The rate of cognitive decline and risk of reaching clinical milestones in Alzheimer disease

Background: Previous studies revealed that cognitive test scores were related to functional outcome in Alzheimer disease (AD). However, the relationship between the rate of cognitive decline at the initial disease phase and the risk of reaching clinical milestones in subsequent years has not yet been examined. Objective: To examine whether the rate of cognitive decline predicts the risk of reaching functional milestones in patients with probable AD. Design: A 5-year prospective study was conducted at 3 sites. Setting: Outpatient research and treatment centers. Participants: Patients diagnosed with probable AD (N = 236; mean age, 73 years; 59% women; mean years of education, 13). Main Outcome Measures: Modified Mini-Mental State Examination (mMMSE) scores were used to assess the rate of cognitive decline over time. Total dependence score and 2 clinical milestones: (1) the need to be dressed, groomed, and washed and (2) receiving a level of care equivalent to a placement in a health-related facility, were derived from the Dependence Scale. Results: General estimating equation analyses revealed that the rate of cognitive decline during the entire follow-up period was positively related to an increase in total dependence scores. Cox analyses showed that a fast rate of decline during the first year was related to an increase in the risk of reaching clinical milestones in subsequent years. Analyses controlled for age, sex, education, and baseline mMMSE scores. Conclusion: A fast rate of cognitive decline was associated with increasing risk of reaching clinical milestones in AD.