Cultural adaptation of Alzheimer’s disease assessment scale–cognitive subscale for use in India and validation of the Tamil version for South Indian population

Abstract

Objective

Currently no standardized tools are available in the Indian languages to assess changes in cognition. Our objectives are to culturally adapt the Alzheimer’s disease Assessment Scale–Cognitive Subscale (ADAS-Cog) for use in India and to validate the Tamil version in an urban Tamil-speaking older adult population.

Methods

Two panels of key stakeholders and a series of qualitative interviews informed the cultural and linguistic adaptation of the ADAS-Cog-Tamil. Issues related to levels of literacy were considered during the adaptation. Validation of the ADAS-Cog-Tamil was completed with 107 participants − 54 cases with a confirmed diagnosis of mild-moderate dementia, and 53 age, gender and education matched controls. Concurrent validity was examined with the Vellore Screening Instrument for Dementia (VSID) in Tamil. Internal consistency using Cronbach’s alpha, sensitivity and specificity data using the Area under the Receiver Operating Characteristics (AUROC) curve values were computed. Inter-rater reliability was established in a subsample.

Results

The ADAS-Cog-Tamil shows good internal consistency (α = 0.91), inter-rater reliability and concurrent validity (with VSID-Patient version: r = –0.84 and with VSID-Caregiver version: r = –0.79). A cut-off score of 13, has a specificity of 89% and sensitivity of 90% for the diagnosis of dementia.

Conclusion

ADAS-Cog-Tamil, derived from a rigorous, replicable linguistic and cultural adaptation process involving service users and experts, shows good psychometric properties despite the limitations of the study. It shows potential for use in clinical settings with urban Tamil speaking populations. The English version of the tool derived from the cultural adaptation process could be used for further linguistic adaptation across South Asia.

Keywords:

• ADAS-Cog
• Tamil
• adaptation
• validation
• dementia
• cognition
• India
• South Asia

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Acknowledgement

We acknowledge the contribution of members of our team and the participants in the expert panels in the conduct of this study.

Author contributions

ML designed the study, conducted literature search, collected data, analysed data, interpreted the results and wrote the first draft of the paper. SV designed the study, interpreted results and edited and finalized the manuscript. NS, GN and AG assisted in literature search, collected and managed the data. Authors KS, MC, MK and AS were involved in designing the study, edited and finalized the manuscript. All authors were involved in preparation of the manuscript read, critically reviewed and approved the final manuscript.

Disclosure statement

Dr. Sridhar Vaitheswaran has received speaker honorarium from Novartis, unrelated to this work. Other authors report no relevant conflict of interest. The authors declare that any part of this work has not been submitted or published elsewhere.

Data sharing

Data available on request from the authors.

Additional information

Funding

This work is supported by the following Global Alliance for Chronic Diseases (GACD) funding agencies: The United Kingdom Medical Research Council (MRC: MR/S004009/1) and the Indian Council of Medical Research (ICMR: Indo-foreign/67/M/2018-NCD-I). The funding bodies GACD, MRC or ICMR had no further role in the study process.