Despite a rapid increase in disabled elderly in Japan, the burden of the caregiver has not been properly assessed due to a lack of objective measurements. Our study was aimed at adapting and validating the Zarit Caregiver Burden Interview (ZBI) in Japan, which is one of the most widely used measurements for caregivers' burden in the United States. Sixty-six caregivers answered the self-administered questionnaire, involving the Japanese version of the ZBI and questions regarding their caregiving situation. Our study demonstrated that the Japanese version of the ZBI had equally as high reliability and validity as the original version. The Japanese ZBI had a high test-retest reliability (r = 0.76) and internal consistency (Cronbach's alpha = 0.93). The total score of the ZBI was highly correlated with the caregivers' score of the Center for Epidemiologic Studies Depression Scale (CES-D) score (r = 0.50), as well as a single global rating of burden (r = 0.71). It was also shown that demographic distribution of the score of the Japanese version had a similar trend to that of the original version. Caregivers who looked after patients with behavioral disturbances were found to have a significantly higher ZBI score than those who looked after patients without behavioral disturbances, which is consistent with previous findings. It is concluded that the Japanese version of the ZBI can be used to measure feelings of burden of caregivers in the Japanese population and can be used for cross-cultural comparison.
