The Japanese Translation Study of the Cognitive Reserve Index Questionnaire.

BACKGROUND: The cognitive reserve index questionnaire (CRIq) is widely used to quantify cognitive reserve (CR), but a validated Japanese version is lacking. This study aimed to translate and culturally adapt the CRIq and its short version (s-CRIq) into Japanese (CRIq-J and sCRIq-J) and to evaluate their reliability and criterion-related validity. METHODS: Following international guidelines for cultural adaptation and translation, we translated and culturally adapted the CRIq and s-CRIq into Japanese. The study participants were 3567 community-dwelling Japanese older adults from a large-scale cohort. Global cognitive performance was assessed with the composite score of the National Center for Geriatrics and Gerontology-Functional Assessment Tool and global cognitive impairment (GCI) was defined as a mini-mental state examination score ≤ 23. Internal consistency was assessed using Cronbach's alpha. Multiple and logistic regression analyses were performed to examine associations between CRIq-J and sCRIq-J total scores and global cognitive performance, including GCI. RESULTS: Cronbach's alpha coefficients were 0.58 for the CRIq-J and 0.48 for the sCRIq-J, reflecting the multidimensional nature of life-course experiences. After adjusting for age and sex, higher scores on both the CRIq-J (β = 0.21, 95% CI: 0.18-0.24, p < 0.001) and sCRIq-J (β = 0.21, 95% CI: 0.17-0.25, p < 0.001) were significantly associated with superior cognitive performance. Furthermore, higher CRI levels were associated with a significantly lower likelihood of GCI. CONCLUSIONS: The CRIq-J and sCRIq-J demonstrated acceptable reliability and robust criterion-related validity in a Japanese population. These standardized tools represent a significant milestone for future CR research and the development of dementia prevention strategies in Japan.