Measuring cognitive change in older adults: reliable change indices for the Mini-Mental State Examination

Background: In clinical and research settings, the Mini-Mental State Examination ( MMSE) is commonly used to measure cognitive change over time. The interpretation of changes in MMSE is often difficult. They do not necessarily result from true clinical change. Their interpretation requires comparison with normative data for change. However, MMSE change norms are lacking for long intervals. Objective: To examine what is a reliable change in MMSE for long follow-up periods commonly used in clinic. To provide normative data for change. Methods: A sample of 119 cognitively normal individuals, aged 75 years and over, who participated in the Leipzig Longitudinal Study of the Aged ( LEILA 75+). All participants were tested six times at 1.5 year intervals with the MMSE over a mean period of 7.1 years. Reliable change indices were computed for a common confidence interval (90%). Results: In repeated assessments with 1.5 year intervals, a change in MMSE of at least 2-4 points indicated a reliable change at the 90% confidence level. Conclusion: Small changes in MMSE can be interpreted only with great uncertainty. They have a reasonable probability of being caused by measurement error, regression to the mean or practice.