The efficacy of a centrally active cholinesterase inhibitor, rivastigmine tartrate (ENA 713), in patients with advanced moderate Alzheimer's disease ( AD) was evaluated in a 12-month placebo-controlled study. We aimed to investigate whether there was any evidence for the benefits of rivastigmine in patients with severe disease. These patients were compared with matched controls. In this study, 24 patients with advanced moderate AD received rivastigmine for 12 months. Another 20 patients received placebo. Mean daily doses of rivastigmine in the higher-dose group at 3, 6, 9, and 12 months were 6.1 +/- 1.0, 8.3 +/- 1.2, 8.9 +/- 1.3, and 10.7 +/- 1.6 mg/day, respectively. Cognitive abilities were assessed using the 11-item cognitive subscale of the Alzheimer Disease Assessment Scale (ADAS-cog). Forty-five percent of placebo-treated patients declined by at least 4 points on the ADAS-cog. Conversely, only 18.3% of patients treated with rivastigmine declined by 4 or more points. Functional disabilities, as assessed using the Disability Assessment for Dementia Scale, remained significantly superior in rivastigmine-treated patients compared with placebo-treated patients. Patients benefited from high-dose rivastigmine treatment on all outcome measures, including the Mini-Mental State Examination, Progressive Deterioration Scale, as well as the Global Deterioration Scale. Patients receiving rivastigmine for 12 months significantly improved compared with placebo-treated patients (p < 0.001). By 52 weeks, patients originally treated with 6-12 mg/day rivastigmine had a significantly better cognitive function than patients originally treated with placebo. Long-term rivastigmine treatment appeared to be well tolerated in patients with advanced moderate AD and significantly benefits the cognitive and functional symptoms of AD. Copyright (C) 2005 S. Karger AG, Basel.