Functional disability in early Alzheimer's disease - a validation study of the Italian version of the disability assessment for dementia scale.

AIM: To determine the applicability and psychometric properties of the Italian version of the Disability Assessment of Dementia scale (DAD-I) in a community-residing population with early-stage Alzheimer's disease (AD). METHODS: The DAD-I was administered to the primary caregivers of 159 patients (mean age +/- SD 77.1 +/- 5.2) with mild AD (mean Mini Mental State Examination, MMSE, +/- SD 23.1 +/- 2.2). RESULTS: The DAD-I showed excellent internal consistency reliability (Cronbach's alpha = 0.92) and good construct validity. The DAD-I score was not significantly associated with gender, education and presumed duration of the illness, and had a low negative correlation with age. The DAD-I score correlated moderately with the traditional Instrumental Activities of Daily Living and Activities of Daily Living scales, respectively, with r = 0.53 and r = 0.54 (p < 0.0001). Relatively low, but statistically significant correlations (r ranging between 0.21 and 0.31) with the MMSE were also found. CONCLUSION: The DAD-I was found to be a reliable and valid instrument to assess functional disability in community-dwelling Italian subjects with early-stage AD.