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.