Population-based norms for the Mini-Mental State Examination by age and educational level.

OBJECTIVE To report the distribution of Mini-Mental State Examination (MMSE) scores by age and educational level. DESIGN National Institute of Mental Health Epidemiologic Catchment Area Program surveys conducted between 1980 and 1984. SETTING Community populations in New Haven, Conn; Baltimore, Md; St Louis, Mo; Durham, NC; and Los Angeles, Calif. PARTICIPANTS A total of 18,056 adult participants selected by probability sampling within census tracts and households. MAIN OUTCOME MEASURES Summary scores for the MMSE are given in the form of mean, median, and percentile distributions specific for age and educational level. RESULTS The MMSE scores were related to both age and educational level. There was an inverse relationship between MMSE scores and age, ranging from a median of 29 for those 18 to 24 years of age, to 25 for individuals 80 years of age and older. The median MMSE score was 29 for individuals with at least 9 years of schooling, 26 for those with 5 to 8 years of schooling, and 22 for those with 0 to 4 years of schooling. CONCLUSIONS Cognitive performance as measured by the MMSE varies within the population by age and education. The cause of this variation has yet to be determined. Mini-Mental State Examination scores should be used to identify current cognitive difficulties and not to make formal diagnoses. The results presented should prove to be useful to clinicians who wish to compare an individual patient's MMSE scores with a population reference group and to researchers making plans for new studies in which cognitive status is a variable of interest.