMWBS-ID/SWEMWBS-ID).

METHOD

The WEMWBS item wordings and response options were revised by clinicians and researchers expert in the field of ID, and a visual aid was added to the scale. The adapted version was reviewed by 10 individuals with IDs. The measure was administered by researchers online using screenshare, to individuals aged 16+ years with mild to moderate IDs. Data from three UK samples were collated to evaluate the WEMWBS-ID (n = 96). A subsample (n = 22) completed the measure again 1 to 2 weeks later to assess test-retest reliability, and 95 participants additionally completed an adapted version of the adapted Rosenberg Self-Esteem Scale to examine convergent validity. Additional data from a Canadian sample (n = 27) were used to evaluate the SWEMWBS-ID (n = 123).

RESULTS

The WEMWBS-ID demonstrated good internal consistency (ω = 0.77-0.87), excellent test-retest reliability [intraclass correlation coefficient (ICC) = .88] and good convergent validity with the self-esteem scale (r = .48-.60) across samples. A confirmatory factor analysis for a single factor model demonstrated an adequate fit. The SWEMWBS-ID showed poor to good internal consistency (ω = 0.36-0.74), moderate test-retest reliability (ICC = .67) and good convergent validity (r = .48-.60) across samples, and a confirmatory factor analysis indicated good model fit for a single factor structure.

CONCLUSIONS

The WEMWBS-ID and short version demonstrated promising psychometric properties, when administered virtually by a researcher. Further exploration of the scales with larger, representative samples is warranted.

Modulation of linguistic prediction by TDCS of the right lateral cerebellum

It has been postulated recently that the cerebellum contributes the same prediction and learning functions to linguistic processing as it does towards motor control. For example, repetitive TMS over posterior-lateral cerebellum caused a significant loss in predictive language processing, as assessed by the latency of saccades to target items of spoken sentences, using the Visual World task. We aimed to assess the polarity-specific effects of cerebellar TDCS, hypothesising that cathodal TDCS should impair linguistic prediction, and anodal TDCS facilitate it. Our design also tested whether TDCS modulated associative learning in this task. A between groups (sham, anodal, cathodal) design was used, with concurrent stimulation during performance of a manual variation of the Visual World paradigm, and with assessment of latency reduction over repeated presentations of the spoken sentences. Mixed model ANOVA was used to analyse change in response latency. Cathodal TDCS decreased participants’ response time advantage for the predictable sentence items without change for non-predictable items, consistent with the previous TMS results. Furthermore, anodal stimulation enhanced the response time advantage for the predictable items, again without change in latencies for non-predictive items. We found a clear practice-based effect over 4 blocks. However, this difference was not significantly modulated by either anodal or cathodal stimulation. Our results therefore support the hypothesis that cerebellum contributes to predictive language processing, mirroring its predictive role in motor control, but we do not yet have evidence that the learning process was affected by cerebellar TDCS.

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Disruption of the lateral cerebellum with TMS impairs prediction in language processing.

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We now report the effect of anodal and cathodal TDCS, and assess short-term learning.

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Cathodal TDCS replicated the TMS effect, reducing linguistic prediction.

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Anodal TDCS reversed the effect, enhancing prediction; neither affected short-term learning.

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This work adds new evidence that the cerebellum contributes to predictive language processing.