Cross-national comparison and validation of the Alzheimer's Disease Assessment Scale: results from the European Harmonization Project for Instruments in Dementia (EURO-HARPID).

Background: The Alzheimer's Disease Assessment Scale (ADAS) is often used in international multicenter trials. Use across countries presupposes correct translation and adaptation of the scale, and maintenance of its psychometric properties.

Objectives: To compare the various translations of the ADAS used in Western Europe, to design internationally harmonized translations and to validate these.