MMSE: Where Does It Fit?

The MMSE is probably the most widely used standardized cognitive screening test. (Assessment Scales text) It was first described by Folstein in 1975 as a "practical method for grading the cognitive state".¹ Folstein had suggested a cutoff score of 23/30 or less, for the presence of dementia in persons with at least 8 years of education. It was called "mini" because it did not test mood or thought disorders. It was intended to assist psychiatric residents in the cognitive part of the mental status exam but was never meant to be used for diagnosis of dementia.

Never the less the MMSE has been used extensively in the field of dementia.² In 1989 O'Connnor et al. found a sensitivity of 86% and a specificity of 92% when a cutoff of 23-24/30 was used.³ There have been many standardizations and papers written about its use in clinical trials as well the suggestion that it become part of every family practitioners routine assessment of the elderly. In practicality it is used by some family doctors who have time and inclination to use it, as well as most anyone looking after patients with memory problems including nurses, doctors, psychologists, physicians and occupational therapists to name a few.

The benefits of the MMSE include its brevity (5-10 minutes to administer), and the fact that it is a global assessment of many domains including: orientation to time and place (10 points), registration of 3 words (3 points), attention and calculation (5 points), recall of 3 words (3 points), language (8 points) and visual construction (1 point).

The standardized MMSE has been used to look at disease progression as well as rating it to areas of functional impairment.

Some of the least useful areas of the MMSE include the naming (because the words are commonly used and such high frequency words are usually named properly), the 3 step command (because this is usually done correctly in early and moderate dementia), and the phrase repetition (also well preserved in early dementia and dependent on hearing and to some extent on culture). Reading the sentence "Close your eyes" is also a task that is well preserved in early dementia. It is reading comprehension that is disproportionately impaired in early Alzheimer's.

Limitations of the MMSE include the floor effect i.e. it is less useful in the low range, which is the score you find in advanced dementia, in those with little formal education and those with severe language problems as part of their dementia (aphasia).⁴ There is also a ceiling effect i.e. in those who are very well educated you may get a score of 30/30 even though you feel clinically that the patient meets the criteria for dementia.⁵ In well-educated patients with Alzheimer's Disease some studies have found a 2-5 point drop per year in the MMSE whereas others have shown as little as 0.3 point change per year showing the great degree of heterogeneity in the disease as well as the limitations of a single psychometric test.⁶

A recent meta-analysis of 37 longitudinal studies where the MMSE was used to follow patients with Alzheimer Disease over a 10 year period found an average ARC (annual rate of change score) of 3.3 MMSE points.⁷

In summary, the MMSE is a useful screening test for cognitive impairment. It takes 5-10 minutes to administer and is reliable. Scores range from 25-30 for normals, 21-24 for mild AD, 14-20 for moderate AD, and less than 13 in severe AD. It is a useful tool in the initial assessment as well as the ongoing follow-up of patients with AD.

The MMSE is not a diagnostic test nor is it equivalent to a neurological examination or formal mental status testing. It is not a test of personality, mood, behavior or function and does not by itself determine competence. It is not always sensitive in picking up early dementia and does depend on educational background. It is less helpful is forms of dementia where there are early and severe language problems.

The MMSE is a useful test for family physicians. Once the limitations of the test are understood, it can be very helpful in both the diagnosis of dementia and in monitoring the response to the new agents being used to treat Alzheimer's Disease.

- Mary Gorman MD, CCFP

Thanks to Dr. Ken Rockwood, specialist in Geriatrics and Associate Professor of Medicine at Dalhousie University School of Medicine, Halifax, Nova Scotia, for reviewing the draft copy of this article.

References:

1. Folstein MF, Folstein SE, McHugh PR (1975) "Mini-Mental /state": a practical method for grading the cognitive state of patients for the clinician. Journal of Psychiatric Research 12: 189-98
    
2. McDowell I, Kristjansson B, Hill GB, Hebert R. Communtiy screening for dementia: the Mini-Mental State Exam (MMSE) and Modified Mini-Mental State Exam (3MS) compared. J clin Epidemiol. 1977 Apr;50(4):377-83.
    
3. O'Connor DW, Pollitt P, Hyde JB et al. The reliability and validity of the Mini-Mental State in a British community survey. J Psychiat Res 1989: 23: 87-96.
    
4. Vertese A, Lever JA, Molloy D et al. Standardized Mini-Mental State Examination; use and interpretation. Can Fam Physician. 2001;472018-2023.
    
5. Simard M. The Mini-Mental State Examination: Strengths and Weaknesses of a Clinical Instrument. The Canadian Alzheimer Disease Review. 1998 Dec 12.
    
6. Reisberg B, Burns A, Brodaty H et al. Diagnosis of Alzheimer's Disease, Report of an International Psychogeriatric Association Meeting Work Group. Int psychoger.1997. 9;supp 1:11-38.
    
7. Han L, Cole M, Bellavance F et al. Tracking Cognitive Decline in Alzheimer's Disease Using the Mini-Mental State Examination: A Meta-analysis. International Psychogeriatrics. 2000 12;(2):231-247.
    

You can search for abstracts of the above references by following this link: PubMed