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NEW ORLEANS -- The Montreal Cognitive Assessment (MoCA) was better than the Mini-Mental State Examination (MMSE) at teasing out subtle differences in cognitive performance among mildly impaired individuals, researchers reported here.

In a study of 555 patients with varying degrees of cognitive impairment participating in the Alzheimer's Disease Neuroimaging Initiative (ADNI), ranging from mild to full-blown dementia, those with MMSE scores near the upper end of its 30-point range showed a much broader spread of MoCA scores, which also uses a 30-point scale, suggesting that the latter may be more useful for detecting changes over relatively short periods of time, according to Helen Hochstetler, PharmD, of Eli Lilly & Co. in Indianapolis, and colleagues.

Among the 422 patients classified as mildly impaired, MMSE scores started at 21, whereas MoCA scores ranged from 13 to 30, according to a poster Hochstetler presented at the American Neurological Association annual meeting. (Citing Lilly company policy, Hochstetler declined to speak on the record with MedPage Today.)

A similar spread of MoCA scores, ranging from 17 to 30, was seen in 283 individuals identified as healthy controls in ADNI, which uses multiple tests to classify participants. Those classifications would be considered more reliable than results from any single test, but may not be practical in many clinical and research settings.

"These data suggest that the MoCA, using a cutoff of ≥17, may be more useful than the MMSE to detect a range of mild cognitive impairment cases," Hochstetler and colleagues concluded in the poster.

The researchers said that, combined with a functional test, the MoCA could be helpful in classifying patients in the borderline area between mild impairment and dementia. Another use for which the MoCA may be better suited than the MMSE is in detecting the earliest stages of impairment.

The problem of reliably detecting small differences in cognitive performance has come to the fore as clinical trials of potential Alzheimer's disease drugs are now focusing on mildly impaired or cognitively normal, high-risk individuals. Lilly has a special stake in this research because its investigational anti-amyloid drug, solanezumab, is being tested in two separate trials in asymptomatic people with large plaque burdens and in patients with early Alzheimer's disease.

The MMSE has been the most commonly used measure of cognitive function in dementia research, but researchers have recognized that it is relatively insensitive and variable in mildly impaired individuals.

MoCA differs from the MMSE mainly by including tests of executive function and abstraction, and by putting less weight on orientation to time and place. Ten of the MMSE's 30 points are scored solely on the time-place orientation test, whereas the MoCA assigns it a maximum of six points.

The MoCA also puts more weight on recall and attention-calculation performance, while de-emphasizing language skill.

Among the three groups in the study, mean MMSE and MoCA scores were as follows:

• Alzheimer's dementia: MMSE 20.89 (SD 4.41); MoCA 16.05 (SD 5.24)
• Mild cognitive impairment: MMSE 27.86 (SD 1.87); MoCA 23.51 (SD 3.28)
• Healthy controls: MMSE 29.10 (SD 1.19); MoCA 25.51 (SD 2.73)

Overall, Hochstetler and colleagues characterized the MoCA as more challenging than the MMSE (hence the lower scores in each category).

The MoCA may have been less useful than the MMSE in patients with overt dementia, Hochstetler and colleagues indicated. Ten of the 122 dementia patients in the study had MoCA scores above the researchers' suggested cutoff of 17, but MMSE scores less than 22. MMSE scores below 22 would generally be interpreted as at least moderate impairment.

Another drawback to the MoCA is that it takes longer than the MMSE to administer, such that it "might not fit into a standard office visit very well," the researchers noted.

Henry Paulson, MD, of the University of Michigan, who was not involved in the study, told MedPage Today that each test has its relative strengths.

"The MMSE is a tried and true measure, quickly administered," he said. "It's good for memory but a little bit deficient on executive dysfunction."

The MoCA "has the same short time frame, a little more in the executive realm -- so it captures one aspect of cognitive dysfunction that exists in many patients," he said.

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