The Disability Assessment for Dementia (DAD) scale was developed and validated as a measure of functional ability in dementia. DAD results have been reported in Alzheimer disease (AD) randomized, controlled treatment trials of up to 6 months, but results beyond 6 months have yet to be described. SAB INT 12 was a randomized, double-blind, placebo-controlled, parallel-group study in mild to moderate AD that included DAD assessments at baseline, month 6, and month 12. One hundred forty-four patients with AD in the placebo arm of SAB INT 12 were followed up for 12 months. DAD scores were obtained at baseline (mean DAD = 70.1, SD = 22.2), 6 months (mean DAD = 63.7, SD = 25.2), and 12 months (mean DAD = 59.3, SD = 28.9). The rate of decline was consistent across the domains of basic activities of daily living (ADLs) and instrumental ADLs, as well as the scoring of initiation, planning, and organization. The decline in DAD total scores in mild to moderate AD averages about one point per month, which equates to the loss of one item on the DAD scale every 2 months.