Predictive value of rapid decline in mini mental state examination in clinical practice for prognosis in Alzheimer's disease

Background: Given the poorer prognosis of Alzheimer's disease (AD) patients with rapid cognitive decline (RCD), there is a need for a clinical assessment tool to detect these patients. Objective: To investigate if there is a Mini Mental State Examination (MMSE) threshold of decline during 6 months of follow-up which predicts a worse disease progression at the 2-year follow-up. Then, to propose a feasible definition of RCD for routine clinical practice. Methods: Data from 565 community-dwelling AD patients recruited in a multi-centre prospective observational study were assessed. All patients had MMSE scores between 10 and 26 at inclusion and were followed up 6-monthly using a standardised clinical assessment. Patients were classified as rapid and non-rapid decliners according to 2 MMSE decline thresholds tested: >= 3 points and >= 4 points for decline over the first 6 months of the study. Worse disease outcome was defined as attainment of 1 of 4 clinical end points 18 months later: institutionalisation, death, increased physical dependence or worsening of behavioural and psychological symptoms. Results: 135 patients (23.9%) lost >= 3 points during the first 6 months of follow-up in the MMSE score and 77 patients (13.6%) lost >= 4 points. Patients with moderate disease and a loss of >= 4 points showed a significantly increased risk of mortality (HR = 5.6, 95% CI 2.0-15.9) and institutionalisation (HR = 3.8, 95% CI 1.8-8.1) at the 2-year follow-up. The same MMSE threshold was associated with a higher risk of physical decline (HR = 1.6, 95% CI 1.2-2.3). Conclusion: The loss of >= 4 points in MMSE during the first 6 months of follow-up seems to be a predictor of worse clinical course, and thus it could be used to define the category of AD patients presenting a RCD. Copyright (C) 2008 S. Karger AG, Basel.