Cognition and function in Alzheimer's disease: identifying the transitions from moderate to severe disease

Cognitive and functional decline define the transition from moderate to severe Alzheimer's disease (AD); however, specific relationships between deteriorating cognition and functional abilities are less well characterized. Such relationships are important in care planning and understanding patient needs. Objectives of this post hoc analysis of data from a multicenter randomized double-blind placebo-controlled study were to describe changes in Severe Impairment Battery (SIB) scores over 6 months in patients with moderate to severe AD (MSAD), including an assessment of donepezil treatment on SIB scores, and to potentially identify a cognitive transition point associated with predicted functional disability.

The study comprised 290 patients with MSAD (standardized Mini-Mental State Examination score, 5-17) treated with donepezil 5-10 mg/day or matching placebo. Measurements were SIB, Functional Rating Scale, and Disability Assessment for Dementia.

The largest decline in ability to perform basic activities of daily living (bADLs) occurred in placebo-treated patients with a baseline SIB score of approximately 70. Changes were reduced in the donepezil-treated group.

This post hoc exploratory analysis suggests that a transition point between moderate and severe AD exists at a SIB score of approximately 70 and is associated with predictably declining bADLs.