Limitations of the Mini-Mental Status Examination
The Mini-Mental Status Examination (MMSE) is a quantitative measure of cognitive status in adults. Since its creation in 1975, the MMSE has become the most widely used standardized cognitive screening test in both clinical practice and research.
As a screening tool, the MMSE can have limitations, some of which are outlined here:
· Interestingly, the MMSE was never actually designed for diagnosis of dementia; rather it was to be used as ‘a practical method for grading the cognitive state’ (Folstein et al.). As indicated by the team that designed the MMSE (Folstein et al.), in the Journal of Psychiatric Research, the MMSE "does have a number of valuable features for clinical practice even though it cannot carry alone the diagnostic responsibility.”
· Questions have been raised about the use of the MMSE to track cognitive changes over time, specifically, about the clinical relevance of these changes due to the potential for measurement error.
· One’s score on the MMSE is likely to be negatively skewed by a language barrier. Ironically, some patients in the advanced stages of Alzheimer’s Disease often revert to their native tongue, which, if not the English language, would serve to further skew their score.
· Psychological Medicine published a study back in 1982 that showed an increase in false positives amongst hospital patients with fewer than 9 years of education. Conversely, a highly educated person with mild dementia may score within the normal range on the MMSE.
· Studies have also shown that the test is not accurate in older adults who are illiterate.
· The MMSE is not reliable as a screening tool in someone with a learning disability (see reference) or a physical disability that would impair one’s ability to complete the test (e.g. blindness or deafness).
· A paper published in the Journal of Clinical Epidemiology reviewed MMSE results in older Mexican-Americans and found that the MMSE is ‘strongly influenced’ by noncognitive factors including marital status, language of interview and immigrant status.
When the MMSE is misused or applied inappropriately, cognitive deficits may be missed in some patients, while other patients may be misclassified. However, when applied prudently, and when considered in partnership with additional data (e.g. anecdotal information from family members, or the results of other cognitive tests), the MMSE is both a valuable and valid screening tool for measuring cognitive status.
Jennifer Hartman, Guest Blogger