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Prediction of Probable Alzheimer's Disease

Prediction of Probable Alzheimer's disease in memory-impaired patients using the Mini-Mental State Examination, informant and patient ratings

About this study

Earlier research has shown that neuropsychological tests of delayed recall and attention are accurate predictors of incidence Alzheimer's disease in memory-impaired patients1. However, these tests require approximately 20 minutes to administer as well as expertise in their administration and scoring. Therefore, we wanted to determine whether briefer tests, requiring less expertise and time in their administration could be identified. The Mini-Mental State Examination (MMSE)2 is the most commonly used mental status test with the elderly. Unfortunately, studies have shown that the MMSE alone is not particularly accurate in the early identification of AD3. Therefore, we conducted a study examining whether the addition of a brief 19-item interview scale4 completed by someone who is familiar the with patient (an informant) would add to the predictive accuracy of the MMSE. In fact, the addition of this Informant Interview significantly improved the accuracy of the MMSE. Reference to the published findings can be found at:

Tierney, MC, Herrmann, N, Geslani, D & Szalai, JP. Contribution of informant and patient ratings to the accuracy of the Mini-Mental State Examination in predicting probable Alzheimer's disease. Journal of the American Geriatric Society 2003; 51 (6): 813-818.

Our further analyses in this paper indicated that a brief 6-item test could be derived from the items of the MMSE, the Informant Interview scale and Patient Interview scale. This brief 6-item test was significantly more accurate than the combination of the MMSE and the Informant Interview. However, this 6-item test should be used with caution, as replication of these findings with a new sample is required to demonstrate the reliability and validity of this newly derived test.

Using this calculator

When using either the combination of the full MMSE and Informant Interview scale or the brief 6-item test to derive the predicted probability of developing AD for one's patients, a complicated formula must be applied to patients' scores. To simplify this preocedure, this site provides a calculation of this probability once the patient's scores have been entered.

Here is how to proceed:

1. Ensure that it is appropriate that your patient be evaluated with this procedure. Your patient is appropriate if he or she either presents with memory complaints or is brought to you by a family member who has concerns about memory. Furthermore, your judgement (based on the patient's history, physical examination and laboratory work-up for dementia) is that your patient does not meet criteria for a dementing illness.

In addition, your patient must be:

  • 60 years of age or older
  • able to hear normal speech with or without hearing aids
  • able to see normal print with or without visual aids
  • fluent in English and have at least grade 6 education.

2. Print the Informant Interview Scales – or – the brief six-item test.

  • The combination of the MMSE and Informant Interview scales has been shown to be an accurate two-year predictor of Alzheimers. Here is the printable Informant Interview Scale (PDF).
  • The six-item test is shorter, simpler to administer and our initial study shows that it may be more accurate. Here is the printable six-item test (PDF).

3. Administer one or the other to your patient.

4. Enter your patient's scores and calculate their predicted probability of developing AD:

  • The scores for the MMSE and Informant Interview scores are entered here.
  • The scores for the six-item test are entered here.

The percentage score that you will receive when you click on the "Calculate" button represents your patient's probability over the next two years of developing Alzheimer's disease.

Reference list

  1. Tierney MC, Szalai JP, Snow WG, et al. Prediction of probable Alzheimer's disease in memory-impaired patients: a prospective longitudinal study. Neurology 1996;46:661-665.
  2. Folstein M, Folstein S, McHugh S. Mini-Mental State: a practical method for grading the cognitive status of patients for the clinician. J Psychiatr Res 1975;12:189-198.
  3. Tierney MC, Szalai J, Dunn E, Geslani D, McDowell I. Prediction of Probable Alzheimer's disease in patients with symptoms suggestive of memory impairment: value of the Mini-Mental State Examination. Arch Fam Med 2000;9:527-532.
  4. Roth M, Tym E, Mountjoy CQ, et al. CAMDEX. A standardized instrument for the diagnosis of mental disorder in the elderly with special reference to the early detection of dementia. Br J Psychiatry 1986;149:698-709.

The authors of this paper are:

  • Dr. Mary C. Tierney, Senior Scientist and Director of Geriatric Research Unit, Sunnybrook Health Sciences Centre; Professor, Dept. of Family & Community Medicine, University of Toronto
  • Dr. Nathan Herrmann, Dept. of Psychiatry, Sunnybrook Health Sciences Centre; Professor, Dept. of Psychiatry, University of Toronto, Toronto, ON Canada.
  • Ms. Daphne Geslani, Geriatric Research Unit, Sunnybrook Health Sciences Centre
  • Dr. John P. Szalai, Senior Scientist, Clinical Epidemiology & Health Services Research, Sunnybrook Health Sciences Centre; Associate Professor, Dept. of Public Health Sciences, University of Toronto.

Privacy statement

The calculation of predicted probability of Alzheimer disease is a free site for use by physicians and individual web users. No registration or personal information is required. Test data and calculations are not stored on this site's hosting server nor will it be saved or used by us or distributed to outside parties.