The study consisted of a screening period (up to 2-week period from screening to randomization), a 24-week double-blind treatment period with placebo or idalopirdine 60mg/day as adjunctive therapy to an acetylcholinesterase inhibitor (donepezil 10mg/day, rivastigmine at the patient's individual maintenance dose, or galantamine at the patient's individual maintenance dose), and a 4-week safety follow-up period following study completion or withdrawal from treatment. The dose could be decreased once during the study to 30mg/day if 60mg/day was not well tolerated in the opinion of the investigator. The dose could be increased again to 60mg/day, after which the dose was kept fixed for the remainder of the study. Dose changes were permitted until Week 12 (Visit 5).
