Background: The Mini-mental State Examination (MMSE) is the most widely used cognitive test, both in clinical settings and in epidemiological studies. However, correcting its score for education may create ceiling effects when used for poorly educated people and floor effects for those with higher education.
Methods: MMSE and a recent cognitive test, the seven minute screen (7MS), were serially administered to a community sample of Mexican elderly. 7MS test scores were equated to MMSE scores. MMSE-equated 7MS differences indicated ceiling or floor effects. An ordinal logistic regression model was fitted to identify predictors of such effects.
Results: Poorly educated persons were more prevalent on the side of MMSE ceiling effects. Concentration (serial-sevens), orientation and memory were the three MMSE subscales showing the strongest relationship to MMSE ceiling effects in the multivariate model.
Conclusion: Even when MMSE scores are corrected for educational level they still have ceiling and floor effects. These effects should be considered when interpreting data from longitudinal studies of cognitive decline. When an education-adjusted MMSE test is used to screen for cognitive impairment, additional testing may be required to rule out the possibility of mild cognitive impairment.