BACKGROUND/OBJECTIVE: There is insufficient evidence to guide decisions concerning how long anti-dementia drug (ADD) regimens should be maintained in severe Alzheimer's disease (AD). We investigated whether patients with extremely severe AD who were already receiving donepezil or memantine benefited from continuing treatment.

METHODS: In this randomized and rater-blinded trial, 65 AD patients with a Mini-Mental State Examination score from 0 to 5 and a score of 6c or worse on Functional Assessment Staging were randomly assigned to an ADD-continuation group (N = 30) or an ADD-discontinuation group (N = 35). The current use of donepezil or memantine was maintained for 12 weeks in the ADD-continuation group and was discontinued after baseline in the ADD-discontinuation group. Efficacy measures were obtained at baseline and 12 weeks. The primary efficacy variable was the change from baseline to the end of the study in Baylor Profound Mental State Examination (BPMSE) scores.

RESULTS: The change in the BPMSE from baseline to the end of the study in the ADD-continuation group (a 0.4-point improvement) was not equivalent to that in the ADD-discontinuation group (a 0.5-point decline), as determined by two one-sided tests of equivalence. Study withdrawals due to adverse events (11.4% versus 6.7%) were more frequent in the ADD-discontinuation group than in the ADD-continuation group.

CONCLUSION: Continued treatment with donepezil or memantine seems unequal and might be superior to withdrawal of the drugs in terms of the effects on global cognition in patients with extremely severe AD. Current Controlled Trials number: KCT0000874 (CRIS).