Natural History of Functional Decline in Alzheimer's Disease: A Systematic Review

Background: Knowledge of functional evolution in dementia is crucial for the patients and their families as well as the clinician. Objective: This review identifies scales and outcomes used to describe the natural history of functional decline and describes the natural history of functional decline in a representative clinical population sample of published studies of patients with Alzheimer's disease (AD). Methods: A search of three relevant databases was conducted and limited to articles published in English and French between 1998 to March 2012, using the keywords Dementia, Activities of Daily Living, Instrumental Activities of Daily Living, Functional Impairment, Prognosis, and Disease Progression. Results: The search strategy displayed 683 articles, 20 of which were found to be related to the functional evolution of AD. In these studies, different scales were used to describe the evolution of the functional decline, except for the decline of instrumental activities, for which the Lawton scale was used in all studies. Thus, it is difficult to represent the evolution of the functional decline from a clinical point of view. Conclusion: Relatively little data are available to estimate the functional evolution of AD. A consensus with broadened thought is required to know if the progression of the incapacities in these scales is additive or hierarchical.