Efficacy of donepezil in mild cognitive impairment: a randomized placebo-controlled trial. Donepezil treatment of patients with MCI: a 48-week randomized, placebo-controlled trial.
To evaluate the efficacy and safety of the acetylcholinesterase inhibitor donepezil in a placebo-controlled trial in patients with mild cognitive impairment (MCI).
                A total of 270 patients with MCI were enrolled in a 24-week, multicenter, randomized, double-blind, placebo-controlled study. Patients were randomized to receive donepezil (n = 133; 5 mg/day for 42 days, followed by forced dose escalation to 10 mg/day) or placebo (n = 137). Primary efficacy measures were the New York University (NYU) Paragraph Delayed Recall test and the Alzheimer disease (AD) Cooperative Study Clinician's Global Impression of Change for MCI (ADCS CGIC-MCI). Secondary efficacy measures included the modified AD Assessment Scale-cognitive subscale (ADAS-cog), the Patient Global Assessment (PGA), and additional neuropsychologic measures. Efficacy analyses were performed on intent-to-treat (ITT) and fully evaluable (FE) populations.
                Primary efficacy measures of the NYU Paragraph Recall test and the ADCS CGIC-MCI did not show significant treatment effects in the ITT population. Some secondary measures showed effects favoring donepezil. More donepezil-treated patients showed improvements in ADAS-cog total scores, in tests of attention and psychomotor speed, and in PGA scores. More donepezil-treated than placebo-treated patients experienced adverse events, most of which were mild to moderate and transient.
                Although significant treatment effects were not seen in the primary efficacy measures, outcomes on secondary measures suggest promising directions for further evaluation of donepezil treatment in patients with MCI. Treatment of mild cognitive impairment (MCI) with cholinesterase inhibitors may improve symptoms.
                In this multicenter, randomized, placebo-controlled trial, subjects with MCI entered a 3-week placebo run-in period followed by 48 weeks of double-blind donepezil (5 mg/day for 6 weeks, then 10 mg/day for 42 weeks) or placebo treatment. Primary efficacy variables included change from baseline in the modified Alzheimer Disease Assessment Scale-cognitive subscale (ADAS-Cog) and Clinical Dementia Rating Scale-sum of boxes (CDR-SB) after 48 weeks of treatment (modified intention-to-treat analysis). Secondary efficacy measures evaluated cognition, behavior, and function.
                The dual primary efficacy endpoint was not reached. We noted a small, but significant, decrease in modified ADAS-Cog scores in favor of donepezil at study endpoint. Little change from baseline in CDR-SB and secondary variables was observed for either group. Patient Global Assessment scores favored donepezil at all time points except week 12 (p < or = 0.05). Perceived Deficits Questionnaire scores favored donepezil at week 24 (p = 0.05). Clinical Global Impression of Change-MCI scores favored donepezil only at week 6 (p = 0.04). Adverse events were generally mild or moderate. More donepezil-treated subjects (18.4%) discontinued treatment due to adverse events than placebo-treated subjects (8.3%).
                Donepezil demonstrated small but significant improvement on the primary measure of cognition but there was no change on the primary measure of global function. Most other measures of global impairment, cognition, and function were not improved, possibly because these measures are insensitive to change in MCI. Responses on subjective measures suggest subjects perceived benefits with donepezil treatment.
There are two included studies which reported results for cognitive function. One study demonstrated a modest treatment effect in cognitive function as assessed by ADAS-Cog13 but not for other outcomes assessing different domains of cognitive function. Donepezil was associated with significantly more adverse effects compared with placebo, mostly gastrointestinal. From the second study, there is no evidence that donepezil delays the onset of AD. There is no evidence to support the use of donepezil for patients with MCI. The putative benefits are minor, short lived and associated with significant side effects.