A new interpretation of a standard cognitive test may better serve the needs of the more highly educated at risk of dementia.

Summary

The mini-mental state examination is an important part of the diagnosis of dementia, including Alzheimer's disease. In a new study, researchers show that a higher cut off point in the score diagnoses more cases of dementia among the more highly educated than the traditional cut off point. This re-interpretation could help diagnose cases previously missed so that intervention can be started earlier.

Introduction

The mini-mental state examination (MMSE) is a commonly used test of memory, thinking and learning that is a standard part of a workup for cases of suspected dementia. It is also used to monitor progress of the disease and the impact of therapeutic interventions. The maximum score on the MMSE is 30 and a score of 24 or under may indicate dementia, including Alzheimer's disease. Patients with a higher level of education tend to do worse once they are diagnosed with dementia. Their disease progresses faster and they have a higher death rate. Earlier, and more accurate, diagnosis might be particularly helpful to this group. One approach would be to look at whether a different cut off point on the MMSE would be more appropriate for those with more education.

What was done

Sid O'Bryant of Texas Tech University Health Sciences Center and colleagues looked at the MMSE scores of 1,141 individuals in the Mayo Clinic Alzheimer Disease Research Center and Alzheimer Disease Patient Registry who reported having 16 or more years of education. The group included 307 patients with dementia, 176 patients with mild cognitive impairment and 658 patients without dementia who acted as controls.

What was found

Using the traditional cut of point of 24 on the MMSE correctly classified the patient group as having dementia, or not, in 89 % of cases. Raising the cut off point to 27 increased the proportion to 90 %. The change from 24 to 27 decreased the risk of a patient being given either a false positive or a false negative diagnosis.

What this study means

The findings suggest that the traditional MMSE cut off score of 24 does not give optimal diagnostic results for patients who are highly educated and may have dementia. A cut off score of 27 is more likely to pick up all the cases and therefore allow earlier diagnosis in this group. Higher levels of education are thought to provide a cognitive reserve which protects people in the earlier stages of the disease and makes it harder to diagnose. By the time symptoms become apparent, brain damage from dementia may be advanced and the patient has a poor outlook. Earlier diagnosis through a higher cut off of the MMSE test could help identify those with a cognitive reserve who are in the early stages of disease. The researchers suggest that these individuals ought to be referred for further examination as the MMSE is only part of the investigations needed to diagnose dementia.

Source

Detecting dementia with the mini-mental state examination in highly educated individuals SE. O'Bryant, JD. Humphreys,  et al., Archives of Neurology, July 2008, vol. 65, pp. 963--967

Related article

Educated Patients May Need Higher Threshold for Dementia Screening