Folstein, M. F., Folstein, S. E., & McHugh, P. R. (1975). "Mini-mental state": 
a practical method for grading the cognitive state of patients for the clinician. 
Journal of psychiatric research, 12(3), 189-198.

Abstract
The Mini-Mental State (MMS) is a short standardized form devised for the serial 
testing of the cognitive mental state in patients on a neurogeriatric ward, 
as well as for consecutive admission to a hospital. The MMS was found to be quick 
(5-10 min to administer), easy to use (11 questions), and acceptable to patients and 
testers. When given to 69 patients with dementia, depression with cognitive impairment, 
and depression (Sample A), the test proved to be valid and reliable. It was able
to separate the 3 diagnostic groups, it reflected clinical cognitive change, it 
did not change in patients thought to be cognitively stable, and it was correlated 
with the WAIS scores. Standardization of the test by administration to 63 normal 
elderly Ss and 137 patients (Sample B) indicated that the score of 20 or less was 
found essentially only in patients with dementia, delirium, schizophrenia, or 
affective  disorder, but not in normal elderly people or in patients with a primary 
diagnosis of neurosis and personality disorder. The MMS was useful in quantitatively 
estimating the severity of cognitive impairment, in serially documenting cognitive 
change, and in teaching residents a method of cognitive assessment.