Behavioral evaluation of Alzheimer disease in clinical trials: development of the Japanese version of the GBS Scale.

GBS scale with four subscales and 26 total items is a behavior rating scale for dementia syndromes, and is now being used as one of the measures to assess the effects of drug therapy in dementia in Japan. In this article, the reliability and validity of the Japanese version of GBS Scale (GBSS-J) in 246 patients with dementia are examined. Two pairs of raters independently rated 20 patients to test inter-rater reliability of the 26 items. Pearson's correlation coefficients indicated good agreement between the raters except for nine items. The validity of the 26 items was examined by comparing them with the Functional Assessment Staging. Physical disability was evaluated by the Rapid Disability Rating Scale. Twenty items of GBSS-J measured the severity of dementia with sufficient validity. In addition, the items of eating, impaired physical activity, impaired wakefulness, and irritability were related to severity of physical disability rather than to dementia by the results from an analysis of variance and covariance. Although internal reliabilities by Cronbach's alpha of the three subscales were relatively high except for the subscale of different symptoms common in dementia, a factor analysis of the 26 items raised questions concerning the construct validity of the original four subscales.