Rivastigmine in the treatment of delirium in older people: a pilot study

Background: Delirium is common in the elderly and is associated with high mortality and negative health outcomes. Reduced activity in the cholinergic system has been implicated in the pathogenesis of delirium. Cholinesterase inhibitors, which increase cholinergic activity, may therefore be beneficial in the treatment of delirium. Methods: This is a double-blind, placebo-controlled randomized pilot study of the treatment of delirium with a cholinesterase inhibitor of patients admitted to hospital medical wards. Patients over the age of 65 years were identified as having delirium by the Confusion Assessment Method (CAM). Patients with delirium were randomized to receive rivastigmine 1.5 mg once a day increasing to 1.5 mg twice a day after seven days or an identical placebo (two tablets after seven days). Results: Fifteen patients entered the trial; eight received rivastigmine and seven received placebo. All of the rivastigmine group, but only three of the placebo group, were negative for delirium on the CAM when they left the study and eventually discharged home. There was no significant difference in the duration of delirium between the two groups (rivastigmine group 6.3 days versus placebo group 9.9 days, p = 0.5, 95% confidence interval -15.6-8.4). Conclusions: The numbers of patients who screened positive for delirium was very small and as a result the sample size was too small to make any meaningful inferences about treatment of delirium. Despite the small numbers included in the study, there are some indicators that rivastigmine may be safe and effective in treating delirium.