Which Memory Test Works Best For Early Detection of Alzheimer's Disease?
Head to Head Study Demonstrates AI-Powered MCI Screen is more accurate for early detection of AD
When it comes to Alzheimer’s disease and related disorders (ADRD), catching it early can make all the difference. Primary care settings are often the first line of defense, where routine checkups might reveal the earliest hints of cognitive decline. But not all screening tools are created equal. In a recent study, we put three common tests to the challenge: the Mini-Mental State Exam (MMSE), the Clock Drawing Test (CDT), and the MCI Screen (MCIS). Here’s what we found—and why it matters.
The Study: A Real-World Look at Three Screening Instruments
Study authors examined 254 patients over 65, all visiting primary care and none with a prior ADRD diagnosis. Most—81%—showed no symptoms according to the Functional Assessment Staging Test (FAST), scoring a FAST=1, meaning they seemed perfectly fine day-to-day. Of these, 215 completed all three screening tests: the MMSE (a 30-point questionnaire), the CDT (drawing a clock to test spatial and planning skills), and the MCIS (a detailed cognitive assessment).
The results? Out of the 215, 141 had at least one abnormal test result. Of those, 121 went on for a full diagnostic workup, while 74 (34%) tested normal across the board and didn’t need further evaluation. To keep things fair, the study adjusted for potential bias from those unevaluated cases using statistical methods.
What We Found: Diagnoses and Prevalence
Among those diagnosed, 43% had Alzheimer’s disease, 36% had cerebrovascular disease (think stroke-related issues), and 21% had other causes of cognitive impairment. After adjusting for bias, we estimated that mild cognitive impairment (MCI)—an early warning sign of ADRD—was present in 13.9–20.3% of those with FAST=1 (asymptomatic) and 23.0–28.3% of those with FAST stages 1–3 (ranging from no symptoms to mild issues). That’s a significant chunk of people who might otherwise slip under the radar.
The Tests: A Head-to-Head Comparison
Now, let’s break down how the tests performed:
Clock Drawing Test- Sensitivity: 59% (catches 59% of true cases)
- Specificity: 39% (only 39% accurate at ruling out non-cases)
- Overall accuracy: 54%
- Validity (kappa statistic): -0.02 (p=0.61)—essentially no better than a coin flip
- Positive predictive value: 16% (if it flags you, there’s only a 16% chance it’s right)
- Negative predictive value: 83% (if it clears you, it’s usually correct)
- Sensitivity: 71%
- Specificity: 36%
- Overall accuracy: 62%
- Validity (kappa statistic): 0.06 (p=0.23)—still not statistically significant
- Positive predictive value: 17%
- Sensitivity: 94%
- Specificity: 97%
- Overall accuracy: 96%
- Validity (kappa statistic): 0.92 (p<0.0001)—highly significant
- Positive predictive value: 86%
- Negative predictive value: 87%
The CDT and MMSE struggled to reliably spot early ADRD. The CDT’s validity was practically nonexistent, and the MMSE didn’t fare much better—both had low specificity and low positive predictive values, meaning they flagged too many false positives. The MCIS, on the other hand, performed well with near-perfect sensitivity, specificity, and accuracy. It caught nearly all true cases and rarely misidentified healthy patients.
Why This Matters for You
If you’re over 65—or have a loved one who is—screening for cognitive decline in primary care could be a game-changer. But the tool your doctor uses matters. The MMSE and CDT, while widely used, just don’t cut it for early detection. They’re not precise enough to catch subtle changes, especially in people who still seem fine on the surface. The MCIS, however, offers a much clearer picture, giving doctors a reliable way to identify who needs a closer look and who’s in the clear.
Early detection isn’t just about a diagnosis—it’s about planning, managing, and potentially slowing the progression of ADRD. With Alzheimer’s affecting nearly half of diagnosed cases in our study, and other conditions like cerebrovascular disease also common, the stakes are high. A tool like the MCIS could help primary care step up its game, catching these conditions before they fully take hold.
The Bottom Line
This study shows that for early detection of Alzheimer’s and related disorders, the MCI Screen outperforms the Mini-Mental State Exam and Clock Drawing Test by a wide margin. If you’re a patient, caregiver, or provider, it’s worth asking: is the right tool being used? Because when it comes to brain health, precision matters—and the earlier we act, the better.
1. Trenkle DL, Shankle WR, Azen SP. Detecting Cognitive Impairment in Primary Care: Performance Assessment of Three Screening Instruments. Journal of Alzheimer’s Disease. 2007;11(3):323-335. doi:10.3233/JAD-2007-11309
