Neither vitamin E nor donepezil delays progression from amnestic mild cognitive impairment to Alzheimer's disease in the long term.

MAIN RESULTS Compared with placebo, neither vitamin E nor donepezil altered the probability of progression to Alzheimer’s disease after three years (vitamin E v placebo: HR for progression 1.02, 95% CI 0.74 to 1.41; donepezil v placebo: HR for progression 0.80, 95% CI 0.57 to 1.13). However, there was some indication that donepezil slowed progression to Alzheimer’s disease over the first two years compared with placebo (p = 0.03). Donepezil increased adverse events compared with placebo (diarrhoea, muscle cramps, insomnia, nausea, abnormal dreams: p,0.01; loose stools, vomiting, arthritis: p,0.05).