Long-term benefits of rivastigmine in dementia associated with Parkinson's disease: an active treatment extension study.

In patients with dementia associated with Parkinson's disease (PD), the efficacy and safety of rivastigmine, an inhibitor of acetylcholinesterase and butyrylcholinesterase, were previously demonstrated in a 24-week double-blind placebo-controlled trial. Our objective was to determine whether benefits were sustained over the long term. Following the double-blind trial, all patients were permitted to enter an active treatment extension study, during which they received rivastigmine 3-12 mg/day. Standard safety assessments were performed. Efficacy assessments included the Alzheimer's Disease Assessment Scale cognitive subscale (ADAS-cog) and other measures of cognition, daily function, neuropsychiatric symptoms, and executive function. Of 433 patients who completed the double-blind trial, 334 entered and 273 completed the active treatment extension. At 48 weeks, the mean ADAS-cog score for the whole group improved by 2 points above baseline. Placebo patients switching to rivastigmine for the active treatment extension experienced a mean cognitive improvement similar to that of the original rivastigmine group during the double-blind trial. The adverse event profile was comparable to that seen in the double-blind trial. Long-term rivastigmine treatment appeared well tolerated and may provide sustained benefits in dementia associated with PD patients who remain on treatment for up to 48 weeks.