Limitations of the Mini-Mental State Examination
The Mini-Mental State (MMS) Examination is perhaps the most frequently used bedside screening measure of cognition of psychiatric and neurologic patients. It represents a formal, more standardized qualitative approach to determining mental status than an unstructured interview. Initial validation efforts comparing MMS scores of psychiatric patients to the results of more informal mental status interviews were very encouraging. Subsequent research comparing the scale to other criteria has suggested some limitations of its use, however. It has been found to overestimate impairments in persons over age 60 and in persons with less than nine years of education. The MMS scale has been reported to be insensitive to cognitive impairments resulting from right hemisphere dysfunction as well as milder forms of cognitive dysfunction irrespective of cortical origin. Case studies that demonstrate its inaccuracy in identifying cognitive impairments in individuals with average and low-average verbal IQs are reviewed. These limitations have far-reaching implications for both research and clinical applications of the measure. Proper use of the MMS requires that the user be aware of instances when the scale is likely to produce misleading data.